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Sample records for 2-keto-3-deoxy-d-glycero-d-galactonononate-9-phosphate phosphatase defines

  1. Structure-Function Analysis of 2-Keto-3-Deoxy-D-Glycero-D-Galacto-Nononate-9-Phosphate Phosphatase Defines Specificity Elements in Type C0 had Family Members

    SciTech Connect

    Lu, Z.; Wang, L; Dunaway-Mariano, D; Allen, K

    2009-01-01

    The phosphotransferases of the haloalkanoate dehalogenase superfamily (HADSF) act upon a wide range of metabolites in all eukaryotes and prokaryotes and thus constitute a significant force in cell function. The challenge posed for biochemical function assignment of HADSF members is the identification of the structural determinants that target a specific metabolite. The '8KDOP' subfamily of the HADSF is defined by the known structure and catalytic activity of 2-keto-3-deoxy-8-phospho-d-manno-octulosonic acid (KDO-8-P) phosphatase. Homologues of this enzyme have been uniformly annotated as KDO-8-P phosphatase. One such gene, BT1713, from the Bacteroides thetaiotaomicron genome was recently found to encode the enzyme 2-keto-3-deoxy-d-glycero-d-galacto-9-phosphonononic acid (KDN-9-P) phosphatase in the biosynthetic pathway of the 9-carbon ?-keto acid, 2-keto-3-deoxy-d-glycero-d-galactonononic acid (KDN). To find the structural elements that provide substrate-specific interactions and to allow identification of genomic sequence markers, the x-ray crystal structures of BT1713 liganded to the cofactor Mg2+and complexed with tungstate or Formula/Neu5Ac were determined to 1.1, 1.85, and 1.63 A resolution, respectively. The structures define the active site to be at the subunit interface and, as confirmed by steady-state kinetics and site-directed mutagenesis, reveal Arg-64*, Lys-67*, and Glu-56 to be the key residues involved in sugar binding that are essential for BT1713 catalytic function. Bioinformatic analyses of the differentially conserved residues between BT1713 and KDO-8-P phosphatase homologues guided by the knowledge of the structure-based specificity determinants define Glu-56 and Lys-67* to be the key residues that can be used in future annotations.

  2. The variable subunit associated with protein phosphatase 2A0 defines a novel multimember family of regulatory subunits.

    PubMed Central

    Zolnierowicz, S; Van Hoof, C; Andjelković, N; Cron, P; Stevens, I; Merlevede, W; Goris, J; Hemmings, B A

    1996-01-01

    Two protein phosphatase 2A (PP2A) holoenzymes were isolated from rabbit skeletal muscle containing, in addition to the catalytic and PR65 regulatory subunits, proteins of apparent molecular masses of 61 and 56 kDa respectively. Both holoenzymes displayed low basal phosphorylase phosphatase activity, which could be stimulated by protamine to an extent similar to that of previously characterized PP2A holoenzymes. Protein micro-sequencing of tryptic peptides derived from the 61 kDa protein, termed PR61, yielded 117 residues of amino acid sequence. Molecular cloning by enrichment of specific mRNAs, followed by reverse transcription-PCR and cDNA library screening, revealed that this protein exists in multiple isoforms encoded by at least three genes, one of which gives rise to several splicing variants. Comparisons of these sequences with the available databases identified one more human gene and predicted another based on a rabbit cDNA-derived sequence, thus bringing the number of genes encoding PR61 family members to five. Peptide sequences derived from PR61 corresponded to the deduced amino acid sequences of either alpha or beta isoforms, indicating that the purified PP2A preparation was a mixture of at least two trimers. In contrast, the 56 kDa subunit (termed PR56) seems to correspond to the epsilon isoform of PR61. Several regulatory subunits of PP2A belonging to the PR61 family contain consensus sequences for nuclear localization and might therefore target PP2A to nuclear substrates. PMID:8694763

  3. Human monoclonal antibodies isolated from type I diabetes patients define multiple epitopes in the protein tyrosine phosphatase-like IA-2 antigen.

    PubMed

    Kolm-Litty, V; Berlo, S; Bonifacio, E; Bearzatto, M; Engel, A M; Christie, M; Ziegler, A G; Wild, T; Endl, J

    2000-10-15

    Protein tyrosine phosphatase-like IA-2 autoantigen is one of the major targets of humoral autoimmunity in patients with insulin-dependant diabetes mellitus (IDDM). In an effort to define the epitopes recognized by autoantibodies against IA-2, we generated five human mAbs (hAbs) from peripheral B lymphocytes isolated from patients most of whom had been recently diagnosed for IDDM. Determination and fine mapping of the critical regions for autoantibody binding was performed by RIA using mutant and chimeric constructs of IA-2- and IA-2beta-regions. Four of the five IgG autoantibodies recognized distinct epitopes within the protein tyrosine phosphatase (PTP)-like domain of IA-2. The minimal region required for binding by three of the PTP-like domain-specific hAbs could be located to aa 777-979. Two of these hAbs cross-reacted with the related IA-2beta PTP-like domain (IA-2beta aa 741-1033). A further PTP-like domain specific hAb required the entire PTP-like domain (aa 687-979) for binding, but critical amino acids clustered in the N-terminal region 687-777. An additional epitope could be localized within the juxtamembrane domain (aa 603-779). In competition experiments, the epitope recognized by one of the hAbs was shown to be targeted by 10 of 14 anti-IA-2-positive sera. Nucleotide sequence analysis of this hAb revealed that it used a V(H) germline gene (DP-71) preferably expressed in autoantibodies associated with IDDM. The presence of somatic mutations in both heavy and light chain genes and the high affinity or this Ab suggest that the immune response to IA-2 is Ag driven. PMID:11035111

  4. ALP (Alkaline Phosphatase) Test

    MedlinePlus

    ... known as: ALK PHOS; Alkp Formal name: Alkaline Phosphatase Related tests: AST ; ALT ; GGT ; Bilirubin ; Liver Panel ; Bone Markers ; Alkaline Phosphatase Isoenzymes; Bone Specific ALP All content on Lab ...

  5. Protein phosphatases and their regulation in the control of mitosis

    PubMed Central

    Mochida, Satoru; Hunt, Tim

    2012-01-01

    Cell cycle transitions depend on protein phosphorylation and dephosphorylation. The discovery of cyclin-dependent kinases (CDKs) and their mode of activation by their cyclin partners explained many important aspects of cell cycle control. As the cell cycle is basically a series of recurrences of a defined set of events, protein phosphatases must obviously be as important as kinases. However, our knowledge about phosphatases lags well behind that of kinases. We still do not know which phosphatase(s) is/are truly responsible for dephosphorylating CDK substrates, and we know very little about whether and how protein phosphatases are regulated. Here, we summarize our present understanding of the phosphatases that are important in the control of the cell cycle and pose the questions that need to be answered as regards the regulation of protein phosphatases. PMID:22482124

  6. Structural mechanisms of plant glucan phosphatases in starch metabolism.

    PubMed

    Meekins, David A; Vander Kooi, Craig W; Gentry, Matthew S

    2016-07-01

    Glucan phosphatases are a recently discovered class of enzymes that dephosphorylate starch and glycogen, thereby regulating energy metabolism. Plant genomes encode two glucan phosphatases, called Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), that regulate starch metabolism by selectively dephosphorylating glucose moieties within starch glucan chains. Recently, the structures of both SEX4 and LSF2 were determined, with and without phosphoglucan products bound, revealing the mechanism for their unique activities. This review explores the structural and enzymatic features of the plant glucan phosphatases, and outlines how they are uniquely adapted to perform their cellular functions. We outline the physical mechanisms used by SEX4 and LSF2 to interact with starch glucans: SEX4 binds glucan chains via a continuous glucan-binding platform comprising its dual-specificity phosphatase domain and carbohydrate-binding module, while LSF2 utilizes surface binding sites. SEX4 and LSF2 both contain a unique network of aromatic residues in their catalytic dual-specificity phosphatase domains that serve as glucan engagement platforms and are unique to the glucan phosphatases. We also discuss the phosphoglucan substrate specificities inherent to SEX4 and LSF2, and outline structural features within the active site that govern glucan orientation. This review defines the structural mechanism of the plant glucan phosphatases with respect to phosphatases, starch metabolism and protein-glucan interaction, thereby providing a framework for their application in both agricultural and industrial settings. PMID:26934589

  7. Alkaline Phosphatase in Stem Cells

    PubMed Central

    Štefková, Kateřina; Procházková, Jiřina; Pacherník, Jiří

    2015-01-01

    Alkaline phosphatase is an enzyme commonly expressed in almost all living organisms. In humans and other mammals, determinations of the expression and activity of alkaline phosphatase have frequently been used for cell determination in developmental studies and/or within clinical trials. Alkaline phosphatase also seems to be one of the key markers in the identification of pluripotent embryonic stem as well as related cells. However, alkaline phosphatases exist in some isoenzymes and isoforms, which have tissue specific expressions and functions. Here, the role of alkaline phosphatase as a stem cell marker is discussed in detail. First, we briefly summarize contemporary knowledge of mammalian alkaline phosphatases in general. Second, we focus on the known facts of its role in and potential significance for the identification of stem cells. PMID:25767512

  8. Modulators of intestinal alkaline phosphatase.

    PubMed

    Bobkova, Ekaterina V; Kiffer-Moreira, Tina; Sergienko, Eduard A

    2013-01-01

    Small molecule modulators of phosphatases can lead to clinically useful drugs and serve as invaluable tools to study functional roles of various phosphatases in vivo. Here, we describe lead discovery strategies for identification of inhibitors and activators of intestinal alkaline phosphatases. To identify isozyme-selective inhibitors and activators of the human and mouse intestinal alkaline phosphatases, ultrahigh throughput chemiluminescent assays, utilizing CDP-Star as a substrate, were developed for murine intestinal alkaline phosphatase (mIAP), human intestinal alkaline phosphatase (hIAP), human placental alkaline phosphatase (PLAP), and human tissue-nonspecific alkaline phosphatase (TNAP) isozymes. Using these 1,536-well assays, concurrent HTS screens of the MLSMR library of 323,000 compounds were conducted for human and mouse IAP isozymes monitoring both inhibition and activation. This parallel screening approach led to identification of a novel inhibitory scaffold selective for murine intestinal alkaline phosphatase. SAR efforts based on parallel testing of analogs against different AP isozymes generated a potent inhibitor of the murine IAP with IC50 of 540 nM, at least 65-fold selectivity against human TNAP, and >185 selectivity against human PLAP. PMID:23860652

  9. Structural Genomics of Protein Phosphatases

    SciTech Connect

    Almo,S.; Bonanno, J.; Sauder, J.; Emtage, S.; Dilorenzo, T.; Malashkevich, V.; Wasserman, S.; Swaminathan, S.; Eswaramoorthy, S.; et al

    2007-01-01

    The New York SGX Research Center for Structural Genomics (NYSGXRC) of the NIGMS Protein Structure Initiative (PSI) has applied its high-throughput X-ray crystallographic structure determination platform to systematic studies of all human protein phosphatases and protein phosphatases from biomedically-relevant pathogens. To date, the NYSGXRC has determined structures of 21 distinct protein phosphatases: 14 from human, 2 from mouse, 2 from the pathogen Toxoplasma gondii, 1 from Trypanosoma brucei, the parasite responsible for African sleeping sickness, and 2 from the principal mosquito vector of malaria in Africa, Anopheles gambiae. These structures provide insights into both normal and pathophysiologic processes, including transcriptional regulation, regulation of major signaling pathways, neural development, and type 1 diabetes. In conjunction with the contributions of other international structural genomics consortia, these efforts promise to provide an unprecedented database and materials repository for structure-guided experimental and computational discovery of inhibitors for all classes of protein phosphatases.

  10. Glucose-6-phosphatase deficiency

    PubMed Central

    2011-01-01

    Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea). Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty), generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma) and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency). GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia) which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib). Mutations in the genes G6PC (17q21) and SLC37A4 (11q23) respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most commonly confirmed

  11. Cellular phosphatases facilitate combinatorial processing of receptor-activated signals

    PubMed Central

    Kumar, Dhiraj; Dua, Raina; Srikanth, Ravichandran; Jayaswal, Shilpi; Siddiqui, Zaved; Rao, Kanury VS

    2008-01-01

    Background Although reciprocal regulation of protein phosphorylation represents a key aspect of signal transduction, a larger perspective on how these various interactions integrate to contribute towards signal processing is presently unclear. For example, a key unanswered question is that of how phosphatase-mediated regulation of phosphorylation at the individual nodes of the signaling network translates into modulation of the net signal output and, thereby, the cellular phenotypic response. Results To address the above question we, in the present study, examined the dynamics of signaling from the B cell antigen receptor (BCR) under conditions where individual cellular phosphatases were selectively depleted by siRNA. Results from such experiments revealed a highly enmeshed structure for the signaling network where each signaling node was linked to multiple phosphatases on the one hand, and each phosphatase to several nodes on the other. This resulted in a configuration where individual signaling intermediates could be influenced by a spectrum of regulatory phosphatases, but with the composition of the spectrum differing from one intermediate to another. Consequently, each node differentially experienced perturbations in phosphatase activity, yielding a unique fingerprint of nodal signals characteristic to that perturbation. This heterogeneity in nodal experiences, to a given perturbation, led to combinatorial manipulation of the corresponding signaling axes for the downstream transcription factors. Conclusion Our cumulative results reveal that it is the tight integration of phosphatases into the signaling network that provides the plasticity by which perturbation-specific information can be transmitted in the form of a multivariate output to the downstream transcription factor network. This output in turn specifies a context-defined response, when translated into the resulting gene expression profile. PMID:18798986

  12. Phosphotyrosine Substrate Sequence Motifs for Dual Specificity Phosphatases

    PubMed Central

    Zhao, Bryan M.; Keasey, Sarah L.; Tropea, Joseph E.; Lountos, George T.; Dyas, Beverly K.; Cherry, Scott; Raran-Kurussi, Sreejith; Waugh, David S.; Ulrich, Robert G.

    2015-01-01

    Protein tyrosine phosphatases dephosphorylate tyrosine residues of proteins, whereas, dual specificity phosphatases (DUSPs) are a subgroup of protein tyrosine phosphatases that dephosphorylate not only Tyr(P) residue, but also the Ser(P) and Thr(P) residues of proteins. The DUSPs are linked to the regulation of many cellular functions and signaling pathways. Though many cellular targets of DUSPs are known, the relationship between catalytic activity and substrate specificity is poorly defined. We investigated the interactions of peptide substrates with select DUSPs of four types: MAP kinases (DUSP1 and DUSP7), atypical (DUSP3, DUSP14, DUSP22 and DUSP27), viral (variola VH1), and Cdc25 (A-C). Phosphatase recognition sites were experimentally determined by measuring dephosphorylation of 6,218 microarrayed Tyr(P) peptides representing confirmed and theoretical phosphorylation motifs from the cellular proteome. A broad continuum of dephosphorylation was observed across the microarrayed peptide substrates for all phosphatases, suggesting a complex relationship between substrate sequence recognition and optimal activity. Further analysis of peptide dephosphorylation by hierarchical clustering indicated that DUSPs could be organized by substrate sequence motifs, and peptide-specificities by phylogenetic relationships among the catalytic domains. The most highly dephosphorylated peptides represented proteins from 29 cell-signaling pathways, greatly expanding the list of potential targets of DUSPs. These newly identified DUSP substrates will be important for examining structure-activity relationships with physiologically relevant targets. PMID:26302245

  13. Phosphatase regulation of macrophage activation.

    PubMed

    Kozicky, Lisa K; Sly, Laura M

    2015-08-01

    Macrophages are innate immune cells that play critical roles in tissue homeostasis and the immune response to invading pathogens or tumor cells. A hallmark of macrophages is their "plasticity," that is, their ability to respond to cues in their local microenvironment and adapt their activation state or phenotype to mount an appropriate response. During the inflammatory response, macrophages may be required to mount a profound anti-bacterial or anti-tumor response, an anti-inflammatory response, an anti-parasitic response, or a wound healing response. To do so, macrophages express cell surface receptors for growth factors, chemokines and cytokines, as well pathogen and danger associated molecular patterns. Downstream of these cell surface receptors, cell signalling cascades are activated and deactivated by reversible and competing activities of lipid and protein kinases and phosphatases. While kinases drive the activation of cell signalling pathways critical for macrophage activation, the strength and duration of the signalling is regulated by phosphatases. Hence, gene knockout mouse models have revealed critical roles for lipid and protein phosphatases in macrophage activation. Herein, we describe our current understanding and the key roles of specific cellular phosphatases in the regulation of the quality of macrophage polarization as well as the quantity of cytokines produced by activated macrophages. PMID:26216598

  14. Determination of liver microsomal glucose-6-phosphatase.

    PubMed

    Zak, B; Epstein, E; Baginski, E S

    1977-01-01

    A procedure for the determination of liver microsomal glucose-6-phosphatase is described. Homogenization and ultracentrifrigation were used to prepare a precipitate whose character was defined by monitoring the desire enzyme activity which serves as a marker. Activity of the enzyme was determined by means of a sensitive colorimetric reaction for the product, inorganic phosphate. Non-enzymatic hydrolysis problems with the substrate are minimized in this procedure by the masking action of citrate. The final heteropoly blue color appears to be considerably sensitized by interaction of phosphomolybdous ion with arsenite. The stability of the relatively labile enzyme was ensured by chelating any metals present with ethylene diamine tetraacetic acid. The overall results obtained by the procedure appear to be useful as an aid in the diagnosis of Type I glycogenosis, a glycogen storage disease called Von Gierke's disease. PMID:192125

  15. The glucose-6-phosphatase system.

    PubMed Central

    van Schaftingen, Emile; Gerin, Isabelle

    2002-01-01

    Glucose-6-phosphatase (G6Pase), an enzyme found mainly in the liver and the kidneys, plays the important role of providing glucose during starvation. Unlike most phosphatases acting on water-soluble compounds, it is a membrane-bound enzyme, being associated with the endoplasmic reticulum. In 1975, W. Arion and co-workers proposed a model according to which G6Pase was thought to be a rather unspecific phosphatase, with its catalytic site oriented towards the lumen of the endoplasmic reticulum [Arion, Wallin, Lange and Ballas (1975) Mol. Cell. Biochem. 6, 75--83]. Substrate would be provided to this enzyme by a translocase that is specific for glucose 6-phosphate, thereby accounting for the specificity of the phosphatase for glucose 6-phosphate in intact microsomes. Distinct transporters would allow inorganic phosphate and glucose to leave the vesicles. At variance with this substrate-transport model, other models propose that conformational changes play an important role in the properties of G6Pase. The last 10 years have witnessed important progress in our knowledge of the glucose 6-phosphate hydrolysis system. The genes encoding G6Pase and the glucose 6-phosphate translocase have been cloned and shown to be mutated in glycogen storage disease type Ia and type Ib respectively. The gene encoding a G6Pase-related protein, expressed specifically in pancreatic islets, has also been cloned. Specific potent inhibitors of G6Pase and of the glucose 6-phosphate translocase have been synthesized or isolated from micro-organisms. These as well as other findings support the model initially proposed by Arion. Much progress has also been made with regard to the regulation of the expression of G6Pase by insulin, glucocorticoids, cAMP and glucose. PMID:11879177

  16. Myosin light-chain phosphatase.

    PubMed Central

    Morgan, M; Perry, S V; Ottaway, J

    1976-01-01

    1. A method for the isolation of a new enzyme, myosin light-chain phosphatase, from rabbit white skeletal muscle by using a Sepharose-phosphorylated myosin light-chain affinity column is described. 2. The enzyme migrated as a single component on electrophoresis in sodium dodecyl sulphate/polyacrylamide gel at pH7.0, with apparent mol.wt. 70000. 3. The enzyme was highly specific for the phosphorylated P-light chain of myosin, had pH optima at 6.5 and 8.0 and was not inhibited by NaF. 4. A Ca2+-sensitive 'ATPase' (adenosine triphosphatase) system consisting of myosin light-chain kinase, myosin light-chain phosphatase and the P-light chain is described. 5. Evidence is presented for a phosphoryl exchange between Pi, phosphorylated P-light chain and myosin light-chain phosphatase. 6. Heavy meromyosin prepared by chymotryptic digestion can be phosphorylated by myosin light-chain kinase. 7. The ATPase activities of myosin and heavy meromyosin, in the presence and absence of F-actin, were not significantly changed (+/- 10%) by phosphorylation of the P-light chain. Images PLATE 1 PMID:186030

  17. Defining "Development".

    PubMed

    Pradeu, Thomas; Laplane, Lucie; Prévot, Karine; Hoquet, Thierry; Reynaud, Valentine; Fusco, Giuseppe; Minelli, Alessandro; Orgogozo, Virginie; Vervoort, Michel

    2016-01-01

    Is it possible, and in the first place is it even desirable, to define what "development" means and to determine the scope of the field called "developmental biology"? Though these questions appeared crucial for the founders of "developmental biology" in the 1950s, there seems to be no consensus today about the need to address them. Here, in a combined biological, philosophical, and historical approach, we ask whether it is possible and useful to define biological development, and, if such a definition is indeed possible and useful, which definition(s) can be considered as the most satisfactory. PMID:26969977

  18. Defining Infertility

    MedlinePlus

    ... of the American Society for Reproductive Medicine Defining infertility What is infertility? Infertility is “the inability to conceive after 12 months ... to conceive after 6 months is generally considered infertility. How common is it? Infertility affects 10%-15% ...

  19. Defining Risk.

    ERIC Educational Resources Information Center

    Tholkes, Ben F.

    1998-01-01

    Defines camping risks and lists types and examples: (1) objective risk beyond control; (2) calculated risk based on personal choice; (3) perceived risk; and (4) reckless risk. Describes campers to watch ("immortals" and abdicators), and several "treatments" of risk: avoidance, safety procedures and well-trained staff, adequate insurance, and a…

  20. Defining cure.

    PubMed

    Hilton, Paul; Robinson, Dudley

    2011-06-01

    This paper is a summary of the presentations made as Proposal 2-"Defining cure" to the 2nd Annual meeting of the ICI-Research Society, in Bristol, 16th June 2010. It reviews definitions of 'cure' and 'outcome', and considers the impact that varying definition may have on prevalence studies and cure rates. The difference between subjective and objective outcomes is considered, and the significance that these different outcomes may have for different stakeholders (e.g. clinicians, patients, carers, industry etc.) is discussed. The development of patient reported outcome measures and patient defined goals is reviewed, and consideration given to the use of composite end-points. A series of proposals are made by authors and discussants as to how currently validated outcomes should be applied, and where our future research activity in this area might be directed. PMID:21661023

  1. [Phosphoprotein phosphatase nonspecifically hydrolyzes CoA].

    PubMed

    Reziapkin, V I; Moiseenok, A G

    1988-01-01

    CoA hydrolysis was studied by a homogenous phosphoprotein phosphatase (EC 3.1 3.16) preparation from bovine spleen nuclei at pH 5.8. Phosphoprotein phosphatase catalyzed hydrolysis of the CoA 3'-phosphoester bond to form dephospho-CoA and Pi. The Km value for phosphoprotein phosphatase with CoA as substrate was 3.7 mM, the specific activity - 0.26 mmol Pi.min-1.mg-1. Phosphoprotein phosphatase did not essentially catalyze the calcium pantothenate hydrolysis (not more than 2% as compared with the CoA hydrolysis rate). PMID:2849829

  2. Protein phosphatases in pancreatic islets

    PubMed Central

    Ortsäter, Henrik; Grankvist, Nina; Honkanen, Richard E.; Sjöholm1, Åke

    2014-01-01

    The prevalence of diabetes is increasing rapidly world-wide. A cardinal feature of most forms of diabetes is the lack of insulin-producing capability, due to the loss of insulin-producing β-cells, impaired glucose-sensitive insulin secretion from the β-cell, or a combination thereof, the reasons for which largely remain elusive. Reversible phosphorylation is an important and versatile mechanism for regulating the biological activity of many intracellular proteins, which, in turn, controls a variety of cellular functions. For instance, significant changes in protein kinase activities and in protein phosphorylation patterns occur subsequent to stimulation of insulin release by glucose. Therefore, the molecular mechanisms regulating phosphorylation of proteins involved in the insulin secretory process by the β-cell have been extensively investigated. However, far less is known about the role and regulation of protein dephosphorylation by various protein phosphatases. Herein we review extant data implicating serine/threonine and tyrosine phosphatases in various aspects of healthy and diabetic islet biology, ranging from control of hormonal stimulus-secretion coupling to mitogenesis and apoptosis. PMID:24681827

  3. Defining chaos

    SciTech Connect

    Hunt, Brian R.; Ott, Edward

    2015-09-15

    In this paper, we propose, discuss, and illustrate a computationally feasible definition of chaos which can be applied very generally to situations that are commonly encountered, including attractors, repellers, and non-periodically forced systems. This definition is based on an entropy-like quantity, which we call “expansion entropy,” and we define chaos as occurring when this quantity is positive. We relate and compare expansion entropy to the well-known concept of topological entropy to which it is equivalent under appropriate conditions. We also present example illustrations, discuss computational implementations, and point out issues arising from attempts at giving definitions of chaos that are not entropy-based.

  4. Inositol lipid phosphatases in membrane trafficking and human disease.

    PubMed

    Billcliff, Peter G; Lowe, Martin

    2014-07-15

    The specific interaction of phosphoinositides with proteins is critical for a plethora of cellular processes, including cytoskeleton remodelling, mitogenic signalling, ion channel regulation and membrane traffic. The spatiotemporal restriction of different phosphoinositide species helps to define compartments within the cell, and this is particularly important for membrane trafficking within both the secretory and endocytic pathways. Phosphoinositide homoeostasis is tightly regulated by a large number of inositol kinases and phosphatases, which respectively phosphorylate and dephosphorylate distinct phosphoinositide species. Many of these enzymes have been implicated in regulating membrane trafficking and, accordingly, their dysregulation has been linked to a number of human diseases. In the present review, we focus on the inositol phosphatases, concentrating on their roles in membrane trafficking and the human diseases with which they have been associated. PMID:24966051

  5. A critical evaluation of a specific radioimmunoassay for prostatic acid phosphatase

    SciTech Connect

    Goldenberg, S.L.; Silver, H.K.; Sullivan, L.D.; Morse, M.J.; Archibald, E.L.

    1982-11-01

    A radioimmunoassay (RIA) method for acid phosphatase detection was compared to a standard enzyme assay using sera from 210 normal volunteers and 285 patients with prostatic disease. Statistical and clinical comparisons were made between defined subgroups. All 55 normal females had RIA detectable serum acid phosphatase, implying that this assay cannot be entirely specific for enzyme of prostatic origin. Urinary catheterization did not affect acid phosphatase levels. In all stages of carcinoma there were more acid phosphatase elevations by the RIA method than enzyme method, but neither assay could differentiate intercapsular cancer from benign prostatic hyperplasia. A small number of patients with biopsy proven negative nodules had marginally elevated values, suggesting an obligation for closer follow-up. The RIA method may be superior for monitoring patients with more advanced malignancy. Additional practical advantages of the RIA include relative simplicity and elimination of the special serum handling required for the enzyme assay.

  6. HuPho: the human phosphatase portal.

    PubMed

    Liberti, Susanna; Sacco, Francesca; Calderone, Alberto; Perfetto, Livia; Iannuccelli, Marta; Panni, Simona; Santonico, Elena; Palma, Anita; Nardozza, Aurelio P; Castagnoli, Luisa; Cesareni, Gianni

    2013-01-01

    Phosphatases and kinases contribute to the regulation of protein phosphorylation homeostasis in the cell. Phosphorylation is a key post-translational modification underlying the regulation of many cellular processes. Thus, a comprehensive picture of phosphatase function and the identification of their target substrates would aid a systematic approach to a mechanistic description of cell signalling. Here we present a website designed to facilitate the retrieval of information about human protein phosphatases. To this end we developed a search engine to recover and integrate information annotated in several publicly available web resources. In addition we present a text-mining-assisted annotation effort aimed at extracting phosphatase related data reported in the scientific literature. The HuPho (human phosphatases) website can be accessed at http://hupho.uniroma2.it. PMID:22804825

  7. Phosphoinositide Phosphatases in Cell Biology and Disease

    PubMed Central

    Liu, Yang; Bankaitis, Vytas A.

    2010-01-01

    Phosphoinositides are essential signaling molecules linked to a diverse array of cellular processes in eukaryotic cells. The metabolic interconversions of these phospholipids are subject to exquisite spatial and temporal regulation executed by arrays of phosphatidylinositol (PtdIns) and phosphoinositide-metabolizing enzymes. These include PtdIns- and phosphoinositide-kinases that drive phosphoinositide synthesis, and phospholipases and phosphatases that regulate phosphoinositide degradation. In the past decade, phosphoinositide phosphatases have emerged as topics of particular interest. This interest is driven by the recent appreciation that these enzymes represent primary mechanisms for phosphoinositide degradation, and because of their ever-increasing connections with human diseases. Herein, we review the biochemical properties of six major phosphoinositide phosphatases, the functional involvements of these enzymes in regulating phosphoinositide metabolism, the pathologies that arise from functional derangements of individual phosphatases, and recent ideas concerning the involvements of phosphoinositide phosphatases in membrane traffic control. PMID:20043944

  8. Specificity of a protein phosphatase inhibitor from rabbit skeletal muscle.

    PubMed Central

    Cohen, P; Nimmo, G A; Antoniw, J F

    1977-01-01

    A hear-stable protein, which is a specific inhibitor of protein phosphatase-III, was purified 700-fold from skeletal muscle by a procedure that involved heat-treatment at 95 degrees C, chromatography on DEAE-cellulose and gel filtration on Sephadex G-100. The final step completely resolved the protein phosphatase inhibitor from the protein inhibitor of cyclic AMP-dependent protein kinase. The phosphorylase phosphatase, beta-phosphorylase kinase phosphatase, glycogen synthase phosphatase-1 and glycogen synthase phosphatase-2 activities of protein phosphatase-III [Antoniw, J. F., Nimmo, H. G., Yeaman, S. J. & Cohen, P.(1977) Biochem.J. 162, 423-433] were inhibited in a very similar manner by the protein phosphatase inhibitor and at least 95% inhibition was observed at high concentrations of inhibitor. The two forms of protein phosphatase-III, termed IIIA and IIIB, were equally susceptible to the protein phosphatase inhibitor. The protein phosphatase inhibitor was at least 200 times less effective in inhibiting the activity of protein phosphatase-I and protein phosphatase-II. The high degree of specificity of the inhibitor for protein phosphatase-III was used to show that 90% of the phosphorylase phosphatase and glycogen synthase phosphatase activities measured in muscle extracts are catalysed by protein phosphatase-III. Protein phosphatase-III was tightly associated with the protein-glycogen complex that can be isolated from skeletal muscle, whereas the protein phosphatase inhibitor and protein phosphatase-II were not. The results provide further evidence that the enzyme that catalyses the dephosphorylation of the alpha-subunit of phosphorylase kinase (protein phosphatase-II) and the enzyme that catalyses the dephosphorylation of the beta-subunit of phosphorylase kinase (protein phosphatase-III) are distinct. The results suggest that the protein phosphatase inhibitor may be a useful probe for differentiating different classes of protein phosphatases in mammalian

  9. Multiple Functions of the Eya Phosphotyrosine Phosphatase

    PubMed Central

    2015-01-01

    Eyes absent (Eya), a protein conserved from plants to humans and best characterized as a transcriptional coactivator, is also the prototype for a novel class of eukaryotic aspartyl protein tyrosine phosphatases. This minireview discusses recent breakthroughs in elucidating the substrates and cellular events regulated by Eya's tyrosine phosphatase function and highlights some of the complexities, new questions, and surprises that have emerged from efforts to understand how Eya's unusual multifunctionality influences developmental regulation and signaling. PMID:26667035

  10. 21 CFR 864.7660 - Leukocyte alkaline phosphatase test.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Leukocyte alkaline phosphatase test. 864.7660... Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte alkaline phosphatase test is a device used to identify the enzyme leukocyte alkaline phosphatase in neutrophilic granulocytes...

  11. 21 CFR 864.7660 - Leukocyte alkaline phosphatase test.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leukocyte alkaline phosphatase test. 864.7660... Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte alkaline phosphatase test is a device used to identify the enzyme leukocyte alkaline phosphatase in neutrophilic granulocytes...

  12. Analysis of Smad Phosphatase Activity In Vitro.

    PubMed

    Shen, Tao; Qin, Lan; Lin, Xia

    2016-01-01

    Phosphorylation of Smad1/5/8 at the C-terminal SXS motif by BMP type I receptors is one of the most critical events in BMP signaling. Conversely, protein phosphatases that dephosphorylate phospho-Smad1/5/8 can consequently prevent or terminate BMP signaling. PPM1H is an undercharacterized phosphatase in the PPM family. We recently demonstrated that PPM1H can dephosphorylate Smad1 in the cytoplasm and block BMP signaling responses in cellular assays. Here we describe in vitro method showing that PPM1H is a bona fide phosphatase for Smad1/5/8. PPM1H is produced as GST fusion protein in E. coli, and purified against glutathione sepharose beads. Bacterially purified recombinant PPM1H possesses phosphatase activity toward artificial substrate para-nitrophenyl phosphate (pNPP). Recombinant PPM1H also dephosphorylates immuno-purified phosphorylated Smad1 in test tubes. These direct in vitro phosphatase assays provide convincing evidence demonstrating the role of PPM1H as a specific phosphatase for P-Smad1. PMID:26520120

  13. Assessing the Biological Activity of the Glucan Phosphatase Laforin.

    PubMed

    Romá-Mateo, Carlos; Raththagala, Madushi; Gentry, Mathew S; Sanz, Pascual

    2016-01-01

    Glucan phosphatases are a recently discovered family of enzymes that dephosphorylate either starch or glycogen and are essential for proper starch metabolism in plants and glycogen metabolism in humans. Mutations in the gene encoding the only human glucan phosphatase, laforin, result in the fatal, neurodegenerative, epilepsy known as Lafora disease. Here, we describe phosphatase assays to assess both generic laforin phosphatase activity and laforin's unique glycogen phosphatase activity. PMID:27514803

  14. Protein Phosphatase 1 β Paralogs Encode the Zebrafish Myosin Phosphatase Catalytic Subunit

    PubMed Central

    Jayashankar, Vaishali; Nguyen, Michael J.; Carr, Brandon W.; Zheng, Dale C.; Rosales, Joseph B.; Rosales, Joshua B.; Weiser, Douglas C.

    2013-01-01

    Background The myosin phosphatase is a highly conserved regulator of actomyosin contractility. Zebrafish has emerged as an ideal model system to study the in vivo role of myosin phosphatase in controlling cell contractility, cell movement and epithelial biology. Most work in zebrafish has focused on the regulatory subunit of the myosin phosphatase called Mypt1. In this work, we examined the critical role of Protein Phosphatase 1, PP1, the catalytic subunit of the myosin phosphatase. Methodology/Principal Findings We observed that in zebrafish two paralogous genes encoding PP1β, called ppp1cba and ppp1cbb, are both broadly expressed during early development. Furthermore, we found that both gene products interact with Mypt1 and assemble an active myosin phosphatase complex. In addition, expression of this complex results in dephosphorylation of the myosin regulatory light chain and large scale rearrangements of the actin cytoskeleton. Morpholino knock-down of ppp1cba and ppp1cbb results in severe defects in morphogenetic cell movements during gastrulation through loss of myosin phosphatase function. Conclusions/Significance Our work demonstrates that zebrafish have two genes encoding PP1β, both of which can interact with Mypt1 and assemble an active myosin phosphatase. In addition, both genes are required for convergence and extension during gastrulation and correct dosage of the protein products is required. PMID:24040418

  15. Synthesis of benzopentathiepin analogs and their evaluation as inhibitors of the phosphatase STEP

    PubMed Central

    Baguley, Tyler D.; Nairn, Angus C.; Lombroso, Paul J.; Ellman, Jonathan A.

    2015-01-01

    Striatal-enriched protein tyrosine phosphatase (STEP) is a brain specific protein tyrosine phosphatase that has been implicated in many neurodegenerative diseases, such as Alzheimer’s disease. We recently reported the benzopentathiepin TC-2153 as a potent inhibitor of STEP in vitro, cells and animals. Herein, we report the synthesis and evaluation of TC-2153 analogs in order to define what structural features are important for inhibition and to identify positions tolerant of substitution for further study. The trifluoromethyl substitution is beneficial for inhibitor potency, and the amine is tolerant of acylation, and thus provides a convenient handle for introducing additional functionality such as reporter groups. PMID:25666825

  16. Bacterial-like PPP protein phosphatases

    PubMed Central

    Kerk, David; Uhrig, R Glen; Moorhead, Greg B

    2013-01-01

    Reversible phosphorylation is a widespread modification affecting the great majority of eukaryotic cellular proteins, and whose effects influence nearly every cellular function. Protein phosphatases are increasingly recognized as exquisitely regulated contributors to these changes. The PPP (phosphoprotein phosphatase) family comprises enzymes, which catalyze dephosphorylation at serine and threonine residues. Nearly a decade ago, “bacterial-like” enzymes were recognized with similarity to proteins from various bacterial sources: SLPs (Shewanella-like phosphatases), RLPHs (Rhizobiales-like phosphatases), and ALPHs (ApaH-like phosphatases). A recent article from our laboratory appearing in Plant Physiology characterizes their extensive organismal distribution, abundance in plant species, predicted subcellular localization, motif organization, and sequence evolution. One salient observation is the distinct evolutionary trajectory followed by SLP genes and proteins in photosynthetic eukaryotes vs. animal and plant pathogens derived from photosynthetic ancestors. We present here a closer look at sequence data that emphasizes the distinctiveness of pathogen SLP proteins and that suggests that they might represent novel drug targets. A second observation in our original report was the high degree of similarity between the bacterial-like PPPs of eukaryotes and closely related proteins of the “eukaryotic-like” phyla Myxococcales and Planctomycetes. We here reflect on the possible implications of these observations and their importance for future research. PMID:24675170

  17. Structure-Function Analysis of the 3' Phosphatase Component of T4 Polynucleotide Kinase/phosphatase

    SciTech Connect

    Zhu,H.; Smith, P.; Wang, L.; Shuman, S.

    2007-01-01

    T4 polynucleotide kinase/phosphatase (Pnkp) exemplifies a family of bifunctional enzymes with 5'-kinase and 3' phosphatase activities that function in nucleic acid repair. T4 Pnkp is a homotetramer of a 301-aa polypeptide, which consists of an N-terminal kinase domain of the P-loop phosphotransferase superfamily and a C-terminal phosphatase domain of the DxD acylphosphatase superfamily. The homotetramer is formed via pairs of phosphatase-phosphatase and kinase-kinase homodimer interfaces. Here we identify four side chains-Asp187, Ser211, Lys258, and Asp277-that are required for 3' phosphatase activity. Alanine mutations at these positions abolished phosphatase activity without affecting kinase function or tetramerization. Conservative substitutions of asparagine or glutamate for Asp187 did not revive the 3' phosphatase, nor did arginine or glutamine substitutions for Lys258. Threonine in lieu of Ser211 and glutamate in lieu of Asp277 restored full activity, whereas asparagine at position 277 had no salutary effect. We report a 3.0 A crystal structure of the Pnkp tetramer, in which a sulfate ion is coordinated between Arg246 and Arg279 in a position that we propose mimics one of the penultimate phosphodiesters (5'NpNpNp-3') of the polynucleotide 3'-PO(4) substrate. The amalgam of mutational and structural data engenders a plausible catalytic mechanism for the phosphatase that includes covalent catalysis (via Asp165), general acid-base catalysis (via Asp167), metal coordination (by Asp165, Asp277 and Asp278), and transition state stabilization (via Lys258, Ser211, backbone amides, and the divalent cation). Other critical side chains play architectural roles (Arg176, Asp187, Arg213, Asp254). To probe the role of oligomerization in phosphatase function, we introduced six double-alanine cluster mutations at the phosphatase-phosphatase domain interface, two of which (R297A-Q295A and E292A-D300A) converted Pnkp from a tetramer to a dimer and ablated phosphatase activity.

  18. Effect of cobalt on synthesis and activation of Bacillus licheniformis alkaline phosphatase.

    PubMed Central

    Spencer, D B; Chen, C P; Hulett, F M

    1981-01-01

    The effect of CO2+ on the synthesis and activation of Bacillus licheniformis MC14 alkaline phosphatase has been shown by the development of a defined minimal salts medium in which this organism produces 35 times more (assayable) alkaline phosphatase than when grown in a low-phosphate complex medium or in the defined medium without cobalt. Stimulation of enzyme activity with cobalt is dependent on a low phosphate concentration in the medium (below 0.075 mM) and continued protein synthesis. Cobalt stimulation resulted in alkaline phosphate production being a major portion of total protein synthesized during late-logarithmic and early-stationary-phase culture growth. Cells cultured in the defined medium minus cobalt, or purified enzyme partially inactivated with a chelating agent, showed a 2.5-fold increase in activity when assayed in the presence of cobalt. Atomic spectral analysis indicated the presence of 3.65 +/- 0.45 g-atoms of cobalt associated with each mole of purified active alkaline phosphatase. A biochemical localization as a function of culture age in this medium showed that alkaline phosphatase was associated with the cytoplasmic membrane and was also found as a soluble enzyme in the periplasmic region and secreted into the growth medium. PMID:7462163

  19. Effect of cobalt on synthesis and activation of Bacillus licheniformis alkaline phosphatase.

    PubMed

    Spencer, D B; Chen, C P; Hulett, F M

    1981-02-01

    The effect of CO2+ on the synthesis and activation of Bacillus licheniformis MC14 alkaline phosphatase has been shown by the development of a defined minimal salts medium in which this organism produces 35 times more (assayable) alkaline phosphatase than when grown in a low-phosphate complex medium or in the defined medium without cobalt. Stimulation of enzyme activity with cobalt is dependent on a low phosphate concentration in the medium (below 0.075 mM) and continued protein synthesis. Cobalt stimulation resulted in alkaline phosphate production being a major portion of total protein synthesized during late-logarithmic and early-stationary-phase culture growth. Cells cultured in the defined medium minus cobalt, or purified enzyme partially inactivated with a chelating agent, showed a 2.5-fold increase in activity when assayed in the presence of cobalt. Atomic spectral analysis indicated the presence of 3.65 +/- 0.45 g-atoms of cobalt associated with each mole of purified active alkaline phosphatase. A biochemical localization as a function of culture age in this medium showed that alkaline phosphatase was associated with the cytoplasmic membrane and was also found as a soluble enzyme in the periplasmic region and secreted into the growth medium. PMID:7462163

  20. Mycobacterium avium subsp. paratuberculosis PtpA Is an Endogenous Tyrosine Phosphatase Secreted during Infection▿

    PubMed Central

    Bach, Horacio; Sun, Jim; Hmama, Zakaria; Av-Gay, Yossef

    2006-01-01

    Adaptive gene expression in prokaryotes is mediated by protein kinases and phosphatases. These regulatory proteins mediate phosphorylation of histidine or aspartate in two-component systems and serine/threonine or tyrosine in eukaryotic and eukaryote-like protein kinase systems. The genome sequence of Mycobacterium avium subsp. paratuberculosis, the causative agent of Johne's disease, does not possess a defined tyrosine kinase. Nevertheless, it encodes for protein tyrosine phosphatases. Here, we report that Map1985, is a functional low-molecular tyrosine phosphatase that is secreted intracellularly upon macrophage infection. This finding suggests that Map1985 might contribute to the pathogenesis of Mycobacterium avium subsp. paratuberculosis by dephosphorylating essential macrophage signaling and/or adaptor molecules. PMID:16982836

  1. Lymphocyte phosphatase-associated phosphoprotein proteoforms analyzed using monoclonal antibodies

    PubMed Central

    Filatov, Alexander; Kruglova, Natalia; Meshkova, Tatiana; Mazurov, Dmitriy

    2015-01-01

    Phosphatase CD45 regulates the activation of lymphocytes by controlling the level of receptor and signal molecule phosphorylation. However, it remains unknown which molecules mediate the phosphatase activity of CD45. A candidate for such a molecule is a small transmembrane adapter protein called lymphocyte phosphatase-associated phosphoprotein (LPAP). LPAP forms a supramolecular complex that consists of not only CD45 molecule but also CD4 and Lck kinase. The function of LPAP has not been defined clearly. In our study, we determined the pattern of LPAP expression in various cell types and characterized its proteoforms using new monoclonal antibodies generated against the intracellular portion of the protein. We show that LPAP is a pan-lymphocyte marker, and its expression in cells correlates with the expression of CD45. The majority of T, B and NK cells express high levels of LPAP, whereas monocytes, granulocytes, monocyte-derived dendritic cells, platelets and red blood cells are negative for LPAP. Using one- and two-dimensional protein gel electrophoresis, we demonstrate that LPAP has at least four sites of phosphorylation. The resting cells express at least six different LPAP phosphoforms representing mono-, di- and tri-phosphorylated LPAP. T and B cells differ in the distribution of the protein between phosphoforms. The activation of lymphocytes with PMA reduces the diversity of phosphorylated forms. Our experiments on Lck-deficient Jurkat cells show that Lck kinase is not involved in LPAP phosphorylation. Thus, LPAP is a dynamically phosphorylated protein, the function of which can be understood, when all phosphosites and kinases involved in its phosphorylation will be identified. PMID:26682052

  2. Dephosphorylation of Tctex2-related dynein light chain by type 2A protein phosphatase.

    PubMed

    Inaba, Kazuo

    2002-10-01

    Sperm flagellar movements are regulated by cAMP-dependent protein phosphorylation. Tctex2-related light chain of outer arm dynein is a well-defined phosphorylated protein that is phosphorylated at activation of sperm motility. Here, the protein phosphatase that dephosphorylates Tctex2-related dynein light chain (LC2) has been characterized in salmonid fish sperm. Most of the phosphatase activity against LC2 is found in Triton-soluble fraction of flagella but trace extent of the activity is retained in the axoneme. The dephosphorylation of LC2 is inhibited by okadaic acid at more than 1nM, whereas that of dynein alpha heavy chain is inhibited at more than 10nM. The addition of Ca(2+) gives no direct effect on LC2 dephosphorylation, but it accelerates the dephosphorylation of the regulatory subunit of cAMP-dependent protein kinase, resulting in the decrease of LC2 phosphorylation. The activity to dephosphorylate the LC2 is separated by MonoQ ion-exchange column chromatography along with the immunoreactivity to the antibody against the catalytic subunit of type 2A protein phosphatase. These results suggest that LC2 is dephosphorylated by type 2A protein phosphatase and that dynein alpha heavy chain and the regulatory subunit of cAMP-dependent protein kinase are dephosphorylated by other types of protein phosphatases. PMID:12359223

  3. Structure of human PIR1, an atypical dual-specificity phosphatase.

    PubMed

    Sankhala, Rajeshwer Singh; Lokareddy, Ravi Kumar; Cingolani, Gino

    2014-02-11

    PIR1 is an atypical dual-specificity phosphatase (DSP) that dephosphorylates RNA with a higher specificity than phosphoproteins. Here we report the atomic structure of a catalytically inactive mutant (C152S) of the human PIR1 phosphatase core (PIR1-core, residues 29-205), refined at 1.20 Å resolution. PIR1-core shares structural similarities with DSPs related to Vaccinia virus VH1 and with RNA 5'-phosphatases such as the baculovirus RNA triphosphatase and the human mRNA capping enzyme. The PIR1 active site cleft is wider and deeper than that of VH1 and contains two bound ions: a phosphate trapped above the catalytic cysteine C152 exemplifies the binding mode expected for the γ-phosphate of RNA, and ∼6 Å away, a chloride ion coordinates the general base R158. Two residues in the PIR1 phosphate-binding loop (P-loop), a histidine (H154) downstream of C152 and an asparagine (N157) preceding R158, make close contacts with the active site phosphate, and their nonaliphatic side chains are essential for phosphatase activity in vitro. These residues are conserved in all RNA 5'-phosphatases that, analogous to PIR1, lack a "general acid" residue. Thus, a deep active site crevice, two active site ions, and conserved P-loop residues stabilizing the γ-phosphate of RNA are defining features of atypical DSPs that specialize in dephosphorylating 5'-RNA. PMID:24447265

  4. Phosphatase hydrolysis of organic phosphorus compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphatases are diverse groups of enzymes that deserve special attention because of the significant roles they play in mineralizing organic phosphorus (P) into inorganic available form. For getting more insight on the enzymatically hydrolysis of organic P, in this work, we compared the catalytic pa...

  5. Phosphatase activities as biosignatures of extant life

    NASA Astrophysics Data System (ADS)

    Kobayashi, K.; Itoh, Y.; Edazawa, Y.; Moroi, A.; Takano, Y.

    It has been recognized that terrestrial biosphere expands to such extreme environments as deep subsurface lithosphere high temperature hot springs and stratosphere Possible extraterrestrial biospheres in Mars Europa and Titan are being discussed Many biosignatures or biomarkers have been proposed to detect microbial activities in such extreme environments Phosphate esters are essential for the terrestrial life since they are constituents of nucleic acids and cell mebranes Thus all the terrestrial organisms have phosphatases that are enzymes catalyzing hydrolysis of phosphate esters We analyzed phosphatase activities in the samples obtained in extreme environments such as submarine hydrothermal systems and discussed whether they can be used as biosignatures for extant life Core samples and chimney samples were collected at the Suiyo Seamount Izu-Bonin Arc the Pacific Ocean in 2001 and 2002 and in South Mariana hydrothermal systems the Pacific Oceanas in 2003 both in a part of the Archaean Park Project Phosphatase activity in solid rock samples was measured spectrometrically by using 25 mM p-nitrophenyl phosphate pH 8 0 or pH 6 5 as a substrate as follows Pulverized samples were incuvated with substrate solution for an hour and then production rate of p-nitrophenol was calculated with absorbance at 410 nm Phosphatase activity in extracts was measured fluorometrically by using 4-methylumberyferryl phosphate as a substrate Concentration of amino acids and their enantiomeric ratio were determined by HPLC after HF digestion of the

  6. Decoding signals for membrane protein assembly using alkaline phosphatase fusions.

    PubMed Central

    McGovern, K; Ehrmann, M; Beckwith, J

    1991-01-01

    We have used genetic methods to investigate the role of the different domains of a bacterial cytoplasmic membrane protein, MalF, in determining its topology. This was done by analyzing the effects of MalF topology of deleting various domains of the protein using MalF-alkaline phosphatase fusion proteins. Our results show that the cytoplasmic domains of the protein are the pre-eminent topogenic signals. These domains contain information that determines their cytoplasmic location and, thus, the orientation of the membrane spanning segments surrounding them. Periplasmic domains do not appear to have equivalent information specifying their location and membrane spanning segments do not contain information defining their orientation in the membrane. The strength of cytoplasmic domains as topogenic signals varies, correlated with the density of positively charged amino acids within them. Images PMID:1915262

  7. Smooth-muscle caldesmon phosphatase is SMP-I, a type 2A protein phosphatase.

    PubMed

    Pato, M D; Sutherland, C; Winder, S J; Walsh, M P

    1993-07-01

    Caldesmon phosphatase was identified in chicken gizzard smooth muscle by using as substrates caldesmon phosphorylated at different sites by protein kinase C, Ca2+/calmodulin-dependent protein kinase II and cdc2 kinase. Most (approximately 90%) of the phosphatase activity was recovered in the cytosolic fraction. Gel filtration after (NH4)2SO4 fractionation of the cytosolic fraction revealed a single major peak of phosphatase activity which coeluted with calponin phosphatase [Winder, Pato and Walsh (1992) Biochem. J. 286, 197-203] and myosin LC20 phosphatase. Further purification of caldesmon phosphatase was achieved by sequential chromatography on columns of DEAE-Sephacel, omega-amino-octyl-agarose, aminopropyl-agarose and thiophosphorylated myosin LC20-Sepharose. A single peak of caldesmon phosphatase activity was detected at each step of the purification. The purified phosphatase was identified as SMP-I [Pato and Adelstein (1980) J. Biol. Chem. 255, 6535-6538] by subunit composition (three subunits, of 60, 55 and 38 kDa) and Western blotting using antibodies against the holoenzyme which recognize all three subunits and antibodies specific for the 38 kDa catalytic subunit. SMP-I is a type 2A protein phosphatase [Pato, Adelstein, Crouch, Safer, Ingebritsen and Cohen (1983) Eur. J. Biochem. 132, 283-287; Winder et al. (1992), cited above]. Consistent with the conclusion that SMP-I is the major caldesmon phosphatase of smooth muscle, purified SMP-I from turkey gizzard dephosphorylated all three phosphorylated forms of caldesmon, whereas SMP-II, -III and -IV were relatively ineffective. Kinetic analysis of dephosphorylation by chicken gizzard SMP-I of the three phosphorylated caldesmon species and calponin phosphorylated by protein kinase C indicates that calponin is a significantly better substrate of SMP-I than are any of the three phosphorylated forms of caldesmon. We therefore suggest that caldesmon phosphorylation in vivo can be maintained after kinase

  8. Assessment and kinetics of soil phosphatase in Brazilian Savanna systems.

    PubMed

    Ferreira, Adão S; Espíndola, Suéllen P; Campos, Maria Rita C

    2016-05-31

    The activity and kinetics of soil phosphatases are important indicators to evaluate soil quality in specific sites such as the Cerrado (Brazilian Savanna). This study aimed to determine the activity and kinetic parameters of soil phosphatase in Cerrado systems. Soil phosphatase activity was assessed in samples of native Cerrado (NC), no-tillage (NT), conventional tillage (CT) and pasture with Brachiaria brizantha (PBb) and evaluated with acetate buffer (AB), tris-HCl buffer (TB), modified universal buffer (MUB) and low MUB. The Michaelis-Menten equation and Eadie-Hofstee model were applied to obtain the kinetic parameters of soil phosphatase using different concentrations of p-nitrophenol phosphate (p-NPP). MUB showed the lowest soil phosphatase activity in all soils whereas AB in NC and NT presented the highest. Low MUB decreased interferences in the assessment of soil phosphatase activity when compared to MUB, suggesting that organic acids interfere on the soil phosphatase activity. In NC and NT, soil phosphatase activity performed with TB was similar to AB and low MUB. Km values from the Michaels-Menten equation were higher in NC than in NT, which indicate a lower affinity of phosphatase activity for the substrate in NC. Vmax values were also higher in NC than in NT. The Eadie-Hofstee model suggests that NC had more phosphatase isoforms than NT. The study showed that buffer type is of fundamental importance when assessing soil phosphatase activity in Cerrado soils. PMID:27254453

  9. [ATPase and phosphatase activity of drone brood].

    PubMed

    Bodnarchuk, L I; Stakhman, O S

    2004-01-01

    Most researches on insect enzymes concern carbohydrate and nitrogenous exchange. Data on ATPase activity for larval material of drone brood are absent in the available literature. The drone brood is one of the least investigated apiproducts. Allowing for the important role of ATPase in the vital functions of the insect cells our work was aimed at the study of ATPase of the drone blood activity and that of alkaline and acid phosphatases. When studying liophylised preparations of the drone brood homogenate we have found out high activity of Mg2+, Na+, K+-, Ca2+- and Mg2+-ATPase and of alkaline and acid phosphatase, that is the possible explanation of the high-intensity power and plastic processes proceeding during growth and development of larvae. PMID:16350755

  10. Rhizobiales-like Phosphatase 2 from Arabidopsis thaliana Is a Novel Phospho-tyrosine-specific Phospho-protein Phosphatase (PPP) Family Protein Phosphatase.

    PubMed

    Uhrig, R Glen; Labandera, Anne-Marie; Muhammad, Jamshed; Samuel, Marcus; Moorhead, Greg B

    2016-03-11

    Cellular signaling through protein tyrosine phosphorylation is well established in mammalian cells. Although lacking the classic tyrosine kinases present in humans, plants have a tyrosine phospho-proteome that rivals human cells. Here we report a novel plant tyrosine phosphatase from Arabidopsis thaliana (AtRLPH2) that, surprisingly, has the sequence hallmarks of a phospho-serine/threonine phosphatase belonging to the PPP family. Rhizobiales/Rhodobacterales/Rhodospirillaceae-like phosphatases (RLPHs) are conserved in plants and several other eukaryotes, but not in animals. We demonstrate that AtRLPH2 is localized to the plant cell cytosol, is resistant to the classic serine/threonine phosphatase inhibitors okadaic acid and microcystin, but is inhibited by the tyrosine phosphatase inhibitor orthovanadate and is particularly sensitive to inhibition by the adenylates, ATP and ADP. AtRLPH2 displays remarkable selectivity toward tyrosine-phosphorylated peptides versus serine/threonine phospho-peptides and readily dephosphorylates a classic tyrosine phosphatase protein substrate, suggesting that in vivo it is a tyrosine phosphatase. To date, only one other tyrosine phosphatase is known in plants; thus AtRLPH2 represents one of the missing pieces in the plant tyrosine phosphatase repertoire and supports the concept of protein tyrosine phosphorylation as a key regulatory event in plants. PMID:26742850

  11. The Extended Family of Protein Tyrosine Phosphatases.

    PubMed

    Alonso, Andrés; Nunes-Xavier, Caroline E; Bayón, Yolanda; Pulido, Rafael

    2016-01-01

    In higher eukaryotes, the Tyr phosphorylation status of cellular proteins results from the coordinated action of Protein Tyrosine Kinases (PTKs) and Protein Tyrosine Phosphatases (PTPs). PTPs have emerged as highly regulated enzymes with diverse substrate specificity, and proteins with Tyr-dephosphorylation or Tyr-dephosphorylation-like properties can be clustered as the PTPome. This includes proteins from the PTP superfamily, which display a Cys-based catalytic mechanism, as well as enzymes from other gene families (Asp-based phosphatases, His-based phosphatases) that have converged in protein Tyr-dephosphorylation-related functions by using non-Cys-based catalytic mechanisms. Within the Cys-based members of the PTPome, classical PTPs dephosphorylate specific phosphoTyr (pTyr) residues from protein substrates, whereas VH1-like dual-specificity PTPs dephosphorylate pTyr, pSer, and pThr residues, as well as nonproteinaceous substrates, including phosphoinositides and phosphorylated carbohydrates. In addition, several PTPs have impaired catalytic activity as a result of amino acid substitutions at their active sites, but retain regulatory functions related with pTyr signaling. As a result of their relevant biological activity, many PTPs are linked to human disease, including cancer, neurodevelopmental, and metabolic diseases, making these proteins important drug targets and molecular markers in the clinic. Here, a brief overview on the biochemistry and physiology of the different groups of proteins that belong to the mammalian PTPome is presented. PMID:27514797

  12. Leishmanial phosphatase hydrolyzes phosphoproteins and inositol phosphates

    SciTech Connect

    Saha, A.K.; Das, S.; Glew, R.H.

    1986-05-01

    An extensively purified preparation of the predominant, tartrate-resistant acid phosphatase (ACP) from the external surface of Leishmania donovani promastigotes form catalyzes the dephosphorylation of several phosphoproteins; these include: pyruvate kinase, phosphorylase kinase and histones. However, the protein phosphatase activity of ACP is very low compared with that of other protein phosphates known to be involved in regulating various metabolic pathways. /sup 32/P-labelled inositoltriphosphate (IP3), a well-established second messenger derived from phosphatidylinositol-4,5-diphosphate (PIP2), was a substrate for the leishmanial acid phosphatase; incubation of the IP3 preparation with 13.2 milliunits (1 unit equals 1 ..mu..mol 4-methylumbelliferyl phosphate (MUP) cleaved per min at pH 5.5) of ACP at pH 5.5 for 4 hr resulted in hydrolysis of 75% of the radiolabelled substrate resulting in a mixture of inositoldiphosphate and inositolmonophosphate. In addition PIP2 was hydrolyzed rapidly by ACP at pH 5.5 (V/sub max/, 71 units/mg protein; k/sub m/, 4.16 ..mu..M). In contrast, to MUP which is hydrolzyed most rapidly at pH 5.5, PIP2 hydrolysis was optimal at pH 6.8. These observations raise the possibility that ACP could play a role in the host-phagocyte interaction by degrading the precursor of the second messenger, PIP2 or the second messenger itself, IP3.

  13. Role of Protein Tyrosine Phosphatases in Plants

    PubMed Central

    Shankar, Alka; Agrawal, Nisha; Sharma, Manisha; Pandey, Amita; Pandey, Girdhar K.

    2015-01-01

    Reversible protein phosphorylation is a crucial regulatory mechanism that controls many biological processes in eukaryotes. In plants, phosphorylation events primarily occur on serine (Ser) and threonine (Thr) residues, while in certain cases, it was also discovered on tyrosine (Tyr) residues. In contrary to plants, extensive reports on Tyr phosphorylation regulating a large numbers of biological processes exist in animals. Despite of such prodigious function in animals, Tyr phosphorylation is a least studied mechanism of protein regulation in plants. Recently, various chemical analytical procedures have strengthened the view that Tyr phosphorylation is equally prevalent in plants as in animals. However, regardless of Tyr phosphorylation events occuring in plants, no evidence could be found for the existence of gene encoding for Tyr phosphorylation i.e. the typical Tyr kinases. Various methodologies have suggested that plant responses to stress signals and developmental processes involved modifications in protein Tyr phosphorylation. Correspondingly, various reports have established the role of PTPs (Protein Tyrosine Phosphatases) in the dephosphorylation and inactivation of mitogen activated protein kinases (MAPKs) hence, in the regulation of MAPK signaling cascade. Besides this, many dual specificity protein phosphatases (DSPs) are also known to bind starch and regulate starch metabolism through reversible phosphorylation. Here, we are emphasizing the significant progress on protein Tyr phosphatases to understand the role of these enzymes in the regulation of post-translational modification in plant physiology and development. PMID:26962298

  14. Regulatory Roles of MAPK Phosphatases in Cancer

    PubMed Central

    Low, Heng Boon

    2016-01-01

    The mitogen-activated protein kinases (MAPKs) are key regulators of cell growth and survival in physiological and pathological processes. Aberrant MAPK signaling plays a critical role in the development and progression of human cancer, as well as in determining responses to cancer treatment. The MAPK phosphatases (MKPs), also known as dual-specificity phosphatases (DUSPs), are a family of proteins that function as major negative regulators of MAPK activities in mammalian cells. Studies using mice deficient in specific MKPs including MKP1/DUSP1, PAC-1/DUSP2, MKP2/DUSP4, MKP5/DUSP10 and MKP7/DUSP16 demonstrated that these molecules are important not only for both innate and adaptive immune responses, but also for metabolic homeostasis. In addition, the consequences of the gain or loss of function of the MKPs in normal and malignant tissues have highlighted the importance of these phosphatases in the pathogenesis of cancers. The involvement of the MKPs in resistance to cancer therapy has also gained prominence, making the MKPs a potential target for anti-cancer therapy. This review will summarize the current knowledge of the MKPs in cancer development, progression and treatment outcomes. PMID:27162525

  15. Phosphatase PTP4A3 Promotes Triple-Negative Breast Cancer Growth and Predicts Poor Patient Survival.

    PubMed

    den Hollander, Petra; Rawls, Kathryn; Tsimelzon, Anna; Shepherd, Jonathan; Mazumdar, Abhijit; Hill, Jamal; Fuqua, Suzanne A W; Chang, Jenny C; Osborne, C Kent; Hilsenbeck, Susan G; Mills, Gordon B; Brown, Powel H

    2016-04-01

    Triple-negative breast cancer (TNBC) has the worst prognosis of all breast cancers, and women diagnosed with TNBC currently lack targeted treatment options. To identify novel targets for TNBC, we evaluated phosphatase expression in breast tumors and characterized their contributions to in vitro and in vivo growth of TNBC. Using Affymetrix microarray analysis of 102 breast cancers, we identified 146 phosphatases that were significantly differentially expressed in TNBC compared with estrogen receptor (ER)-positive tumors. Of these, 19 phosphatases were upregulated (0.66-fold; FDR = 0.05) in TNBC compared with ER-positive breast cancers. We knocked down 17 overexpressed phosphatases in four triple-negative and four ER-positive breast cancer lines using specific siRNAs and found that depletion of six of these phosphatases significantly reduced growth and anchorage-independent growth of TNBC cells to a greater extent than ER-positive cell lines. Further analysis of the phosphatase PTP4A3 (also known as PRL-3) demonstrated its requirement for G1-S cell-cycle progression in all breast cancer cells, but PTP4A3 regulated apoptosis selectively in TNBC cells. In addition, PTP4A3 inhibition reduced the growth of TNBC tumors in vivo Moreover, in silico analysis revealed the PTP4A3 gene to be amplified in 29% of basal-like breast cancers, and high expression of PTP4A3 could serve as an independent prognostic indicator for worse overall survival. Collectively, these studies define the importance of phosphatase overexpression in TNBC and lay the foundation for the development of new targeted therapies directed against phosphatases or their respective signaling pathways for TNBC patients. Cancer Res; 76(7); 1942-53. ©2016 AACR. PMID:26921331

  16. Carboxyarabinitol-1-P phosphatase of Phaseolus vulgaris

    SciTech Connect

    Kobza, J.; Moore, B.d.; Seemann, J.R. )

    1990-05-01

    The activity of carboxyarabinitol-1-P (CA1P) phosphatase was detected in clarified stromal extracts by the generation of {sup 14}C-carboxyarabinitol from {sup 14}C-CA1P. Carboxyribitol-1-P dependent activity was 3% of the CA1P dependent activity, indicating the enzyme was specific for CA1P. Inclusion of DTT in the assay was required for maximum velocity, but it appears that the enzyme is not regulated by thioredoxin in vivo. Activity o f the CA1P phosphatase was stimulated by RuBP, NADPH and FBP, though the latter two metabolites were required at nonphysiological concentrations in order to achieve significant stimulation. Contrary to a previous report on purified tobacco enzyme, ATP stimulated the CA1P phosphatase activity. In the presence of 1 mM RuBP or ATP, rates of 2 or 3 {mu}mol mg{sup {minus}1} Chl h{sup {minus}1}, respectively, were observed at 1 mM CA1P. These rates were 3-4 fold higher than the rate observed in the absence of effectors and are 2-4 times the in vivo rate of degradation of CA1P during dark/light transitions. The rates from bean were about 7 fold higher than rates reported for the enzyme from tobacco. Changes in the levels of ATP and RuBP associated with dark/light transitions could modulate the enzyme activity in vivo, but it remains to be established if this is the only mechanism for the required regulation of the enzyme.

  17. Protein-tyrosine Phosphatase and Kinase Specificity in Regulation of SRC and Breast Tumor Kinase* ♦

    PubMed Central

    Fan, Gaofeng; Aleem, Saadat; Yang, Ming; Miller, W. Todd; Tonks, Nicholas K.

    2015-01-01

    Despite significant evidence to the contrary, the view that phosphatases are “nonspecific” still pervades the field. Systems biology approaches to defining how signal transduction pathways are integrated at the level of whole organisms also often downplay the contribution of phosphatases, defining them as “erasers” that serve merely to restore the system to its basal state. Here, we present a study that counteracts the idea of “nonspecific phosphatases.” We have characterized two structurally similar and functionally related kinases, BRK and SRC, which are regulated by combinations of activating autophosphorylation and inhibitory C-terminal sites of tyrosine phosphorylation. We demonstrated specificity at the level of the kinases in that SRMS phosphorylated the C terminus of BRK, but not SRC; in contrast, CSK is the kinase responsible for C-terminal phosphorylation of SRC, but not BRK. For the phosphatases, we observed that RNAi-mediated suppression of PTP1B resulted in opposing effects on the activity of BRK and SRC and have defined the mechanisms underlying this specificity. PTP1B inhibited BRK by directly dephosphorylating the Tyr-342 autophosphorylation site. In contrast, PTP1B potentiated SRC activity, but not by dephosphorylating SRC itself directly; instead, PTP1B regulated the interaction between CBP/PAG and CSK. SRC associated with, and phosphorylated, the transmembrane protein CBP/PAG at Tyr-317, resulting in CSK recruitment. We identified PAG as a substrate of PTP1B, and dephosphorylation abolished recruitment of the inhibitory kinase CSK. Overall, these findings illustrate how the combinatorial effects of PTKs and PTPs may be integrated to regulate signaling, with both classes of enzymes displaying exquisite specificity. PMID:25897081

  18. Modulation of protein tyrosine phosphatase activity alters the subunit assembly in native N-methyl-D-aspartate receptor complex.

    PubMed

    Ferrani-Kile, Karima; Leslie, Steven W

    2005-07-01

    The N-methyl-D-aspartate (NMDA) receptor is crucial for development and neuroplasticity as well as excitotoxicity. The biochemical basis of the disassembly and reassembly of NMDA receptor has never been reported. Using coimmunoprecipitation, Western blotting, and mass spectrometry, we show that inhibition of tyrosine phosphatases triggers disassembly of NR1, NR2A, and NR2B in cortical NMDA receptor complexes. Furthermore, the disassembly of the NMDA receptor subunits is immediate, dose-dependent, and reversible and seems to occur through mechanisms linked to Src kinases. Together, these results define a novel role for tyrosine phosphatases in the complex mechanism of NMDA receptor regulation. PMID:15837820

  19. The extended human PTPome: a growing tyrosine phosphatase family.

    PubMed

    Alonso, Andrés; Pulido, Rafael

    2016-04-01

    Tyr phosphatases are, by definition, enzymes that dephosphorylate phospho-Tyr (pTyr) from proteins. This activity is found in several structurally diverse protein families, including the protein Tyr phosphatase (PTP), arsenate reductase, rhodanese, haloacid dehalogenase (HAD) and His phosphatase (HP) families. Most of these families include members with substrate specificity for non-pTyr substrates, such as phospho-Ser/phospho-Thr, phosphoinositides, phosphorylated carbohydrates, mRNAs, or inorganic moieties. A Cys is essential for catalysis in PTPs, rhodanese and arsenate reductase enzymes, whereas this work is performed by an Asp in HAD phosphatases and by a His in HPs, via a catalytic mechanism shared by all of the different families. The category that contains most Tyr phosphatases is the PTP family, which, although it received its name from this activity, includes Ser, Thr, inositide, carbohydrate and RNA phosphatases, as well as some inactive pseudophosphatase proteins. Here, we propose an extended collection of human Tyr phosphatases, which we call the extended human PTPome. The addition of new members (SACs, paladin, INPP4s, TMEM55s, SSU72, and acid phosphatases) to the currently categorized PTP group of enzymes means that the extended human PTPome contains up to 125 proteins, of which ~ 40 are selective for pTyr. We set criteria to ascribe proteins to the extended PTPome, and summarize the more important features of the new PTPome members in the context of their phosphatase activity and their relationship with human disease. PMID:26573778

  20. Bone alkaline phosphatase in rheumatic diseases.

    PubMed

    Beyeler, C; Banks, R E; Thompson, D; Forbes, M A; Cooper, E H; Bird, H

    1995-07-01

    A double monoclonal immunoradiometric assay specific for bone alkaline phosphatase (BAP) was used to determine whether the raised total alkaline phosphatase (TAP) often found in patients with active rheumatoid arthritis (RA) and ankylosing spondylitis (AS) is derived from bone or liver. Fifty-eight patients with RA were compared to 14 with AS and 14 with non-inflammatory rheumatic diseases (NI). None had clinical liver disease and only one had a slightly elevated aspartate transaminase activity. Elevated BAP concentrations were found in seven patients (5 RA, 1 AS, 1 NI), only two of whom also had abnormal TAP. Abnormal TAP activities were found in only three patients (all RA). BAP did not correlate with disease activity in RA or AS. In contrast, TAP correlated with disease activity (assessed by plasma viscosity) in RA (P < 0.002) and gamma-glutamyl transferase (GGT) also correlated with plasma viscosity in RA (P < 0.01). Both TAP and BAP were significantly correlated with GGT in RA (P < 0.001 and P < 0.02, respectively). These findings are discussed, together with possible reasons for the conflicting nature of some of the observations. PMID:7486797

  1. Histone II-A stimulates glucose-6-phosphatase and reveals mannose-6-phosphatase activities without permeabilization of liver microsomes.

    PubMed Central

    St-Denis, J F; Annabi, B; Khoury, H; van de Werve, G

    1995-01-01

    The effect of histone II-A on glucose-6-phosphatase and mannose-6-phosphatase activities was investigated in relation to microsomal membrane permeability. It was found that glucose-6-phosphatase activity in histone II-A-pretreated liver microsomes was stimulated to the same extent as in detergent-permeabilized microsomes, and that the substrate specificity of the enzyme for glucose 6-phosphate was lost in histone II-A-pretreated microsomes, as [U-14C]glucose-6-phosphate hydrolysis was inhibited by mannose 6-phosphate and [U-14C]mannose 6-phosphate hydrolysis was increased. The accumulation of [U-14C]glucose from [U-14C]glucose 6-phosphate into untreated microsomes was completely abolished in detergent-treated vesicles, but was increased in histone II-A-treated microsomes, accounting for the increased glucose-6-phosphatase activity, and demonstrating that the microsomal membrane was still intact. The stimulation of glucose-6-phosphatase and mannose-6-phosphatase activities by histone II-A was found to be reversed by EGTA. It is concluded that the effects of histone II-A on glucose-6-phosphatase and mannose-6-phosphatase are not caused by the permeabilization of the microsomal membrane. The measurement of mannose-6-phosphatase latency to evaluate the intactness of the vesicles is therefore inappropriate. PMID:7646448

  2. Phosphatase Specificity and Pathway Insulation in Signaling Networks

    PubMed Central

    Rowland, Michael A.; Harrison, Brian; Deeds, Eric J.

    2015-01-01

    Phosphatases play an important role in cellular signaling networks by regulating the phosphorylation state of proteins. Phosphatases are classically considered to be promiscuous, acting on tens to hundreds of different substrates. We recently demonstrated that a shared phosphatase can couple the responses of two proteins to incoming signals, even if those two substrates are from otherwise isolated areas of the network. This finding raises a potential paradox: if phosphatases are indeed highly promiscuous, how do cells insulate themselves against unwanted crosstalk? Here, we use mathematical models to explore three possible insulation mechanisms. One approach involves evolving phosphatase KM values that are large enough to prevent saturation by the phosphatase’s substrates. Although this is an effective method for generating isolation, the phosphatase becomes a highly inefficient enzyme, which prevents the system from achieving switch-like responses and can result in slow response kinetics. We also explore the idea that substrate degradation can serve as an effective phosphatase. Assuming that degradation is unsaturatable, this mechanism could insulate substrates from crosstalk, but it would also preclude ultrasensitive responses and would require very high substrate turnover to achieve rapid dephosphorylation kinetics. Finally, we show that adaptor subunits, such as those found on phosphatases like PP2A, can provide effective insulation against phosphatase crosstalk, but only if their binding to substrates is uncoupled from their binding to the catalytic core. Analysis of the interaction network of PP2A’s adaptor domains reveals that although its adaptors may isolate subsets of targets from one another, there is still a strong potential for phosphatase crosstalk within those subsets. Understanding how phosphatase crosstalk and the insulation mechanisms described here impact the function and evolution of signaling networks represents a major challenge for

  3. Sensing and signaling of oxidative stress in chloroplasts by inactivation of the SAL1 phosphoadenosine phosphatase.

    PubMed

    Chan, Kai Xun; Mabbitt, Peter D; Phua, Su Yin; Mueller, Jonathan W; Nisar, Nazia; Gigolashvili, Tamara; Stroeher, Elke; Grassl, Julia; Arlt, Wiebke; Estavillo, Gonzalo M; Jackson, Colin J; Pogson, Barry J

    2016-08-01

    Intracellular signaling during oxidative stress is complex, with organelle-to-nucleus retrograde communication pathways ill-defined or incomplete. Here we identify the 3'-phosphoadenosine 5'-phosphate (PAP) phosphatase SAL1 as a previously unidentified and conserved oxidative stress sensor in plant chloroplasts. Arabidopsis thaliana SAL1 (AtSAL1) senses changes in photosynthetic redox poise, hydrogen peroxide, and superoxide concentrations in chloroplasts via redox regulatory mechanisms. AtSAL1 phosphatase activity is suppressed by dimerization, intramolecular disulfide formation, and glutathionylation, allowing accumulation of its substrate, PAP, a chloroplast stress retrograde signal that regulates expression of plastid redox associated nuclear genes (PRANGs). This redox regulation of SAL1 for activation of chloroplast signaling is conserved in the plant kingdom, and the plant protein has evolved enhanced redox sensitivity compared with its yeast ortholog. Our results indicate that in addition to sulfur metabolism, SAL1 orthologs have evolved secondary functions in oxidative stress sensing in the plant kingdom. PMID:27432987

  4. Biogeochemical drivers of phosphatase activity in salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Freitas, Joana; Duarte, Bernardo; Caçador, Isabel

    2014-10-01

    Although nitrogen has become a major concern for wetlands scientists dealing with eutrophication problems, phosphorous represents another key element, and consequently its biogeochemical cycling has a crucial role in eutrophication processes. Microbial communities are a central component in trophic dynamics and biogeochemical processes on coastal systems, since most of the processes in sediments are microbial-mediated due to enzymatic action, including the mineralization of organic phosphorus carried out by acid phosphatase activity. In the present work, the authors investigate the biogeochemical sediment drivers that control phosphatase activities. Authors also aim to assess biogeochemical factors' influence on the enzyme-mediated phosphorous cycling processes in salt marshes. Plant rhizosediments and bare sediments were collected and biogeochemical features, including phosphatase activities, inorganic and organic phosphorus contents, humic acids content and pH, were assessed. Acid phosphatase was found to give the highest contribution for total phosphatase activity among the three pH-isoforms present in salt marsh sediments, favored by acid pH in colonized sediments. Humic acids also appear to have an important role inhibiting phosphatase activity. A clear relation of phosphatase activity and inorganic phosphorous was also found. The data presented reinforces the role of phosphatase in phosphorous cycling.

  5. Acid phosphatase deactivation by a series mechanism.

    PubMed

    Gianfreda, L; Marrucci, G; Grizzuti, N; Greco, G

    1984-05-01

    Acid phosphatase (E.C.3.1.3.2.) thermal deactivation at pH 3.77 has been investigated by monitoring the enzyme activity as a function of time in the hydrolysis of p-nitrophenyl phosphate. The experimental curves obtained show a two-slope behavior in a log (activity)versus-time plot, which indicates that deactivation occurs via a complex mechanism. From the dependence of the kinetic parameters on both deactivation and hydrolysis temperatures, it is inferred that the deactivation mechanism involves intermediate, temperature-dependent, less-active forms of the enzyme. This interpretation is confirmed by the results of additional tests in which the temperature was suddenly changed during the deactivation process. PMID:18553349

  6. Unique structural features of red kidney bean purple acid phosphatase.

    PubMed

    Cashikar, A G; Rao, M N

    1995-06-01

    Purple acid phosphatase from red kidney beans (Phaseolus vulgaris) has been purified to homogeneity and characterized. The enzyme is a homodimer of 60 kDa subunits each containing one atom of zinc and iron in the active site. Circular dichroism spectral studies on the purified enzyme reveals that a large portion of the peptide backbone is in the unordered and beta-turn conformation. A unique feature of the red kidney bean acid phosphatase, which we have found, is that one of the two cysteines of each subunit is involved in the formation of an inter-subunit disulphide. The thiol group of the other cysteine is not necessary for the activity of the enzyme. Western blot analysis with antibodies raised against kidney bean acid phosphatase could not recognize acid phosphatases from other sources except from potato. This paper emphasizes the fact that acid phosphatases are functionally, but not structurally, conserved enzymes. PMID:7590853

  7. Direct determination of phosphatase activity from physiological substrates in cells.

    PubMed

    Ren, Zhongyuan; Do, Le Duy; Bechkoff, Géraldine; Mebarek, Saida; Keloglu, Nermin; Ahamada, Saandia; Meena, Saurabh; Magne, David; Pikula, Slawomir; Wu, Yuqing; Buchet, René

    2015-01-01

    A direct and continuous approach to determine simultaneously protein and phosphate concentrations in cells and kinetics of phosphate release from physiological substrates by cells without any labeling has been developed. Among the enzymes having a phosphatase activity, tissue non-specific alkaline phosphatase (TNAP) performs indispensable, multiple functions in humans. It is expressed in numerous tissues with high levels detected in bones, liver and neurons. It is absolutely required for bone mineralization and also necessary for neurotransmitter synthesis. We provided the proof of concept that infrared spectroscopy is a reliable assay to determine a phosphatase activity in the osteoblasts. For the first time, an overall specific phosphatase activity in cells was determined in a single step by measuring simultaneously protein and substrate concentrations. We found specific activities in osteoblast like cells amounting to 116 ± 13 nmol min(-1) mg(-1) for PPi, to 56 ± 11 nmol min(-1) mg(-1) for AMP, to 79 ± 23 nmol min(-1) mg(-1) for beta-glycerophosphate and to 73 ± 15 nmol min(-1) mg(-1) for 1-alpha-D glucose phosphate. The assay was also effective to monitor phosphatase activity in primary osteoblasts and in matrix vesicles. The use of levamisole--a TNAP inhibitor--served to demonstrate that a part of the phosphatase activity originated from this enzyme. An IC50 value of 1.16 ± 0.03 mM was obtained for the inhibition of phosphatase activity of levamisole in osteoblast like cells. The infrared assay could be extended to determine any type of phosphatase activity in other cells. It may serve as a metabolomic tool to monitor an overall phosphatase activity including acid phosphatases or other related enzymes. PMID:25785438

  8. Phosphatidylinositol anchor of HeLa cell alkaline phosphatase

    SciTech Connect

    Jemmerson, R.; Low, M.G.

    1987-09-08

    Alkaline phosphatase from cancer cells, HeLa TCRC-1, was biosynthetically labeled with either /sup 3/H-fatty acids or (/sup 3/H)ethanolamine as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material. Phosphatidylinositol-specific phospholipase C (PI-PLC) released a substantial proportion of the /sup 3/H-fatty acid label from immunoaffinity-purified alkaline phosphatase but had no effect on the radioactivity of (/sup 3/H)ethanolamine-labeled material. PI-PLC also liberated catalytically active alkaline phosphatase from viable cells, and this could be selectively blocked by monoclonal antibodies to alkaline phosphatase. However, the alkaline phosphatase released from /sup 3/H-fatty acid labeled cells by PI-PLC was not radioactive. By contrast, treatment with bromelain removed both the /sup 3/H-fatty acid and the (/sup 3/H)ethanolamine label from purified alkaline phosphatase. Subtilisin was also able to remove the (/sup 3/H)ethanolamine label from the purified alkaline phosphatase. The /sup 3/H radioactivity in alkaline phosphatase purified from (/sup 3/H)ethanolamine-labeled cells comigrated with authentic (/sup 3/H)ethanolamine by anion-exchange chromatography after acid hydrolysis. The data suggest that the /sup 3/H-fatty acid and (/sup 3/H)ethanolamine are covalently attached to the carboxyl-terminal segment since bromelain and subtilisin both release alkaline phosphatase from the membrane by cleavage at that end of the polypeptide chain. The data are consistent with findings for other proteins recently shown to be anchored in the membrane through a glycosylphosphatidylinositol structure and indicate that a similar structure contributes to the membrane anchoring of alkaline phosphatase.

  9. Francisella DnaK Inhibits Tissue-nonspecific Alkaline Phosphatase*

    PubMed Central

    Arulanandam, Bernard P.; Chetty, Senthilnath Lakshmana; Yu, Jieh-Juen; Leonard, Sean; Klose, Karl; Seshu, Janakiram; Cap, Andrew; Valdes, James J.; Chambers, James P.

    2012-01-01

    Following pulmonary infection with Francisella tularensis, we observed an unexpected but significant reduction of alkaline phosphatase, an enzyme normally up-regulated following inflammation. However, no reduction was observed in mice infected with a closely related Gram-negative pneumonic organism (Klebsiella pneumoniae) suggesting the inhibition may be Francisella-specific. In similar fashion to in vivo observations, addition of Francisella lysate to exogenous alkaline phosphatase (tissue-nonspecific isozyme) was inhibitory. Partial purification and subsequent proteomic analysis indicated the inhibitory factor to be the heat shock protein DnaK. Incubation with increasing amounts of anti-DnaK antibody reduced the inhibitory effect in a dose-dependent manner. Furthermore, DnaK contains an adenosine triphosphate binding domain at its N terminus, and addition of adenosine triphosphate enhances dissociation of DnaK with its target protein, e.g. alkaline phosphatase. Addition of adenosine triphosphate resulted in decreased DnaK co-immunoprecipitated with alkaline phosphatase as well as reduction of Francisella-mediated alkaline phosphatase inhibition further supporting the binding of Francisella DnaK to alkaline phosphatase. Release of DnaK via secretion and/or bacterial cell lysis into the extracellular milieu and inhibition of plasma alkaline phosphatase could promote an orchestrated, inflammatory response advantageous to Francisella. PMID:22923614

  10. A Theileria parva type 1 protein phosphatase activity.

    PubMed

    Cayla, X; Garcia, A; Baumgartner, M; Ozon, R; Langsley, G

    2000-09-01

    The protozoan parasite Theileria (spp. parva and annulata) infects bovine leukocytes and provokes a leukaemia-like disease in vivo. In this study, we have detected a type 1 serine/threonine phosphatase activity with phosphorylase a as a substrate, in protein extracts of parasites purified from infected B lymphocytes. In contrast to this type 1 activity, dose response experiments with okadaic acid (OA), a well characterised inhibitor of type 1 and 2A protein phosphatases, indicated that type 2A is the predominant activity detected in host B cells. Furthermore, consistent with polycation-specific activation of the type 2A phosphatase, protamine failed to activate the parasite-associated phosphorylase a phosphatase activity. Moreover, inhibition of phosphorylase a dephosphorylation by phospho-DARPP-32, a specific type 1 inhibitor, clearly demonstrated that a type 1 phosphatase is specifically associated with the parasite, while the type 2A is predominantly expressed in the host lymphocyte. Since an antibody against bovine catalytic protein phosphatase 1 (PP1) subunit only recognised the PP1 in B cells, but not in parasite extracts, we conclude that in parasites the PP1 activity is of parasitic origin. Intriguingly, since type 1 OA-sensitive phosphatase activity has been recently described in Plasmodium falciparum, we can conclude that these medically important parasites produce their one PP1. PMID:10989153

  11. Biomineralization of uranium by PhoY phosphatase activity aids cell survival in Caulobacter crescentus.

    PubMed

    Yung, Mimi C; Jiao, Yongqin

    2014-08-01

    Caulobacter crescentus is known to tolerate high levels of uranium [U(VI)], but its detoxification mechanism is poorly understood. Here we show that C. crescentus is able to facilitate U(VI) biomineralization through the formation of U-Pi precipitates via its native alkaline phosphatase activity. The U-Pi precipitates, deposited on the cell surface in the form of meta-autunite structures, have a lower U/Pi ratio than do chemically produced precipitates. The enzyme that is responsible for the phosphatase activity and thus the biomineralization process is identified as PhoY, a periplasmic alkaline phosphatase with broad substrate specificity. Furthermore, PhoY is shown to confer a survival advantage on C. crescentus toward U(VI) under both growth and nongrowth conditions. Results obtained in this study thus highlight U(VI) biomineralization as a resistance mechanism in microbes, which not only improves our understanding of bacterium-mineral interactions but also aids in defining potential ecological niches for metal-resistant bacteria. PMID:24878600

  12. Biomineralization of Uranium by PhoY Phosphatase Activity Aids Cell Survival in Caulobacter crescentus

    PubMed Central

    Yung, Mimi C.

    2014-01-01

    Caulobacter crescentus is known to tolerate high levels of uranium [U(VI)], but its detoxification mechanism is poorly understood. Here we show that C. crescentus is able to facilitate U(VI) biomineralization through the formation of U-Pi precipitates via its native alkaline phosphatase activity. The U-Pi precipitates, deposited on the cell surface in the form of meta-autunite structures, have a lower U/Pi ratio than do chemically produced precipitates. The enzyme that is responsible for the phosphatase activity and thus the biomineralization process is identified as PhoY, a periplasmic alkaline phosphatase with broad substrate specificity. Furthermore, PhoY is shown to confer a survival advantage on C. crescentus toward U(VI) under both growth and nongrowth conditions. Results obtained in this study thus highlight U(VI) biomineralization as a resistance mechanism in microbes, which not only improves our understanding of bacterium-mineral interactions but also aids in defining potential ecological niches for metal-resistant bacteria. PMID:24878600

  13. Biomineralization of Uranium by PhoY Phosphatase Activity Aids Cell Survival in Caulobacter crescentus

    SciTech Connect

    Yung, M C; Jiao, Y

    2014-07-22

    Caulobacter crescentus is known to tolerate high levels of uranium [U(VI)], but its detoxification mechanism is poorly understood. Here we show that C. crescentus is able to facilitate U(VI) biomineralization through the formation of U-Pi precipitates via its native alkaline phosphatase activity. The U-Pi precipitates, deposited on the cell surface in the form of meta-autunite structures, have a lower U/Pi ratio than do chemically produced precipitates. The enzyme that is responsible for the phosphatase activity and thus the biomineralization process is identified as PhoY, a periplasmic alkaline phosphatase with broad substrate specificity. Furthermore, PhoY is shown to confer a survival advantage on C. crescentus toward U(VI) under both growth and nongrowth conditions. Results obtained in this study thus highlight U(VI) biomineralization as a resistance mechanism in microbes, which not only improves our understanding of bacterium-mineral interactions but also aids in defining potential ecological niches for metal-resistant bacteria.

  14. Promiscuous sulfatase activity and thio-effects in a phosphodiesterase of the alkaline phosphatase superfamily†

    PubMed Central

    Lassila, Jonathan K.; Herschlag, Daniel

    2009-01-01

    The nucleotide phosphodiesterase/pyrophosphatase from Xanthomonas axonopodis (NPP) is a structural and evolutionary relative of alkaline phosphatase that preferentially hydrolyzes phosphate diesters. With the goal of understanding how these two enzymes with nearly identical Zn2+ bimetallo sites achieve high selectivity for hydrolysis of either phosphate monoesters or diesters, we have measured a promiscuous sulfatase activity in NPP. Sulfate esters are nearly isosteric with phosphate esters but carry less charge, offering a probe of electrostatic contributions to selectivity. NPP exhibits sulfatase activity with kcat/KM value of 2 × 10−5 M−1s−1, similar to the R166S mutant of alkaline phosphatase. We further report the effects of thio-substitution on phosphate monoester and diester reactions. Reactivities with these non-cognate substrates illustrate a reduced dependence of NPP reactivity on the charge of the nonbridging oxygen situated between the Zn2+ ions relative to that in alkaline phosphatase. This reduced charge dependence can explain about 102 of the 107-fold differential catalytic proficiency for the most similar monoester and diester substrates in the two enzymes. The results further suggest that active site contacts to substrate oxygen atoms that do not contact the Zn2+ ions may play an important role in defining the selectivity of the enzymes. PMID:18975918

  15. Streptococcus pneumoniae Phosphotyrosine Phosphatase CpsB and Alterations in Capsule Production Resulting from Changes in Oxygen Availability

    PubMed Central

    Geno, K. Aaron; Hauser, Jocelyn R.; Gupta, Kanupriya

    2014-01-01

    Streptococcus pneumoniae produces a protective capsular polysaccharide whose production must be modulated for bacterial survival within various host niches. Capsule production is affected in part by a phosphoregulatory system comprised of CpsB, CpsC, and CpsD. Here, we found that growth of serotype 2 strain D39 under conditions of increased oxygen availability resulted in decreased capsule levels concurrent with an ∼5-fold increase in Cps2B-mediated phosphatase activity. The change in Cps2B phosphatase activity did not result from alterations in the levels of either the cps2B transcript or the Cps2B protein. Recombinant Cps2B expressed in Escherichia coli similarly exhibited increased phosphatase activity under conditions of high-oxygen growth. S. pneumoniae D39 derivatives with defined deletion or point mutations in cps2B demonstrated reduced phosphatase activity with corresponding increases in levels of Cps2D tyrosine phosphorylation. There was, however, no correlation between these phenotypes and the level of capsule production. During growth under reduced-oxygen conditions, the Cps2B protein was essential for parental levels of capsule, but phosphatase activity alone could be eliminated without an effect on capsule. Under increased-oxygen conditions, deletion of cps2B did not affect capsule levels. These results indicate that neither Cps2B phosphatase activity nor Cps2D phosphorylation levels per se are determinants of capsule levels, whereas the Cps2B protein is important for capsule production during growth under conditions of reduced but not enhanced oxygen availability. Roles for factors outside the capsule locus, possible interactions between capsule regulatory proteins, and links to other cellular processes are also suggested by the results described in this study. PMID:24659769

  16. Defining Overweight and Obesity

    MedlinePlus

    ... Physical Activity Overweight & Obesity Healthy Weight Breastfeeding Micronutrient Malnutrition State and Local Programs Defining Adult Overweight and ... Physical Activity Overweight & Obesity Healthy Weight Breastfeeding Micronutrient Malnutrition State and Local Programs File Formats Help: How ...

  17. Interpolation and Definability

    NASA Astrophysics Data System (ADS)

    Gabbay, Dov M.; Maksimova, Larisa L.

    This chapter is on interpolation and definability. This notion is not only central in pure logic, but has significant meaning and applicability in all areas where logic itself is applied, especially in computer science, artificial intelligence, logic programming, philosophy of science and natural language. The notion may sometimes appear to the reader as too technical/mathematical but it does also have a general meaning in terms of expressibility and definability.

  18. The RCN1-encoded A subunit of protein phosphatase 2A increases phosphatase activity in vivo

    NASA Technical Reports Server (NTRS)

    Deruere, J.; Jackson, K.; Garbers, C.; Soll, D.; Delong, A.; Evans, M. L. (Principal Investigator)

    1999-01-01

    Protein phosphatase 2A (PP2A), a heterotrimeric serine/threonine-specific protein phosphatase, comprises a catalytic C subunit and two distinct regulatory subunits, A and B. The RCN1 gene encodes one of three A regulatory subunits in Arabidopsis thaliana. A T-DNA insertion mutation at this locus impairs root curling, seedling organ elongation and apical hypocotyl hook formation. We have used in vivo and in vitro assays to gauge the impact of the rcn1 mutation on PP2A activity in seedlings. PP2A activity is decreased in extracts from rcn1 mutant seedlings, and this decrease is not due to a reduction in catalytic subunit expression. Roots of mutant seedlings exhibit increased sensitivity to the phosphatase inhibitors okadaic acid and cantharidin in organ elongation assays. Shoots of dark-grown, but not light-grown seedlings also show increased inhibitor sensitivity. Furthermore, cantharidin treatment of wild-type seedlings mimics the rcn1 defect in root curling, root waving and hypocotyl hook formation assays. In roots of wild-type seedlings, RCN1 mRNA is expressed at high levels in root tips, and accumulates to lower levels in the pericycle and lateral root primordia. In shoots, RCN1 is expressed in the apical hook and the basal, rapidly elongating cells in etiolated hypocotyls, and in the shoot meristem and leaf primordia of light-grown seedlings. Our results show that the wild-type RCN1-encoded A subunit functions as a positive regulator of the PP2A holoenzyme, increasing activity towards substrates involved in organ elongation and differential cell elongation responses such as root curling.

  19. Structure and Mechanism of the Phosphotyrosyl Phosphatase Activator

    SciTech Connect

    Chao,Y.; Xing, Y.; Chen, Y.; Xu, Y.; Lin, Z.; Li, Z.; Jeffrey, P.; Stock, J.; Shi, Y.

    2006-01-01

    Phosphotyrosyl phosphatase activator (PTPA), also known as PP2A phosphatase activator, is a conserved protein from yeast to human. Here we report the 1.9 {angstrom} crystal structure of human PTPA, which reveals a previously unreported fold consisting of three subdomains: core, lid, and linker. Structural analysis uncovers a highly conserved surface patch, which borders the three subdomains, and an associated deep pocket located between the core and the linker subdomains. The conserved surface patch and the deep pocket are responsible for binding to PP2A and ATP, respectively. PTPA and PP2A A-C dimer together constitute a composite ATPase. PTPA binding to PP2A results in a dramatic alteration of substrate specificity, with enhanced phosphotyrosine phosphatase activity and decreased phosphoserine phosphatase activity. This function of PTPA strictly depends on the composite ATPase activity. These observations reveal significant insights into the function and mechanism of PTPA and have important ramifications for understanding PP2A function.

  20. Phosphatase activity of aerobic and facultative anaerobic bacteria.

    PubMed

    Pácová, Z; Kocur, M

    1978-10-01

    1115 strains of aerobic and facultatively anaerobic bacteria were tested for phosphatase activity by a conventional plate method and a microtest. The microtest was devised to allow results to be read after 4 h cultivation. Phosphatase activity was found in wide range of species and strains. Besides staphylococci, where the test for phosphatase is successfully used, it may be applied as one of the valuable tests for the differentiation of the following species: Bacillus cereus, B. licheniformis, Aeromonas spp., Vibrio parahaemolyticus, Actinobacillus spp., Pasteurella spp., Xanthomonas spp., Flavobacterium spp., Alteromonas putrefaciens, Pseudomonas maltophilia, Ps. cepacia, and some other species of Pseudomonas. The species which gave uniformly negative phosphatase reaction were as follows: Staph. saprophyticus, Acinetobacter calcoaceticus, Alcaligenes faecalis, and Bordetella bronchiseptica. PMID:216188

  1. Acid phosphatase and protease activities in immobilized rat skeletal muscles

    NASA Technical Reports Server (NTRS)

    Witzmann, F. A.; Troup, J. P.; Fitts, R. H.

    1982-01-01

    The effect of hind-limb immobilization on selected Iysosomal enzyme activities was studied in rat hing-limb muscles composed primarily of type 1. 2A, or 2B fibers. Following immobilization, acid protease and acid phosphatase both exhibited signifcant increases in their activity per unit weight in all three fiber types. Acid phosphatase activity increased at day 14 of immobilization in the three muscles and returned to control levels by day 21. Acid protease activity also changed biphasically, displaying a higher and earlier rise than acid phosphatase. The pattern of change in acid protease, but not acid phosphatase, closely parallels observed muscle wasting. The present data therefore demonstrate enhanced proteolytic capacity of all three fiber types early during muscular atrophy. In addition, the data suggest a dependence of basal hydrolytic and proteolytic activities and their adaptive response to immobilization on muscle fiber composition.

  2. 21 CFR 862.1050 - Alkaline phosphatase or isoenzymes test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Alkaline phosphatase or isoenzymes test system... Test Systems § 862.1050 Alkaline phosphatase or isoenzymes test system. (a) Identification. An alkaline phosphatase or isoenzymes test system is a device intended to measure alkaline phosphatase or its...

  3. 21 CFR 862.1050 - Alkaline phosphatase or isoenzymes test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Alkaline phosphatase or isoenzymes test system... Test Systems § 862.1050 Alkaline phosphatase or isoenzymes test system. (a) Identification. An alkaline phosphatase or isoenzymes test system is a device intended to measure alkaline phosphatase or its...

  4. Isolation and characterization of a neutral phosphatase from wheat seedlings

    SciTech Connect

    Cheng, H.F.

    1988-01-01

    A neutral phosphatase was purified to homogeneity from wheat seedlings. The enzyme was a monomeric glycoprotein exhibiting a molecular weight of 35,000, frictional ratio of 1.22, Stokes' radius of 26 A, and sedimentation coefficient of 3.2 S. That the enzyme was a glycoprotein was surmised from its chromatographic property on Concanavalin A-Sepharose column. The phosphatase activity was assayed using either fructose-2,6-bisphosphate or p-nitrophenyl phosphate as substrate. The phosphatase activity was not affected by high concentrations of chelating agents and did not require the addition of Mg{sup +2} or Ca{sup +2} for its activity. Molybdate, orthovanadate, Zn{sup +2}, and Hg{sup +2} were all potent inhibitors of the phosphatase activity. The inhibition by Hg{sup +2} was reversed by dithiothreitol. The enzyme activity was stimulated by Mn{sup +2} about 2-fold. On the other hand, 3-phosphoglycerate, fructose-6-P and Pi as well as polyamines inhibited the enzyme activity. The ability of the neutral phosphatase to dephosphorylate protein phosphotyrosine was also investigated. The phosphotyrosyl-substrates, such as ({sup 32}P) phosphotyrosyl-poly(Glu, Tyr)n, -alkylated bovine serum albumin, -angiotensin-1, and -band 3 of erythrocytes, were all substrates of the phosphatase. On the other hand, the enzyme had no activity toward protein phosphoserine and protein phosphothreonine.

  5. Unique carbohydrate binding platforms employed by the glucan phosphatases.

    PubMed

    Emanuelle, Shane; Brewer, M Kathryn; Meekins, David A; Gentry, Matthew S

    2016-07-01

    Glucan phosphatases are a family of enzymes that are functionally conserved at the enzymatic level in animals and plants. These enzymes bind and dephosphorylate glycogen in animals and starch in plants. While the enzymatic function is conserved, the glucan phosphatases employ distinct mechanisms to bind and dephosphorylate glycogen or starch. The founding member of the family is a bimodular human protein called laforin that is comprised of a carbohydrate binding module 20 (CBM20) followed by a dual specificity phosphatase domain. Plants contain two glucan phosphatases: Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2). SEX4 contains a chloroplast targeting peptide, dual specificity phosphatase (DSP) domain, a CBM45, and a carboxy-terminal motif. LSF2 is comprised of simply a chloroplast targeting peptide, DSP domain, and carboxy-terminal motif. SEX4 employs an integrated DSP-CBM glucan-binding platform to engage and dephosphorylate starch. LSF2 lacks a CBM and instead utilizes two surface binding sites to bind and dephosphorylate starch. Laforin is a dimeric protein in solution and it utilizes a tetramodular architecture and cooperativity to bind and dephosphorylate glycogen. This chapter describes the biological role of glucan phosphatases in glycogen and starch metabolism and compares and contrasts their ability to bind and dephosphorylate glucans. PMID:27147465

  6. A Bioassay for Lafora Disease and Laforin Glucan Phosphatase Activity

    PubMed Central

    Sherwood, Amanda R.; Johnson, Mary Beth; Delgado-Escueta, Antonio V.; Gentry, Matthew S.

    2013-01-01

    Objectives Lafora disease is a rare yet invariably fatal form of progressive neurodegenerative epilepsy resulting from mutations in the phosphatase laforin. Several therapeutic options for Lafora disease patients are currently being explored, and these therapies would benefit from a biochemical means of assessing functional laforin activity following treatment. To date, only clinical outcomes such as decreases in seizure frequency and severity have been used to indicate success of epilepsy treatment. However, these qualitative measures exhibit variability and must be assessed over long periods of time. In this work, we detail a simple and sensitive bioassay that can be used for the detection of functional endogenous laforin from human and mouse tissue. Design and methods We generated antibodies capable of detecting and immunoprecipitating endogenous laforin. Following laforin immunoprecipitation, laforin activity was assessed via phosphatase assays using para-nitrophenylphosphate (pNPP) and a malachite green-based assay specific for glucan phosphatase activity. Results We found that antibody binding to laforin does not impede laforin activity. Furthermore, the malachite green-based glucan phosphatase assay used in conjunction with a rabbit polyclonal laforin antibody was capable of detecting endogenous laforin activity from human and mouse tissue. Importantly, this assay discriminated between laforin activity and other phosphatases. Conclusions The bioassay that we have developed utilizing laforin antibodies and an assay specific for glucan phosphatase activity could prove valuable in the rapid detection of functional laforin in patients to which novel Lafora disease therapies have been administered. PMID:24012855

  7. Protein phosphatase 1 is a key player in nuclear events.

    PubMed

    Rebelo, Sandra; Santos, Mariana; Martins, Filipa; da Cruz e Silva, Edgar F; da Cruz e Silva, Odete A B

    2015-12-01

    Reversible protein phosphorylation at serine (Ser), threonine (Thr) and tyrosine (Tyr) residues is among the major regulatory mechanism in eukaryotic cells. The eukaryotic genome encodes many protein kinases and protein phosphatases. However, the localization, activity and specificity towards phosphatase substrates are dictated by a large array of phosphatase binding and regulatory subunits. For protein phosphatase 1 (PP1) more than 200 binding subunits have been described. The various PP1 isoforms and the binding subunits can be located throughout the cell, including in the nucleus. It follows that several nuclear specific PP1 binding proteins (PIPs) have been described and these will be discussed. Among them are PNUTS (phosphatase 1 nuclear targeting subunit), NIPP1 (nuclear inhibitor of PP1) and CREB (cAMP-responsive element-binding protein), which have all been associated with transcription. In fact PP1 can associate with transcription factors fulfilling an important regulatory function, in this respect it can bind to Hox11, human factor C1 (HCF1) and myocyte enhancer factor-2 (MEF2). PP1 also regulates cell cycle progression and centrosome maturation and splitting, again by binding to specific regulatory proteins. Moreover, PP1 together with other protein phosphatases control the entry into mitosis by regulating the activity of mitotic kinases. Thus, PP1, its binding proteins and/or the phosphorylation states of both, directly control a vast array of cell nucleus associated functions, many of which are starting to be unraveled. PMID:26275498

  8. Overexpression of Human Bone Alkaline Phosphatase in Pichia Pastoris

    NASA Technical Reports Server (NTRS)

    Karr, Laurel; Malone, Christine, C.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    The Pichiapastoris expression system was utilized to produce functionally active human bone alkaline phosphatase in gram quantities. Bone alkaline phosphatase is a key enzyme in bone formation and biomineralization, yet important questions about its structural chemistry and interactions with other cellular enzymes in mineralizing tissues remain unanswered. A soluble form of human bone alkaline phosphatase was constructed by deletion of the 25 amino acid hydrophobic C-terminal region of the encoding cDNA and inserted into the X-33 Pichiapastoris strain. An overexpression system was developed in shake flasks and converted to large-scale fermentation. Alkaline phosphatase was secreted into the medium to a level of 32mgAL when cultured in shake flasks. Enzyme activity was 12U/mg measured by a spectrophotometric assay. Fermentation yielded 880mgAL with enzymatic activity of 968U/mg. Gel electrophoresis analysis indicates that greater than 50% of the total protein in the fermentation is alkaline phosphatase. A purification scheme has been developed using ammonium sulfate precipitation followed by hydrophobic interaction chromatography. We are currently screening crystallization conditions of the purified recombinant protein for subsequent X-ray diffraction analyses. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

  9. Iron content and acid phosphatase activity in hepatic parenchymal lysosomes of patients with hemochromatosis before and after phlebotomy treatment

    SciTech Connect

    Cleton, M.I.; de Bruijn, W.C.; van Blokland, W.T.; Marx, J.J.; Roelofs, J.M.; Rademakers, L.H.

    1988-03-01

    Lysosomal structures in liver parenchymal cells of 3 patients with iron overload and of 3 subjects without iron-storage disorders were investigated. A combination of enzyme cytochemistry--with cerium as a captive ion to demonstrate lysosomal acid phosphatase activity--and electron probe X-ray microanalysis (EPMA) was used. We were able (1) to define and quantify lysosomal structures as lysosomes, siderosomes, or residual bodies, (2) to quantify the amount of iron and cerium simultaneously in these structures, and (3) to evaluate a possible relation between iron storage and enzyme activity. With histopathologically increased iron storage, the number of siderosomes had increased at the cost of lysosomes, with a corresponding increase in acid phosphatase activity in both organelles. In histopahtologically severe iron overload, however, acid phosphatase activity was low or not detectable and most of the iron was stored in residual bodies. After phlebotomy treatment, the number of siderosomes had decreased in favor of the lysosomes, approaching values obtained in control subjects, and acid phosphatase activity was present in all iron-containing structures. In this way a relationship between iron storage and enzyme activity was established. The iron content of the individual lysosomal structures per unit area had increased with histopathologically increased iron storage and had decreased after phlebotomy treatment. From this observation, it is concluded that the iron status of the patient is not only reflected by the amount of iron-containing hepatocytes but, as well, by the iron content lysosomal unit area.

  10. [Phosphatase activity in Amoeba proteus at pH 9.0].

    PubMed

    Sopina, V A

    2007-01-01

    In the free-living amoeba Amoeba proteus (strain B), after PAAG disk-electrophoresis of the homogenate supernatant, at using 1-naphthyl phosphate as a substrate and pH 9.0, three forms of phosphatase activity were revealed; they were arbitrarily called "fast", "intermediate", and "slow" phosphatases. The fast phosphatase has been established to be a fraction of lysosomal acid phosphatase that preserves some low activity at alkaline pH. The question as to which particular class the intermediate phosphatase belongs to has remained unanswered: it can be both acid phosphatase and protein tyrosine phosphatase (PTP). Based on data of inhibitor analysis, large substrate specificity, results of experiments with reactivation by Zn ions after inactivation with EDTA, other than in the fast and intermediate phosphatases localization in the amoeba cell, it is concluded that only slow phosphatase can be classified as alkaline phosphatase (EC 3.1.3.1). PMID:17933343

  11. Defining Airflow Obstruction

    PubMed Central

    Eschenbacher, William L.

    2016-01-01

    Airflow obstruction has been defined using spirometric test results when the forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) ratio is below a fixed cutoff (<70%) or lower limits of normal (LLN) from reference equations that are based on values from a normal population. However, similar to other positive or abnormal diagnostic test results that are used to identify the presence of disease, perhaps airflow obstruction should be defined based on the values of FEV1/FVC for a population of individuals with known disease such as chronic obstructive pulmonary disease (COPD). Unfortunately, we do not know such a distribution of values of FEV1/FVC for patients with COPD since there is no gold standard for this syndrome or condition. Yet, we have used this physiologic definition of airflow obstruction based on a normal population to identify patients with COPD. In addition, we have defined airflow obstruction as either being present or absent. Instead, we should use a different approach to define airflow obstruction based on the probability or likelihood that the airflow obstruction is present which in turn would give us the probability or likelihood of a disease state such as COPD. PMID:27239557

  12. Defining Equality in Education

    ERIC Educational Resources Information Center

    Benson, Ronald E.

    1977-01-01

    Defines equality of education in three areas: 1) by the degree of integration of school systems; 2) by a comparison of material resources and assets in education; and 3) by the effects of schooling as measured by the mean scores of groups on standardized tests. Available from: College of Education, 107 Quadrangle, Iowa State University, Ames, Iowa…

  13. Defining Supports Geometry

    ERIC Educational Resources Information Center

    Stephan, Michelle L.; McManus, George E.; Dickey, Ashley L.; Arb, Maxwell S.

    2012-01-01

    The process of developing definitions is underemphasized in most mathematics instruction. Investing time in constructing meaning is well worth the return in terms of the knowledge it imparts. In this article, the authors present a third approach to "defining," called "constructive." It involves modifying students' previous understanding of a term…

  14. On Defining Mass

    ERIC Educational Resources Information Center

    Hecht, Eugene

    2011-01-01

    Though central to any pedagogical development of physics, the concept of mass is still not well understood. Properly defining mass has proven to be far more daunting than contemporary textbooks would have us believe. And yet today the origin of mass is one of the most aggressively pursued areas of research in all of physics. Much of the excitement…

  15. Defining Effective Teaching

    ERIC Educational Resources Information Center

    Layne, L.

    2012-01-01

    The author looks at the meaning of specific terminology commonly used in student surveys: "effective teaching." The research seeks to determine if there is a difference in how "effective teaching" is defined by those taking student surveys and those interpreting the results. To investigate this difference, a sample group of professors and students…

  16. Defining structural limit zones

    NASA Technical Reports Server (NTRS)

    Merchant, D. H.

    1978-01-01

    Method for defining limit loads uses probability distribution of largest load occurring during given time intervals. Method is compatible with both deterministic and probabilistic structural design criteria. It also rationally accounts for fact that longer structure is exposed to random loading environment, greater is possibility that it will experience extreme load.

  17. Defining Faculty Work.

    ERIC Educational Resources Information Center

    Gray, Peter J.; Diamond, Robert M.

    1994-01-01

    A process of planned change is proposed for redefining college faculty work. Legitimate faculty work is defined in broad terms, and information sources and methods for collecting information to support redefinition are identified. The final step in the redefinition process is the development of new mission statements for the institution and its…

  18. Defined by Limitations

    ERIC Educational Resources Information Center

    Arriola, Sonya; Murphy, Katy

    2010-01-01

    Undocumented students are a population defined by limitations. Their lack of legal residency and any supporting paperwork (e.g., Social Security number, government issued identification) renders them essentially invisible to the American and state governments. They cannot legally work. In many states, they cannot legally drive. After the age of…

  19. Protein phosphatase 1α is a Ras-activated Bad phosphatase that regulates interleukin-2 deprivation-induced apoptosis

    PubMed Central

    Ayllón, Verónica; Martínez-A, Carlos; García, Alphonse; Cayla, Xavier; Rebollo, Angelita

    2000-01-01

    Growth factor deprivation is a physiological mechanism to regulate cell death. We utilize an interleukin-2 (IL-2)-dependent murine T-cell line to identify proteins that interact with Bad upon IL-2 stimulation or deprivation. Using the yeast two-hybrid system, glutathione S-transferase (GST) fusion proteins and co-immunoprecipitation techniques, we found that Bad interacts with protein phosphatase 1α (PP1α). Serine phosphorylation of Bad is induced by IL-2 and its dephosphorylation correlates with appearance of apoptosis. IL-2 deprivation induces Bad dephosphorylation, suggesting the involvement of a serine phosphatase. A serine/threonine phosphatase activity, sensitive to the phosphatase inhibitor okadaic acid, was detected in Bad immunoprecipitates from IL-2-stimulated cells, increasing after IL-2 deprivation. This enzymatic activity also dephosphorylates in vivo 32P-labeled Bad. Treatment of cells with okadaic acid blocks Bad dephosphorylation and prevents cell death. Finally, Ras activation controls the catalytic activity of PP1α. These results strongly suggest that Bad is an in vitro and in vivo substrate for PP1α phosphatase and that IL-2 deprivation-induced apoptosis may operate by regulating Bad phosphorylation through PP1α phosphatase, whose enzymatic activity is regulated by Ras. PMID:10811615

  20. The receptor protein tyrosine phosphatase LAR promotes R7 photoreceptor axon targeting by a phosphatase-independent signaling mechanism

    PubMed Central

    Hofmeyer, Kerstin; Treisman, Jessica E.

    2009-01-01

    Receptor protein tyrosine phosphatases (RPTPs) control many aspects of nervous system development. At the Drosophila neuromuscular junction (NMJ), regulation of synapse growth and maturation by the RPTP LAR depends on catalytic phosphatase activity and on the extracellular ligands Syndecan and Dally-like. We show here that the function of LAR in controlling R7 photoreceptor axon targeting in the visual system differs in several respects. The extracellular domain of LAR important for this process is distinct from the domains known to bind Syndecan and Dally-like, suggesting the involvement of a different ligand. R7 targeting does not require LAR phosphatase activity, but instead depends on the phosphatase activity of another RPTP, PTP69D. In addition, a mutation that prevents dimerization of the intracellular domain of LAR interferes with its ability to promote R7 targeting, although it does not disrupt phosphatase activity or neuromuscular synapse growth. We propose that LAR function in R7 is independent of its phosphatase activity, but requires structural features that allow dimerization and may promote the assembly of downstream effectors. PMID:19889974

  1. Defining Dynamic Route Structure

    NASA Technical Reports Server (NTRS)

    Zelinski, Shannon; Jastrzebski, Michael

    2011-01-01

    This poster describes a method for defining route structure from flight tracks. Dynamically generated route structures could be useful in guiding dynamic airspace configuration and helping controllers retain situational awareness under dynamically changing traffic conditions. Individual merge and diverge intersections between pairs of flights are identified, clustered, and grouped into nodes of a route structure network. Links are placed between nodes to represent major traffic flows. A parametric analysis determined the algorithm input parameters producing route structures of current day flight plans that are closest to todays airway structure. These parameters are then used to define and analyze the dynamic route structure over the course of a day for current day flight paths. Route structures are also compared between current day flight paths and more user preferred paths such as great circle and weather avoidance routing.

  2. Defining the paramedic process.

    PubMed

    Carter, Holly; Thompson, James

    2015-01-01

    The use of a 'process of care' is well established in several health professions, most evidently within the field of nursing. Now ingrained within methods of care delivery, it offers a logical approach to problem solving and ensures an appropriate delivery of interventions that are specifically suited to the individual patient. Paramedicine is a rapidly advancing profession despite a wide acknowledgement of limited research provisions. This frequently results in the borrowing of evidence from other disciplines. While this has often been useful, there are many concerns relating to the acceptable limit of evidence transcription between professions. To date, there is no formally recognised 'process of care'-defining activity within the pre-hospital arena. With much current focus on the professional classification of paramedic work, it is considered timely to formally define a formula that underpins other professional roles such as nursing. It is hypothesised that defined processes of care, particularly the nursing process, may have features that would readily translate to pre-hospital practice. The literature analysed was obtained through systematic searches of a range of databases, including Ovid MEDLINE, Cumulative Index to Nursing and Allied Health. The results demonstrated that the defined process of care provides nursing with more than just a structure for practice, but also has implications for education, clinical governance and professional standing. The current nursing process does not directly articulate to the complex and often unstructured role of the paramedic; however, it has many principles that offer value to the paramedic in their practice. Expanding the nursing process model to include the stages of Dispatch Considerations, Scene Assessment, First Impressions, Patient History, Physical Examination, Clinical Decision-Making, Interventions, Re-evaluation, Transport Decisions, Handover and Reflection would provide an appropriate model for pre

  3. Glycerol-3-phosphatase of Corynebacterium glutamicum.

    PubMed

    Lindner, Steffen N; Meiswinkel, Tobias M; Panhorst, Maren; Youn, Jung-Won; Wiefel, Lars; Wendisch, Volker F

    2012-06-15

    Formation of glycerol as by-product of amino acid production by Corynebacterium glutamicum has been observed under certain conditions, but the enzyme(s) involved in its synthesis from glycerol-3-phosphate were not known. It was shown here that cg1700 encodes an enzyme active as a glycerol-3-phosphatase (GPP) hydrolyzing glycerol-3-phosphate to inorganic phosphate and glycerol. GPP was found to be active as a homodimer. The enzyme preferred conditions of neutral pH and requires Mg²⁺ or Mn²⁺ for its activity. GPP dephosphorylated both L- and D-glycerol-3-phosphate with a preference for the D-enantiomer. The maximal activity of GPP was estimated to be 31.1 and 1.7 U mg⁻¹ with K(M) values of 3.8 and 2.9 mM for DL- and L-glycerol-3-phosphate, respectively. For physiological analysis a gpp deletion mutant was constructed and shown to lack the ability to produce detectable glycerol concentrations. Vice versa, gpp overexpression increased glycerol accumulation during growth in fructose minimal medium. It has been demonstrated previously that intracellular accumulation of glycerol-3-phosphate is growth inhibitory as shown for a recombinant C. glutamicum strain overproducing glycerokinase and glycerol facilitator genes from E. coli in media containing glycerol. In this strain, overexpression of gpp restored growth in the presence of glycerol as intracellular glycerol-3-phosphate concentrations were reduced to wild-type levels. In C. glutamicum wild type, GPP was shown to be involved in utilization of DL-glycerol-3-phosphate as source of phosphorus, since growth with DL-glycerol-3-phosphate as sole phosphorus source was reduced in the gpp deletion strain whereas it was accelerated upon gpp overexpression. As GPP homologues were found to be encoded in the genomes of many other bacteria, the gpp homologues of Escherichia coli (b2293) and Bacillus subtilis (BSU09240, BSU34970) as well as gpp1 from the plant Arabidosis thaliana were overexpressed in E. coli MG1655 and

  4. Human prostatic acid phosphatase directly stimulates collagen synthesis and alkaline phosphatase content of isolated bone cells

    SciTech Connect

    Ishibe, M.; Rosier, R.N.; Puzas, J.E. )

    1991-10-01

    Human prostatic acid phosphatase (hPAP) directly enhances the differentiated characteristics of isolated bone cells in vitro. This enzyme, when added to cell cultures for 24 h in vitro stimulates collagen synthesis and the production of alkaline phosphatase. The effects are dose dependent, with statistically significant effects occurring from 0.1-100 nM hPAP. Concentrations higher than 100 nM do not evoke greater effects. The maximal effect of hPAP occurs between 12 and 24 h of exposure. The cells stimulated to the greatest degree are osteoprogenitor cells and osteoblasts. Fibroblasts isolated from the same tissue show a lesser sensitivity to hPAP. hPAP has no detectable effect on cell proliferation, as measured by radiolabeled thymidine incorporation or total DNA synthesis. None of the observations reported in this work can be attributed to contaminating proteins in the hPAP preparation. hPAP was radiolabeled with 125I and was used for affinity binding and cross-linking studies. Scatchard analysis of specific binding indicated the presence of 1.0 X 10(5) high affinity binding sites/cell, with a Kd of 6.5 nM. Cross-linking studies demonstrated the presence of one 320-kDa binding complex. The pH profile and kinetic determinations of Km and maximum velocity for hPAP were similar to those previously reported, except for the finding of positive cooperativity of the substrate with the enzyme under the conditions of our assay. We believe that the direct stimulation of bone-forming cells by hPAP may contribute to the sclerotic nature of skeletal bone around sites of neoplastic prostatic metastases and that the effect of the enzyme is probably mediated by a plasma membrane receptor.

  5. Protein phosphatase 2A regulatory subunit B56α limits phosphatase activity in the heart.

    PubMed

    Little, Sean C; Curran, Jerry; Makara, Michael A; Kline, Crystal F; Ho, Hsiang-Ting; Xu, Zhaobin; Wu, Xiangqiong; Polina, Iuliia; Musa, Hassan; Meadows, Allison M; Carnes, Cynthia A; Biesiadecki, Brandon J; Davis, Jonathan P; Weisleder, Noah; Györke, Sandor; Wehrens, Xander H; Hund, Thomas J; Mohler, Peter J

    2015-07-21

    Protein phosphatase 2A (PP2A) is a serine/threonine-selective holoenzyme composed of a catalytic, scaffolding, and regulatory subunit. In the heart, PP2A activity is requisite for cardiac excitation-contraction coupling and central in adrenergic signaling. We found that mice deficient in the PP2A regulatory subunit B56α (1 of 13 regulatory subunits) had altered PP2A signaling in the heart that was associated with changes in cardiac physiology, suggesting that the B56α regulatory subunit had an autoinhibitory role that suppressed excess PP2A activity. The increase in PP2A activity in the mice with reduced B56α expression resulted in slower heart rates and increased heart rate variability, conduction defects, and increased sensitivity of heart rate to parasympathetic agonists. Increased PP2A activity in B56α(+/-) myocytes resulted in reduced Ca(2+) waves and sparks, which was associated with decreased phosphorylation (and thus decreased activation) of the ryanodine receptor RyR2, an ion channel on intracellular membranes that is involved in Ca(2+) regulation in cardiomyocytes. In line with an autoinhibitory role for B56α, in vivo expression of B56α in the absence of altered abundance of other PP2A subunits decreased basal phosphatase activity. Consequently, in vivo expression of B56α suppressed parasympathetic regulation of heart rate and increased RyR2 phosphorylation in cardiomyocytes. These data show that an integral component of the PP2A holoenzyme has an important inhibitory role in controlling PP2A enzyme activity in the heart. PMID:26198358

  6. Characterization of Human Bone Alkaline Phosphatase in Pichia Pastoris

    NASA Technical Reports Server (NTRS)

    Malone, Christine C.; Ciszak, Eva; Karr, Laurel J.

    1999-01-01

    A soluble form of human bone alkaline phosphatase has been expressed in a recombinant strain of the methylotrophic yeast Pichia pastoris. We constructed a plasmid containing cDNA encoding for human bone alkaline phosphatase, with the hydrophobic carboxyl terminal portion deleted. Alkaline phosphatase was secreted into the medium to a level of 32mg/L when cultured in shake flasks, and enzyme activity was 12U/mg, as measured by a spectrophotometric assay. By conversion to a fermentation system, a yield of 880mg/L has been achieved with an enzyme activity of 968U/mg. By gel electrophoresis analysis, it appears that greater than 50% of the total protein in the fermentation media is alkaline phosphatase. Although purification procedures are not yet completely optimized, they are expected to include filtration, ion exchange and affinity chromatography. Our presentation will focus on the purification and crystallization results up to the time of the conference. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

  7. New Functions of the Inositol Polyphosphate 5-Phosphatases in Cancer.

    PubMed

    Erneux, Christophe; Ghosh, Somadri; Ramos, Ana Raquel; Edimo, William's Elong

    2016-01-01

    Inositol polyphosphate 5-phosphatases act on inositol phosphates and phosphoinositides as substrates. They are 10 different isoenzymes and several splice variants in the human genome that are involved in a series of human pathologies such as the Lowe syndrome, the Joubert and MORM syndromes, breast cancer, glioblastoma, gastric cancer and several other type of cancers. Inositol 5-phosphatases can be amplified in human cancer cells, whereas the 3- and 4- phosphatase tumor suppressor PTEN and INPP4B, repectively are often repressed or deleted. The inositol 5-phosphatases are critically involved in a complex network of higly regulated phosphoinositides, affecting the lipid content of PI(3, 4, 5)P3, PI(4, 5)P2 and PI(3, 4)P2. This has an impact on the normal behavior of many intracellular target proteins e.g. protein kinase B (PKB/Akt) or actin binding proteins and final biological responses. The production of PI(3, 4P)2 by dephosphorylation of the substrate PI(3, 4, 5)P3 is particularly important as it produces a new signal messenger in the control of cell migration, invasion and endocytosis. New inhibitors/activators of inositol 5- phosphatases have recently been identified for the possible control of their activity in several human pathologies such as inflamation and cancer. PMID:26916021

  8. Defining functional dyspepsia.

    PubMed

    Mearin, Fermín; Calleja, José Luis

    2011-12-01

    Dyspepsia and functional dyspepsia represent a highly significant public health issue. A good definition of dyspepsia is key for helping us to better approach symptoms, decision making, and therapy indications.During the last few years many attempts were made at establishing a definition of dyspepsia. Results were little successful on most occasions, and clear discrepancies arose on whether symptoms should be associated with digestion, which types of symptoms were to be included, which anatomic location should symptoms have, etc.The Rome III Committee defined dyspepsia as "a symptom or set of symptoms that most physicians consider to originate from the gastroduodenal area", including the following: postprandial heaviness, early satiety, and epigastric pain or burning. Two new entities were defined: a) food-induced dyspeptic symptoms (postprandial distress syndrome); and b) epigastric pain (epigastric pain syndrome). These and other definitions have shown both strengths and weaknesses. At times they have been much too complex, at times much too simple; furthermore, they have commonly erred on the side of being inaccurate and impractical. On the other hand, some (the most recent ones) are difficult to translate into the Spanish language. In a meeting of gastroenterologists with a special interest in digestive functional disorders, the various aspects of dyspepsia definition were discussed and put to the vote, and the following conclusions were arrived at: dyspepsia is defined as a set of symptoms, either related or unrelated to food ingestion, localized on the upper half of the abdomen. They include: a) epigastric discomfort (as a category of severity) or pain; b) postprandial heaviness; and c) early satiety. Associated complaints include: nausea, belching, bloating, and epigastric burn (heartburn). All these must be scored according to severity and frequency. Furthermore, psychological factors may be involved in the origin of functional dyspepsia. On the other hand

  9. Defining periodontal health

    PubMed Central

    2015-01-01

    Assessment of the periodontium has relied exclusively on a variety of physical measurements (e.g., attachment level, probing depth, bone loss, mobility, recession, degree of inflammation, etc.) in relation to various case definitions of periodontal disease. Periodontal health was often an afterthought and was simply defined as the absence of the signs and symptoms of a periodontal disease. Accordingly, these strict and sometimes disparate definitions of periodontal disease have resulted in an idealistic requirement of a pristine periodontium for periodontal health, which makes us all diseased in one way or another. Furthermore, the consequence of not having a realistic definition of health has resulted in potentially questionable recommendations. The aim of this manuscript was to assess the biological, environmental, sociological, economic, educational and psychological relationships that are germane to constructing a paradigm that defines periodontal health using a modified wellness model. The paradigm includes four cardinal characteristics, i.e., 1) a functional dentition, 2) the painless function of a dentition, 3) the stability of the periodontal attachment apparatus, and 4) the psychological and social well-being of the individual. Finally, strategies and policies that advocate periodontal health were appraised. I'm not sick but I'm not well, and it's a sin to live so well. Flagpole Sitta, Harvey Danger PMID:26390888

  10. [Interaction of two tumor suppressors: Phosphatase CTDSPL and Rb protein].

    PubMed

    Beniaminov, A D; Krasnov, G S; Dmitriev, A A; Puzanov, G A; Snopok, B A; Senchenko, V N; Kashuba, V I

    2016-01-01

    Earlier we established that CTDSPL gene encoding small carboxy-terminal domain serine phosphatase can be considered a classical tumor suppressor gene. Besides, transfection of tumor cell line MCF-7 with CTDSPL led to the content decrease of inactive phosphorylated form of another tumor suppressor, retinoblastoma protein (Rb), and subsequently to cell cycle arrest at the G1/S boundary. This result implied that small phosphatase CTDSPL is able to specifically dephosphorylate and activate Rb protein. In order to add some fuel to this hypothesis, in the present work we studied the interaction of two tumor suppressors CTDSPL and Rb in vitro. GST pool-down assay revealed that CTDSPL is able to precipitate Rb protein from MCF-7 cell extracts, while surface plasmon resonance technique showed that interaction of the two proteins is direct. Results of this study reassert that phosphatase CTDSPL and Rb could be involved in the common mechanism of cell cycle regulation. PMID:27414789

  11. Characterization of the PEST family protein tyrosine phosphatase BDP1.

    PubMed

    Kim, Y W; Wang, H; Sures, I; Lammers, R; Martell, K J; Ullrich, A

    1996-11-21

    Using a polymerase chain reaction (PCR) amplification strategy, we identified a novel protein tyrosine phosphatase (PTPase) designated Brain Derived Phosphatase (BDP1). The full length sequence encoded an open reading frame of 459 amino acids with no transmembrane domain and had a calculated molecular weight of 50 kDa. The predicted amino acid sequence contained a PEST motif and accordingly, BDP1 shared the greatest homology with members of the PTP-PEST family. When transiently expressed in 293 cells BDP1 hydrolyzed p-Nitrophenylphosphate, confirming it as a functional protein tyrosine phosphatase. Northern blot analysis indicated that BDP1 was expressed not only in brain, but also in colon and several different tumor-derived cell lines. Furthermore, BDP1 was found to differentially dephosphorylate autophosphorylated tyrosine kinases which are known to be overexpressed in tumor tissues. PMID:8950995

  12. Applying a Targeted Label-free Approach using LC-MS AMT Tags to Evaluate Changes in Protein Phosphorylation Following Phosphatase Inhibition

    SciTech Connect

    Yang, Feng; Jaitly, Navdeep; Jayachandran, Hemalatha; Lou, Quanzhou; Monroe, Matthew E.; Du, Xiuxia; Gritsenko, Marina A.; Zhang, Rui; Anderson, David J.; Purvine, Samuel O.; Adkins, Joshua N.; Moore, Ronald J.; Mottaz, Heather M.; Ding, Shi-Jian; Lipton, Mary S.; Camp, David G.; Udseth, Harold R.; Smith, Richard D.; Rossie, Sandra S.

    2007-10-12

    To identify phosphoproteins regulated by the phosphoprotein phosphatase (PPP) family of S/T phosphatases, we performed a large-scale characterization of changes in protein phosphorylation on extracts from HeLa cells treated with or without calyculin A, a potent PPP enzyme inhibitor. A label-free comparative Phosphoproteomics approach using immobilized metal ion affinity chromatography and targeted tandem mass spectrometry was employed to discover and identify signatures based upon distinctive changes in abundance. Overall, 232 proteins were identified as either direct or indirect targets for PPP enzyme regulation. Most of the present identifications represent novel PPP enzyme targets at the level of both phosphorylation site and protein. These include phosphorylation sites within signaling proteins such as p120 Catenin, A Kinase Anchoring Protein 8, JunB, and Type II Phosphatidyl Inositol 4 Kinase. These data can be used to define underlying signaling pathways and events regulated by the PPP family of S/T phosphatases.

  13. Structural Basis of Response Regulator Dephosphorylation by Rap Phosphatases

    SciTech Connect

    V Parashar; N Mirouze; D Dubnau; M Neiditch

    2011-12-31

    Bacterial Rap family proteins have been most extensively studied in Bacillus subtilis, where they regulate activities including sporulation, genetic competence, antibiotic expression, and the movement of the ICEBs1 transposon. One subset of Rap proteins consists of phosphatases that control B. subtilis and B. anthracis sporulation by dephosphorylating the response regulator Spo0F. The mechanistic basis of Rap phosphatase activity was unknown. Here we present the RapH-Spo0F X-ray crystal structure, which shows that Rap proteins consist of a 3-helix bundle and a tetratricopeptide repeat domain. Extensive biochemical and genetic functional studies reveal the importance of the observed RapH-Spo0F interactions, including the catalytic role of a glutamine in the RapH 3-helix bundle that inserts into the Spo0F active site. We show that in addition to dephosphorylating Spo0F, RapH can antagonize sporulation by sterically blocking phosphoryl transfer to and from Spo0F. Our structure-function analysis of the RapH-Spo0F interaction identified Rap protein residues critical for Spo0F phosphatase activity. This information enabled us to assign Spo0F phosphatase activity to a Rap protein based on sequence alone, which was not previously possible. Finally, as the ultimate test of our newfound understanding of the structural requirements for Rap phosphatase function, a non-phosphatase Rap protein that inhibits the binding of the response regulator ComA to DNA was rationally engineered to dephosphorylate Spo0F. In addition to revealing the mechanistic basis of response regulator dephosphorylation by Rap proteins, our studies support the previously proposed T-loop-Y allostery model of receiver domain regulation that restricts the aromatic 'switch' residue to an internal position when the {beta}4-{alpha}4 loop adopts an active-site proximal conformation.

  14. TAPERED DEFINING SLOT

    DOEpatents

    Pressey, F.W.

    1959-09-01

    An improvement is reported in the shape and formation of the slot or opening in the collimating slot member which forms part of an ion source of the type wherein a vapor of the material to be ionized is bombarded by electrons in a magnetic field to strike an arc-producing ionization. The defining slot is formed so as to have a substantial taper away from the cathode, causing the electron bombardment from the cathode to be dispersed over a greater area reducing its temperature and at the same time bringing the principal concentration of heat from the electron bombardment nearer the anode side of the slot, thus reducing deterioration and prolonging the life of the slot member during operation.

  15. SHP-2 phosphatase activity is required for PECAM-1-dependent cell motility.

    PubMed

    Zhu, Jing-Xu; Cao, Gaoyuan; Williams, James T; Delisser, Horace M

    2010-10-01

    Platelet endothelial cell adhesion molecule-1 (PECAM-1) has been implicated in endothelial cell motility during angiogenesis. Although there is evidence that SHP-2 plays a role in PECAM-1-dependent cell motility, the molecular basis of the activity of SHP-2 in this process has not been defined. To investigate the requirement of SHP-2 in PECAM-1-dependent cell motility, studies were done in which various constructs of SHP-2 were expressed in cell transfectants expressing PECAM-1. We observed that the levels of PECAM-1 tyrosine phosphorylation and SHP-2 association with PECAM-1 were significantly increased in cells expressing a phosphatase-inactive SHP-2 mutant, suggesting that the level of PECAM-1 tyrosine phosphorylation, and thus SHP-2 binding are regulated in part by bound, catalytically active SHP-2. We subsequently found that expression of PECAM-1 stimulated wound-induced migration and the formation of filopodia (a morphological feature of motile cells). These activities were associated with increased mitogen-activated protein kinase (MAPK) activation and the dephosphorylation of paxillin (an event implicated in the activation of MAPK). The phosphatase-inactive SHP-2 mutant, however, suppressed these PECAM-1-dependent phenomena, whereas the activity of PECAM-1 expressing cells was not altered by expression of wild-type SHP-2 or SHP-2 in which the scaffold/adaptor function had been disabled. Pharmacological inhibition of SHP-2 phosphatase activity also suppressed PECAM-1-dependent motility. Furthermore, PECAM-1 expression also stimulates tube formation, but none of the SHP-2 constructs affected this process. These findings therefore suggest a model for the involvement of SHP-2 in PECAM-1-dependent motility in which SHP-2, recruited by its interaction with PECAM-1, targets paxillin to ultimately activate the MAPK pathway and downstream events required for cell motility. PMID:20631249

  16. Counter-regulatory phosphatases TNAP and NPP1 temporally regulate tooth root cementogenesis.

    PubMed

    Zweifler, Laura E; Patel, Mudita K; Nociti, Francisco H; Wimer, Helen F; Millán, Jose L; Somerman, Martha J; Foster, Brian L

    2015-03-01

    Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate (Pi) to mineral inhibitor pyrophosphate (PPi), where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase (TNAP) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enpp1 null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enpp1 gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected. PMID:25504209

  17. Bacterial Expression and HTS Assessment of Soluble Epoxide Hydrolase Phosphatase.

    PubMed

    Klingler, Franca-Maria; Wolf, Markus; Wittmann, Sandra; Gribbon, Philip; Proschak, Ewgenij

    2016-08-01

    Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that possesses an epoxide hydrolase and lipid phosphatase activity (sEH-P) at two distinct catalytic domains. While the physiological role of the epoxide hydrolase domain is well understood, the consequences of the phosphatase activity remain unclear. Herein we describe the bacterial expression of the recombinant N-terminal domain of sEH-P and the development of a high-throughput screening protocol using a sensitive and commercially available substrate fluorescein diphosphate. The usability of the assay system was demonstrated and novel inhibitors of sEH-P were identified. PMID:27009944

  18. Genetic alterations of protein tyrosine phosphatases in human cancers

    PubMed Central

    Zhao, Shuliang; Sedwick, David; Wang, Zhenghe

    2014-01-01

    Protein tyrosine phosphatases (PTPs) are enzymes that remove phosphate from tyrosine residues in proteins. Recent whole-exome sequencing of human cancer genomes reveals that many PTPs are frequently mutated in a variety of cancers. Among these mutated PTPs, protein tyrosine phosphatase T (PTPRT) appears to be the most frequently mutated PTP in human cancers. Beside PTPN11 which functions as an oncogene in leukemia, genetic and functional studies indicate that most of mutant PTPs are tumor suppressor genes. Identification of the substrates and corresponding kinases of the mutant PTPs may provide novel therapeutic targets for cancers harboring these mutant PTPs. PMID:25263441

  19. Characterization of the CTD phosphatase Fcp1 from fission yeast. Preferential dephosphorylation of serine 2 versus serine 5.

    PubMed

    Hausmann, Stéphane; Shuman, Stewart

    2002-06-14

    The C-terminal domain (CTD) of RNA polymerase II undergoes extensive phosphorylation and dephosphorylation at positions Ser2 and Ser5 during the transcription cycle. A single CTD phosphatase, Fcp1, has been identified in yeast and metazoans. Here we conducted a biochemical characterization of Fcp1 from the fission yeast Schizosaccharomyces pombe. The 723-amino acid Fcp1 protein was expressed at high levels in bacteria. Recombinant Fcp1 catalyzed the metal-dependent hydrolysis of para-nitrophenyl phosphate with a pH optimum of 5.5 (kcat = 2 s(-1); K(m) = 19 mm). Deletion analysis showed that 139- and 143-amino acid segments could be deleted from the N and C termini of Fcp1, respectively, without affecting phosphatase activity. A segment containing amino acids 487-580, deletion of which abolished activity, embraces a BRCT domain present in all known Fcp1 orthologs. Mutations of residues Asp170 and Asp172 abrogated Fcp1 phosphatase activity; the essential aspartates are located within a 170DXDXT172 motif that defines a superfamily of metal-dependent phosphotransferases. We exploited defined synthetic CTD phosphopeptide substrates to show for the first time that: (i) Fcp1 CTD phosphatase activity is not confined to native polymerase II and (ii) Fcp1 displays an inherent preference for a particular CTD phosphorylation array. Using equivalent concentrations (25 microm) of CTD peptides of identical amino acid sequence and phosphoserine content, which differed only in the positions of phosphoserine within the heptad, we found that Fcp1 was 10-fold more active in dephosphorylating Ser2-PO4 than Ser5-PO4. PMID:11934898

  20. Defining the Anthropocene

    NASA Astrophysics Data System (ADS)

    Lewis, Simon; Maslin, Mark

    2016-04-01

    Time is divided by geologists according to marked shifts in Earth's state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Should the Anthropocene - the idea that human activity is a force acting upon the Earth system in ways that mean that Earth will be altered for millions of years - be defined as a geological time-unit at the level of an Epoch? Here we appraise the data to assess such claims, first in terms of changes to the Earth system, with particular focus on very long-lived impacts, as Epochs typically last millions of years. Can Earth really be said to be in transition from one state to another? Secondly, we then consider the formal criteria used to define geological time-units and move forward through time examining whether currently available evidence passes typical geological time-unit evidence thresholds. We suggest two time periods likely fit the criteria (1) the aftermath of the interlinking of the Old and New Worlds, which moved species across continents and ocean basins worldwide, a geologically unprecedented and permanent change, which is also the globally synchronous coolest part of the Little Ice Age (in Earth system terms), and the beginning of global trade and a new socio-economic "world system" (in historical terms), marked as a golden spike by a temporary drop in atmospheric CO2, centred on 1610 CE; and (2) the aftermath of the Second World War, when many global environmental changes accelerated and novel long-lived materials were increasingly manufactured, known as the Great Acceleration (in Earth system terms) and the beginning of the Cold War (in historical terms), marked as a golden spike by the peak in radionuclide fallout in 1964. We finish by noting that the Anthropocene debate is politically loaded, thus transparency in the presentation of evidence is essential if a formal definition of the Anthropocene is to avoid becoming a debate about bias. The

  1. Associations between Renal Hyperfiltration and Serum Alkaline Phosphatase

    PubMed Central

    Oh, Se Won; Han, Kum Hyun; Han, Sang Youb

    2015-01-01

    Renal hyperfiltration, which is associated with renal injury, occurs in diabetic or obese individuals. Serum alkaline phosphatase (ALP) level is also elevated in patients with diabetes (DM) or metabolic syndrome (MS), and increased urinary excretion of ALP has been demonstrated in patients who have hyperfiltration and tubular damage. However, little was investigated about the association between hyperfiltration and serum ALP level. A retrospective observational study of the 21,308 adults in the Korea National Health and Nutrition Examination Survey IV-V databases (2008–2011) was performed. Renal hyperfiltration was defined as exceeding the age- and sex-specific 97.5th percentile. We divided participants into 4 groups according to their estimated glomerular filtration rate (eGFR): >120, 90–119, 60–89, and <60 mL/min/1.73 m2. The participants with eGFR >120 mL/min/1.73 m2 showed the highest risk for MS, in the highest ALP quartiles (3.848, 95% CI, 1.876–7.892), compared to the lowest quartile. Similarly, the highest risk for DM, in the highest ALP quartiles, was observed in participants with eGFR >120 ml/min/1.73 m2 (2.166, 95% CI, 1.084–4.329). ALP quartiles were significantly associated with albuminuria in participants with eGFR ≥ 60 ml/min/1.73m2. The highest ALP quartile had a 1.631-fold risk elevation for albuminuria with adjustment of age and sex. (95% CI, 1.158-2.297, P = 0.005). After adjustment, the highest ALP quartile had a 1.624-fold risk elevation, for renal hyperfiltration (95% CI, 1.204–2.192, P = 0.002). In addition, hyperfiltration was significantly associated with hemoglobin, triglyceride, white blood cell count, DM, smoking, and alcohol consumption (P<0.05). The relationship between serum ALP and metabolic disorders is stronger in participants with an upper-normal range of eGFR. Higher ALP levels are significantly associated with renal hyperfiltration in Korean general population. PMID:25853240

  2. Expression of neuron specific phosphatase, striatal enriched phosphatase (STEP) in reactive astrocytes after transient forebrain ischemia.

    PubMed

    Hasegawa, S; Morioka, M; Goto, S; Korematsu, K; Okamura, A; Yano, S; Kai, Y; Hamada, J I; Ushio, Y

    2000-02-15

    We studied the distribution and change of striatal enriched phosphatase (STEP) in the gerbil hippocampus after transient forebrain ischemia. STEP was expressed in the perikarya and in neuronal processes; it was not detected in non-neuronal cells of control animals. After 5-min forebrain ischemia, STEP immunoreactivity (STEP-IR) was preserved for 2 days; it disappeared 4 and more days after ischemia with completion of delayed neuronal death (DND) in the CA1 subfield. Furthermore, only in the CA1 after ischemia, STEP was expressed in reactive astrocytes for 4 to 28 days, showing different patterns of glial fibrillary acidic protein (GFAP)-positive reactive astrocytes. After non-or less-than lethal ischemia, STEP expression in reactive astrocytes corresponded with the degree of neuronal degeneration. Immunoblot analysis of the CA1 subfield revealed the expression of three isoforms, STEP45, -56 and -61; their expression patterns changed with time after ischemia. These data suggest that neuronal STEP is preserved until cell degeneration after ischemia and that STEP is expressed in reactive astrocytes only after lethal ischemia, with different expression patterns for its isoforms. Of STEP45, -56 and -61, STEP61 was the most strongly expressed in the reactive astrocytes; both STEP45 and -61 were expressed in neurons and the expression of STEP56 was weak. STEP may play an important role not only in neurons but also in reactive astrocytes after ischemia, depending on neuronal degeneration. PMID:10652442

  3. Electron microscope histochemical localization of alkaline phosphatase(s) in Bacillus licheniformis.

    PubMed Central

    McNicholas, J M; Hulett, F M

    1977-01-01

    Sites of alkaline phosphatase (APase) activity in a facultative thermophilic strain of Bacillus licheniformis MC14 have been localized by electron microscope histochemistry, using a lead capture method. The effects of 3% glutaraldehyde and 3.0 mM lead on APase activity were investigated, and these compounds were found to significantly inhibit enzyme activity, 68 and 18%, respectively. A number of parameters were varied in studies to localize APase activity, including: growth temperature (55 and 37 degrees C); substrate concentration in the histochemical mixture (0.06, 0.15, 0.30, 1.00 mM); fixatives; protoplast preparations and whole cells; phosphate-repressed and -derepressed cells; and age of vegetative cells (mid-log and late log). These variations affected the number but not the location of lead phosphate deposits, which appeared at discrete sites along the inner side of the cytoplasmic membrane. Control cells incubated in histochemical mixtures lacking substrate, lead, or both exhibited no lead phosphate depositis. The histochemical localization at membrane sites correlated well with biochemical localization data, which indicated that greater than 80% of the APase activity was associated with the membrane fraction in logarithmically growing cells. Images PMID:401501

  4. Electron microscope histochemical localization of alkaline phosphatase(s) in Bacillus licheniformis.

    PubMed

    McNicholas, J M; Hulett, F M

    1977-01-01

    Sites of alkaline phosphatase (APase) activity in a facultative thermophilic strain of Bacillus licheniformis MC14 have been localized by electron microscope histochemistry, using a lead capture method. The effects of 3% glutaraldehyde and 3.0 mM lead on APase activity were investigated, and these compounds were found to significantly inhibit enzyme activity, 68 and 18%, respectively. A number of parameters were varied in studies to localize APase activity, including: growth temperature (55 and 37 degrees C); substrate concentration in the histochemical mixture (0.06, 0.15, 0.30, 1.00 mM); fixatives; protoplast preparations and whole cells; phosphate-repressed and -derepressed cells; and age of vegetative cells (mid-log and late log). These variations affected the number but not the location of lead phosphate deposits, which appeared at discrete sites along the inner side of the cytoplasmic membrane. Control cells incubated in histochemical mixtures lacking substrate, lead, or both exhibited no lead phosphate depositis. The histochemical localization at membrane sites correlated well with biochemical localization data, which indicated that greater than 80% of the APase activity was associated with the membrane fraction in logarithmically growing cells. PMID:401501

  5. Inositol Polyphosphate 4-Phosphatase B as A Regulator of Bone Mass in Mice and Human

    PubMed Central

    Ferron, Mathieu; Boudiffa, Maya; Arsenault, Michel; Rached, Mohamed; Pata, Monica; Giroux, Sylvie; Elfassihi, Latifa; Kisseleva, Marina; Majerus, Philip W; Rousseau, François; Vacher, Jean

    2011-01-01

    Summary Osteoporosis is a multifactorial genetic disease characterized by reduction of bone mass due to dysregulation of osteoclast differentiation or maturation. Herein, we identified a novel regulator of osteoclastogenesis, the murine homologue of inositol polyphosphate 4-phosphatase type IIa (Inpp4bα). Expression of Inpp4bα is detected from early osteoclast differentiation to activation stage. Targeted expression of native Inpp4bα ex-vivo repressed whereas phosphatase-inactive Inpp4ba stimulated osteoclast differentiation. Inpp4bα acts on intracellular calcium level that modulates NFATc1 nuclear translocation and activation. In vivo mice deficient in Inpp4b displayed increased osteoclast differentiation rate and potential resulting in decreased bone mass and osteoporosis. Importantly, INPP4B in human was identified as a susceptibility locus for osteoporosis. This study defined Inpp4b as a major modulator of the osteoclast differentiation and as a gene linked to variability of bone mineral density in mice and humans. PMID:21982707

  6. Specific inhibitors of the protein tyrosine phosphatase Shp2 identified by high-throughput docking

    PubMed Central

    Hellmuth, Klaus; Grosskopf, Stefanie; Lum, Ching Tung; Würtele, Martin; Röder, Nadine; von Kries, Jens Peter; Rosario, Marta; Rademann, Jörg; Birchmeier, Walter

    2008-01-01

    The protein tyrosine phosphatase Shp2 is a positive regulator of growth factor signaling. Gain-of-function mutations in several types of leukemia define Shp2 as a bona fide oncogene. We performed a high-throughput in silico screen for small-molecular-weight compounds that bind the catalytic site of Shp2. We have identified the phenylhydrazonopyrazolone sulfonate PHPS1 as a potent and cell-permeable inhibitor, which is specific for Shp2 over the closely related tyrosine phosphatases Shp1 and PTP1B. PHPS1 inhibits Shp2-dependent cellular events such as hepatocyte growth factor/scatter factor (HGF/SF)-induced epithelial cell scattering and branching morphogenesis. PHPS1 also blocks Shp2-dependent downstream signaling, namely HGF/SF-induced sustained phosphorylation of the Erk1/2 MAP kinases and dephosphorylation of paxillin. Furthermore, PHPS1 efficiently inhibits activation of Erk1/2 by the leukemia-associated Shp2 mutant, Shp2-E76K, and blocks the anchorage-independent growth of a variety of human tumor cell lines. The PHPS compound class is therefore suitable for further development of therapeutics for the treatment of Shp2-dependent diseases. PMID:18480264

  7. A family of metal-dependent phosphatases implicated in metabolite damage-control.

    PubMed

    Huang, Lili; Khusnutdinova, Anna; Nocek, Boguslaw; Brown, Greg; Xu, Xiaohui; Cui, Hong; Petit, Pierre; Flick, Robert; Zallot, Rémi; Balmant, Kelly; Ziemak, Michael J; Shanklin, John; de Crécy-Lagard, Valérie; Fiehn, Oliver; Gregory, Jesse F; Joachimiak, Andrzej; Savchenko, Alexei; Yakunin, Alexander F; Hanson, Andrew D

    2016-08-01

    DUF89 family proteins occur widely in both prokaryotes and eukaryotes, but their functions are unknown. Here we define three DUF89 subfamilies (I, II, and III), with subfamily II being split into stand-alone proteins and proteins fused to pantothenate kinase (PanK). We demonstrated that DUF89 proteins have metal-dependent phosphatase activity against reactive phosphoesters or their damaged forms, notably sugar phosphates (subfamilies II and III), phosphopantetheine and its S-sulfonate or sulfonate (subfamily II-PanK fusions), and nucleotides (subfamily I). Genetic and comparative genomic data strongly associated DUF89 genes with phosphoester metabolism. The crystal structure of the yeast (Saccharomyces cerevisiae) subfamily III protein YMR027W revealed a novel phosphatase active site with fructose 6-phosphate and Mg(2+) bound near conserved signature residues Asp254 and Asn255 that are critical for activity. These findings indicate that DUF89 proteins are previously unrecognized hydrolases whose characteristic in vivo function is to limit potentially harmful buildups of normal or damaged phosphometabolites. PMID:27322068

  8. Identification and Structural Characterization of a Legionella Phosphoinositide Phosphatase*

    PubMed Central

    Toulabi, Leila; Wu, Xiaochun; Cheng, Yanshu; Mao, Yuxin

    2013-01-01

    Bacterial pathogen Legionella pneumophila is the causative agent of Legionnaires' disease, which is associated with intracellular replication of the bacteria in macrophages of human innate immune system. Recent studies indicate that pathogenic bacteria can subvert host cell phosphoinositide (PI) metabolism by translocated virulence effectors. However, in which manner Legionella actively exploits PI lipids to benefit its infection is not well characterized. Here we report that L. pneumophila encodes an effector protein, named SidP, that functions as a PI-3-phosphatase specifically hydrolyzing PI(3)P and PI(3,5)P2 in vitro. This activity of SidP rescues the growth phenotype of a yeast strain defective in PI(3)P phosphatase activity. Crystal structure of SidP orthologue from Legionella longbeachae reveals that this unique PI-3-phosphatase is composed of three distinct domains: a large catalytic domain, an appendage domain that is inserted into the N-terminal portion of the catalytic domain, and a C-terminal α-helical domain. SidP has a small catalytic pocket that presumably provides substrate specificity by limiting the accessibility of bulky PIs with multiple phosphate groups. Together, our identification of a unique family of Legionella PI phosphatases highlights a common scheme of exploiting host PI lipids in many intracellular bacterial pathogen infections. PMID:23843460

  9. Effects of organic dairy manure amendment on soil phosphatase activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic dairy production is increasing in the U.S. due to concerns over environmental, human, and animal health. It is well known that the application of livestock manure to soil can influence enzyme activities involved in nutrient cycling and soil fertility, such as soil phosphatases; however, orga...

  10. Enzymatic method of determining lead using alkaline phosphatase

    SciTech Connect

    Shekhovtsova, T.N.; Kucheryaeva, V.V.; Dolmanova, I.F.

    1986-03-20

    The purpose of this work was to determine the possibility of using alkaline phosphatase to determine trace amounts of ions of a number of metals - Mg, Ba, Ca, Sr, Cd, Pb - for which there are virtually no sensitive and simple methods of determination.

  11. Methods to distinguish various types of protein phosphatase activity

    SciTech Connect

    Brautigan, D.L.; Shriner, C.L.

    1988-01-01

    To distinguish the action of protein Tyr(P) and protein Ser(P)/Thr(P) phosphatases on /sup 32/P-labeled phosphoproteins in subcellular fractions different inhibitors and activators are utilized. Comparison of the effects of added compounds provides a convenient, indirect method to characterize dephosphorylation reactions. Protein Tyr(P) phosphatases are specifically inhibited by micromolar Zn2+ or vanadate, and show maximal activity in the presence of EDTA. The other class of cellular phosphatases, specific for protein Ser(P) and Thr(P) residues, are inhibited by fluoride and EDTA. In this class of enzymes two major functional types can be distinguished: those sensitive to inhibition by the heat-stable protein inhibitor-2 and not stimulated by polycations, and those not sensitive to inhibition and stimulated by polycations. Preparation of /sup 32/P-labeled Tyr(P) and Ser(P) phosphoproteins also is presented for the direct measurement of phosphatase activities in preparations by the release of acid-soluble (/sup 32/P)phosphate.

  12. Functional Diversity of Haloacid Dehalogenase Superfamily Phosphatases from Saccharomyces cerevisiae

    PubMed Central

    Kuznetsova, Ekaterina; Nocek, Boguslaw; Brown, Greg; Makarova, Kira S.; Flick, Robert; Wolf, Yuri I.; Khusnutdinova, Anna; Evdokimova, Elena; Jin, Ke; Tan, Kemin; Hanson, Andrew D.; Hasnain, Ghulam; Zallot, Rémi; de Crécy-Lagard, Valérie; Babu, Mohan; Savchenko, Alexei; Joachimiak, Andrzej; Edwards, Aled M.; Koonin, Eugene V.; Yakunin, Alexander F.

    2015-01-01

    The haloacid dehalogenase (HAD)-like enzymes comprise a large superfamily of phosphohydrolases present in all organisms. The Saccharomyces cerevisiae genome encodes at least 19 soluble HADs, including 10 uncharacterized proteins. Here, we biochemically characterized 13 yeast phosphatases from the HAD superfamily, which includes both specific and promiscuous enzymes active against various phosphorylated metabolites and peptides with several HADs implicated in detoxification of phosphorylated compounds and pseudouridine. The crystal structures of four yeast HADs provided insight into their active sites, whereas the structure of the YKR070W dimer in complex with substrate revealed a composite substrate-binding site. Although the S. cerevisiae and Escherichia coli HADs share low sequence similarities, the comparison of their substrate profiles revealed seven phosphatases with common preferred substrates. The cluster of secondary substrates supporting significant activity of both S. cerevisiae and E. coli HADs includes 28 common metabolites that appear to represent the pool of potential activities for the evolution of novel HAD phosphatases. Evolution of novel substrate specificities of HAD phosphatases shows no strict correlation with sequence divergence. Thus, evolution of the HAD superfamily combines the conservation of the overall substrate pool and the substrate profiles of some enzymes with remarkable biochemical and structural flexibility of other superfamily members. PMID:26071590

  13. Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

    ERIC Educational Resources Information Center

    Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika

    2010-01-01

    This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…

  14. Gossypol inhibits calcineurin phosphatase activity at multiple sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcineurin, the calcium/calmodulin dependant serine/threonine phosphatase is the target for the immunosuppressant drugs FK506 and cyclosporine A. These calcineurin inhibitors each require an immunophilin protein cofactor. Gossypol, a polyphenol produced by the cotton plant, inhibits calcineurin, ...

  15. Phosphatase inhibitors activate normal and defective CFTR chloride channels.

    PubMed Central

    Becq, F; Jensen, T J; Chang, X B; Savoia, A; Rommens, J M; Tsui, L C; Buchwald, M; Riordan, J R; Hanrahan, J W

    1994-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is regulated by phosphorylation and dephosphorylation at multiple sites. Although activation by protein kinases has been studied in some detail, the dephosphorylation step has received little attention. This report examines the mechanisms responsible for the dephosphorylation and spontaneous deactivation ("rundown") of CFTR chloride channels excised from transfected Chinese hamster ovary (CHO) and human airway epithelial cells. We report that the alkaline phosphatase inhibitors bromotetramisole, 3-isobutyl-1-methylxanthine, theophylline, and vanadate slow the rundown of CFTR channel activity in excised membrane patches and reduce dephosphorylation of CFTR protein in isolated membranes. It was also found that in unstimulated cells, CFTR channels can be activated by exposure to phosphatase inhibitors alone. Most importantly, exposure of mammalian cells to phosphatase inhibitors alone activates CFTR channels that have disease-causing mutations, provided the mutant channels are present in the plasma membrane (R117H, G551D, and delta F508 after cooling). These results suggest that CFTR dephosphorylation is dynamic and that membrane-associated phosphatase activity may be a potential therapeutic target for the treatment of cystic fibrosis. Images PMID:7522329

  16. Phosphatase inhibitors activate normal and defective CFTR chloride channels.

    PubMed

    Becq, F; Jensen, T J; Chang, X B; Savoia, A; Rommens, J M; Tsui, L C; Buchwald, M; Riordan, J R; Hanrahan, J W

    1994-09-13

    The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is regulated by phosphorylation and dephosphorylation at multiple sites. Although activation by protein kinases has been studied in some detail, the dephosphorylation step has received little attention. This report examines the mechanisms responsible for the dephosphorylation and spontaneous deactivation ("rundown") of CFTR chloride channels excised from transfected Chinese hamster ovary (CHO) and human airway epithelial cells. We report that the alkaline phosphatase inhibitors bromotetramisole, 3-isobutyl-1-methylxanthine, theophylline, and vanadate slow the rundown of CFTR channel activity in excised membrane patches and reduce dephosphorylation of CFTR protein in isolated membranes. It was also found that in unstimulated cells, CFTR channels can be activated by exposure to phosphatase inhibitors alone. Most importantly, exposure of mammalian cells to phosphatase inhibitors alone activates CFTR channels that have disease-causing mutations, provided the mutant channels are present in the plasma membrane (R117H, G551D, and delta F508 after cooling). These results suggest that CFTR dephosphorylation is dynamic and that membrane-associated phosphatase activity may be a potential therapeutic target for the treatment of cystic fibrosis. PMID:7522329

  17. Structural and functional basis of protein phosphatase 5 substrate specificity

    PubMed Central

    Oberoi, Jasmeen; Dunn, Diana M.; Woodford, Mark R.; Mariotti, Laura; Schulman, Jacqualyn; Bourboulia, Dimitra; Mollapour, Mehdi

    2016-01-01

    The serine/threonine phosphatase protein phosphatase 5 (PP5) regulates hormone- and stress-induced cellular signaling by association with the molecular chaperone heat shock protein 90 (Hsp90). PP5-mediated dephosphorylation of the cochaperone Cdc37 is essential for activation of Hsp90-dependent kinases. However, the details of this mechanism remain unknown. We determined the crystal structure of a Cdc37 phosphomimetic peptide bound to the catalytic domain of PP5. The structure reveals PP5 utilization of conserved elements of phosphoprotein phosphatase (PPP) structure to bind substrate and provides a template for many PPP–substrate interactions. Our data show that, despite a highly conserved structure, elements of substrate specificity are determined within the phosphatase catalytic domain itself. Structure-based mutations in vivo reveal that PP5-mediated dephosphorylation is required for kinase and steroid hormone receptor release from the chaperone complex. Finally, our data show that hyper- or hypoactivity of PP5 mutants increases Hsp90 binding to its inhibitor, suggesting a mechanism to enhance the efficacy of Hsp90 inhibitors by regulation of PP5 activity in tumors. PMID:27466404

  18. Defining an emerging disease.

    PubMed

    Moutou, F; Pastoret, P-P

    2015-04-01

    Defining an emerging disease is not straightforward, as there are several different types of disease emergence. For example, there can be a 'real' emergence of a brand new disease, such as the emergence of bovine spongiform encephalopathy in the 1980s, or a geographic emergence in an area not previously affected, such as the emergence of bluetongue in northern Europe in 2006. In addition, disease can emerge in species formerly not considered affected, e.g. the emergence of bovine tuberculosis in wildlife species since 2000 in France. There can also be an unexpected increase of disease incidence in a known area and a known species, or there may simply be an increase in our knowledge or awareness of a particular disease. What all these emerging diseases have in common is that human activity frequently has a role to play in their emergence. For example, bovine spongiform encephalopathy very probably emerged as a result of changes in the manufacturing of meat-and-bone meal, bluetongue was able to spread to cooler climes as a result of uncontrolled trade in animals, and a relaxation of screening and surveillance for bovine tuberculosis enabled the disease to re-emerge in areas that had been able to drastically reduce the number of cases. Globalisation and population growth will continue to affect the epidemiology of diseases in years to come and ecosystems will continue to evolve. Furthermore, new technologies such as metagenomics and high-throughput sequencing are identifying new microorganisms all the time. Change is the one constant, and diseases will continue to emerge, and we must consider the causes and different types of emergence as we deal with these diseases in the future. PMID:26470448

  19. Phosphatase acitivity as biosignatures in terrestrial extreme environments

    NASA Astrophysics Data System (ADS)

    Kawai, Jun; Nakamoto, Saki; Hara, Masashi; Obayashi, Yumiko; Kaneko, Takeo; Mita, Hajime; Yoshimura, Yoshitaka; Takano, Yoshinori; Kobayashi, Kensei

    Since phosphate esters are essential for the terrestrial life, phosphatase activity can be a can-didate for biosignatures of biological activity. It has been recognized that terrestrial biosphere expands to such extreme environments as deep subsurface lithosphere, high temperature hot springs and stratosphere. We analyzed phosphatase activities in the samples obtained in ex-treme environments such as submarine hydrothermal systems and Antarctica , and discussed whether they can be used as biosignatures for extant life. Core samples and chimney samples were collected at Tarama Knoll in Okinawa Trough in 2009, both in a part of the Archaean Park Project. Surface soil samples are obtained at the Sites 1-8 near Showa Base in Antarctica during the 47th Japan Antarctic exploration mission in 2005-6. Alkaline Phosphatase activ-ity in sea water and in soil was measured spectrometrically by using 25 mM p-nitrophenyl phosphate (pH 8.0) as a substrate. Phosphatase activities in extracts were measured fluoro-metrically by using 4-methylumberyferryl phosphate as a substrate. Concentration of amino acids and their enantiomeric ratios were also determined by HPLC . Significant enzymatic ac-tivities were revealed in both some of the hydrothermal sub-vent systems and Antarctica soils, which is crucial evidence of vigorous microbial oasis. It is consistent with the fact that large enantiomeric excess of L-form amino acids were found in the same core sequences. Optimum temperatures of ALP in the chimney, Antarctica soil and YNU campus soil were 353 K, 313 K, and 333 K, respectively. The present results suggested that phosphatase activities,, together with amino acids, can be used as possible biosignatures for extant life.

  20. Probing the origins of catalytic discrimination between phosphate and sulfate monoester hydrolysis: comparative analysis of alkaline phosphatase and protein tyrosine phosphatases.

    PubMed

    Andrews, Logan D; Zalatan, Jesse G; Herschlag, Daniel

    2014-11-01

    Catalytic promiscuity, the ability of enzymes to catalyze multiple reactions, provides an opportunity to gain a deeper understanding of the origins of catalysis and substrate specificity. Alkaline phosphatase (AP) catalyzes both phosphate and sulfate monoester hydrolysis reactions with a ∼10(10)-fold preference for phosphate monoester hydrolysis, despite the similarity between these reactions. The preponderance of formal positive charge in the AP active site, particularly from three divalent metal ions, was proposed to be responsible for this preference by providing stronger electrostatic interactions with the more negatively charged phosphoryl group versus the sulfuryl group. To test whether positively charged metal ions are required to achieve a high preference for the phosphate monoester hydrolysis reaction, the catalytic preference of three protein tyrosine phosphatases (PTPs), which do not contain metal ions, were measured. Their preferences ranged from 5 × 10(6) to 7 × 10(7), lower than that for AP but still substantial, indicating that metal ions and a high preponderance of formal positive charge within the active site are not required to achieve a strong catalytic preference for phosphate monoester over sulfate monoester hydrolysis. The observed ionic strength dependences of kcat/KM values for phosphate and sulfate monoester hydrolysis are steeper for the more highly charged phosphate ester with both AP and the PTP Stp1, following the dependence expected based on the charge difference of these two substrates. However, the dependences for AP were not greater than those of Stp1 and were rather shallow for both enzymes. These results suggest that overall electrostatics from formal positive charge within the active site is not the major driving force in distinguishing between these reactions and that substantial discrimination can be attained without metal ions. Thus, local properties of the active site, presumably including multiple positioned dipolar

  1. Protein phosphatase 2A: a highly regulated family of serine/threonine phosphatases implicated in cell growth and signalling.

    PubMed Central

    Janssens, V; Goris, J

    2001-01-01

    Protein phosphatase 2A (PP2A) comprises a family of serine/threonine phosphatases, minimally containing a well conserved catalytic subunit, the activity of which is highly regulated. Regulation is accomplished mainly by members of a family of regulatory subunits, which determine the substrate specificity, (sub)cellular localization and catalytic activity of the PP2A holoenzymes. Moreover, the catalytic subunit is subject to two types of post-translational modification, phosphorylation and methylation, which are also thought to be important regulatory devices. The regulatory ability of PTPA (PTPase activator), originally identified as a protein stimulating the phosphotyrosine phosphatase activity of PP2A, will also be discussed, alongside the other regulatory inputs. The use of specific PP2A inhibitors and molecular genetics in yeast, Drosophila and mice has revealed roles for PP2A in cell cycle regulation, cell morphology and development. PP2A also plays a prominent role in the regulation of specific signal transduction cascades, as witnessed by its presence in a number of macromolecular signalling modules, where it is often found in association with other phosphatases and kinases. Additionally, PP2A interacts with a substantial number of other cellular and viral proteins, which are PP2A substrates, target PP2A to different subcellular compartments or affect enzyme activity. Finally, the de-regulation of PP2A in some specific pathologies will be touched upon. PMID:11171037

  2. Formation and properties of organo-phosphatase complexes by abiotic and biotic polymerization of pyrogallol-phosphatase mixtures.

    PubMed

    Rao, Maria A; Del Gaudio, Stefania; Scelza, Rosalia; Gianfreda, Liliana

    2010-04-28

    In this paper, the catalytic efficacy of peroxidase and manganese oxide, both commonly present in soil, to catalyze the formation of pyrogallol-phosphatase complexes was compared. The influence of several factors (e.g., the concentration of pyrogallol, the amount of catalysts, the nature of manganese oxide, birnessite, or pyrolusite, the incubation time, and the pH) on the transformation of pyrogallol and the characteristics and properties of the pyrogallol-phosphatase interaction products were investigated. The pyrogallol transformation mediated by both catalysts was very fast and increased by increasing the catalyst concentration. The nature of the catalyst also influenced the size and the molecular mass of the formed complexes. When polymerization of pyrogallol occurred with high intensity, a loss of phosphatase activity occurred, and it strongly depended on the pH at which the process was carried out and the catalyst. In particular, with peroxidase, the phosphatase activity was much lower in either suspensions or supernatants and not measurable in the insoluble complexes as compared to that measured in the presence of manganese oxides. PMID:20302357

  3. Dephosphorylation of the beta 2-adrenergic receptor and rhodopsin by latent phosphatase 2

    SciTech Connect

    Yang, S.D.; Fong, Y.L.; Benovic, J.L.; Sibley, D.R.; Caron, M.G.; Lefkowitz, R.J.

    1988-06-25

    Recent evidence suggests that the function of receptors coupled to guanine nucleotide regulatory proteins may be controlled by highly specific protein kinases, e.g. rhodopsin kinase and the beta-adrenergic receptor kinase. In order to investigate the nature of the phosphatases which might be involved in controlling the state of receptor phosphorylation we studied the ability of four highly purified well characterized protein phosphatases to dephosphorylate preparations of rhodopsin or beta 2-adrenergic receptor which had been highly phosphorylated by beta-adrenergic receptor kinase. These included: type 1 phosphatase, calcineurin phosphatase, type 2A phosphatase, and the high molecular weight latent phosphatase 2. Under conditions in which all the phosphatases could dephosphorylate such common substrates as (/sup 32/P)phosphorylase a and (/sup 32/P)myelin basic protein at similar rates only the latent phosphatase 2 was active on the phosphorylated receptors. Moreover, a latent phosphatase activity was found predominantly in a sequestered membrane fraction of frog erythrocytes. This parallels the distribution of a beta-adrenergic receptor phosphatase activity recently described in these cells. These data suggest a potential role for the latent phosphatase 2 as a specific receptor phosphatase.

  4. Enzymatic and Functional Analysis of a Protein Phosphatase, Pph3, from Myxococcus xanthus ▿

    PubMed Central

    Kimura, Yoshio; Mori, Yumi; Ina, Youhei; Takegawa, Kaoru

    2011-01-01

    A protein phosphatase, designated Pph3, from Myxococcus xanthus showed the enzymatic characteristics of PP2C-type serine/threonine protein phosphatases, which are metal ion-dependent, okadaic acid-insensitive protein phosphatases. The pph3 mutant under starvation conditions formed immature fruiting bodies and reduced sporulation. PMID:21398555

  5. Detection of endogenous alkaline phosphatase activity in intact cells by flow cytometry using the fluorogenic ELF-97 phosphatase substrate

    NASA Technical Reports Server (NTRS)

    Telford, W. G.; Cox, W. G.; Stiner, D.; Singer, V. L.; Doty, S. B.

    1999-01-01

    BACKGROUND: The alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone (ELF((R))-97 for enzyme-labeled fluorescence) has been found useful for the histochemical detection of endogenous AP activity and AP-tagged proteins and oligonucleotide probes. In this study, we evaluated its effectiveness at detecting endogenous AP activity by flow cytometry. METHODS: The ELF-97 phosphatase substrate was used to detect endogenous AP activity in UMR-106 rat osteosarcoma cells and primary cultures of chick chondrocytes. Cells were labeled with the ELF-97 reagent and analyzed by flow cytometry using an argon ultraviolet (UV) laser. For comparison purposes, cells were also assayed for AP using a Fast Red Violet LB azo dye assay previously described for use in detecting AP activity by flow cytometry. RESULTS: The ELF-97 phosphatase substrate effectively detected endogenous AP activity in UMR-106 cells, with over 95% of the resulting fluorescent signal resulting from AP-specific activity (as determined by levamisole inhibition of AP activity). In contrast, less than 70% of the fluorescent signal from the Fast Red Violet LB (FRV) assay was AP-dependent, reflecting the high intrinsic fluorescence of the unreacted components. The ELF-97 phosphatase assay was also able to detect very low AP activity in chick chondrocytes that was undetectable by the azo dye method. CONCLUSIONS: The ELF-97 phosphatase assay was able to detect endogenous AP activity in fixed mammalian and avian cells by flow cytometry with superior sensitivity to previously described assays. This work also shows the applicability of ELF-97 to flow cytometry, supplementing its previously demonstrated histochemical applications. Copyright 1999 Wiley-Liss, Inc.

  6. Structural and Biochemical Insights into the Regulation of Protein Phosphatase 2A by Small t Antigen of SV40

    SciTech Connect

    Chen,Y.; Xu, Y.; Bao, Q.; Xing, Y.; Li, Z.; Lin, Z.; Stock, J.; Jeffrey, P.; Shi, Y.

    2007-01-01

    The small t antigen (ST) of DNA tumor virus SV40 facilitates cellular transformation by disrupting the functions of protein phosphatase 2A (PP2A) through a poorly defined mechanism. The crystal structure of the core domain of SV40 ST bound to the scaffolding subunit of human PP2A reveals that the ST core domain has a novel zinc-binding fold and interacts with the conserved ridge of HEAT repeats 3-6, which overlaps with the binding site for the B' (also called PR61 or B56) regulatory subunit. ST has a lower binding affinity than B' for the PP2A core enzyme. Consequently, ST does not efficiently displace B' from PP2A holoenzymes in vitro. Notably, ST inhibits PP2A phosphatase activity through its N-terminal J domain. These findings suggest that ST may function mainly by inhibiting the phosphatase activity of the PP2A core enzyme, and to a lesser extent by modulating assembly of the PP2A holoenzymes.

  7. In vivo structure-activity relationship studies support allosteric targeting of a dual specificity phosphatase.

    PubMed

    Korotchenko, Vasiliy N; Saydmohammed, Manush; Vollmer, Laura L; Bakan, Ahmet; Sheetz, Kyle; Debiec, Karl T; Greene, Kristina A; Agliori, Christine S; Bahar, Ivet; Day, Billy W; Vogt, Andreas; Tsang, Michael

    2014-07-01

    Dual specificity phosphatase 6 (DUSP6) functions as a feedback attenuator of fibroblast growth factor signaling during development. In vitro high throughput chemical screening attempts to discover DUSP6 inhibitors have yielded limited success. However, in vivo whole-organism screens of zebrafish identified compound 1 (BCI) as an allosteric inhibitor of DUSP6. Here we designed and synthesized a panel of analogues to define the structure-activity relationship (SAR) of DUSP6 inhibition. In vivo high-content analysis in transgenic zebrafish, coupled with cell-based chemical complementation assays, identified structural features of the pharmacophore of 1 that were essential for biological activity. In vitro assays of DUSP hyperactivation corroborated the results from in vivo and cellular SAR. The results reinforce the notion that DUSPs are druggable through allosteric mechanisms and illustrate the utility of zebrafish as a model organism for in vivo SAR analyses. PMID:24909879

  8. Assays to Measure PTEN Lipid Phosphatase Activity In Vitro from Purified Enzyme or Immunoprecipitates.

    PubMed

    Spinelli, Laura; Leslie, Nicholas R

    2016-01-01

    PTEN is a one of the most frequently mutated tumor suppressors in human cancers. It is essential for regulating diverse biological processes and through its lipid phosphatase activity regulates the PI 3-Kinase signaling pathway. Sensitive phosphatase assays are employed to study the catalytic activity of PTEN against phospholipid substrates. Here we describe protocols to assay PTEN lipid phosphatase activity using either purified enzyme (purified PTEN lipid phosphatase assay) or PTEN immunopurified from tissues or cultured cells (cellular IP PTEN lipid phosphatase assay) against vesicles containing radiolabeled PIP3 substrate. PMID:27514802

  9. Promiscuity and electrostatic flexibility in the alkaline phosphatase superfamily.

    PubMed

    Pabis, Anna; Kamerlin, Shina Caroline Lynn

    2016-04-01

    Catalytic promiscuity, that is, the ability of single enzymes to facilitate the turnover of multiple, chemically distinct substrates, is a widespread phenomenon that plays an important role in the evolution of enzyme function. Additionally, such pre-existing multifunctionality can be harnessed in artificial enzyme design. The members of the alkaline phosphatase superfamily have served extensively as both experimental and computational model systems for enhancing our understanding of catalytic promiscuity. In this Opinion, we present key recent computational studies into the catalytic activity of these highly promiscuous enzymes, highlighting the valuable insight they have provided into both the molecular basis for catalytic promiscuity in general, and its implications for the evolution of phosphatase activity. PMID:26716576

  10. Mitochondrial Phosphatase PTPMT1 is essential for cardiolipin biosynthesis

    PubMed Central

    Zhang, Ji; Guan, Ziqiang; Murphy, Anne N.; Wiley, Sandra E.; Perkins, Guy A.; Worby, Carolyn A.; Engel, James L.; Heacock, Philip; Nguyen, Oanh Kim; Wang, Jonathan H.; Raetz, Christian R.H.; Dowhan, William; Dixon, Jack E.

    2011-01-01

    Summary PTPMT1 was the first protein tyrosine phosphatase found localized to the mitochondria, but its biological function was unknown. Herein, we demonstrate that whole body deletion of Ptpmt1 in mice leads to embryonic lethality, suggesting an indispensable role for PTPMT1 during development. Ptpmt1-deficiency in mouse embryonic fibroblasts compromises mitochondrial respiration and results in abnormal mitochondrial morphology. Lipid analysis of Ptpmt1-deficient fibroblasts reveals an accumulation of phosphatidylglycerophosphate (PGP) along with a concomitant decrease in phosphatidylglycerol. PGP is an essential intermediate in the biosynthetic pathway of cardiolipin, a mitochondrial-specific phospholipid regulating the membrane integrity and activities of the organelle. We further demonstrate that PTPMT1 specifically dephosphorylates PGP in vitro. Loss of PTPMT1 leads to dramatic diminution of cardiolipin, which can be partially reversed by the expression of catalytic active PTPMT1. Our study identifies PTPMT1 as the mammalian PGP phosphatase and points to its role as a regulator of cardiolipin biosynthesis. PMID:21641550

  11. Radiation inactivation analysis of rat liver microsomal glucose 6-phosphatase

    SciTech Connect

    Ness, G.C.; Sample, C.E.; McCreery, M.J.; Sukalski, K.A.; Nordlie, R.C.

    1986-05-01

    Attempts to obtain the molecular weight of microsomal glucose-6-phosphatase based on solubilization and purification have yielded widely divergent results. Since radiation inactivation analysis can be used to obtain molecular weights of proteins within the native membrane environments, this technique was applied. Identical target sizes of about 70 kd for both glucose 6-phosphate phosphohydrolase and carbamyl phosphate:glucose phosphotransferase were observed. This value was unaffected by adding deoxycholate, which disrupts the microsomal membranes, to the microsomal suspensions prior to irradiation. The data suggest that the glucose 6-phosphate transport function and the glucose 6-phosphate phosphohydrolase activity of microsomal glucose 6-phosphatase either residue on a single polypeptide or on two covalently linked polypeptides.

  12. Cytochemical characterization of yolk granule acid phosphatase during early development of the oyster Crassostrea gigas (Thunberg)

    NASA Astrophysics Data System (ADS)

    Wang, Yiyan; Sun, Hushan; Wang, Yanjie; Yan, Dongchun; Wang, Lei

    2015-03-01

    In this study, a cytochemical method and transmission electron microscopy was used to examine acid phosphatase activities of yolk granules throughout the early developmental stages of the Pacific oyster Crassostrea gigas. This study aimed to investigate the dynamic change of yolk granule acid phosphatase, and the mechanisms underlying its involvement in yolk degradation during the early developmental stages of molluscs. Three types of yolk granules (YGI, YGII, and YGIII) that differed in electron density and acid phosphatase reaction were identified in early cleavage, morula, blastula, gastrula, trochophore, and veliger stages. The morphological heterogeneities of the yolk granules were related to acid phosphatase activity and degrees of yolk degradation, indicating the association of acid phosphatase with yolk degradation in embryos and larvae of molluscs. Fusion of yolk granules was observed during embryogenesis and larval development of C. gigas. The fusion of YGI (free of acid phosphatase reaction) with YGII (rich in acid phosphatase reaction) could be the way by which yolk degradation is triggered.

  13. Cholesterol modulates alkaline phosphatase activity of rat intestinal microvillus membranes.

    PubMed

    Brasitus, T A; Dahiya, R; Dudeja, P K; Bissonnette, B M

    1988-06-25

    Experiments were conducted, using a nonspecific lipid transfer protein, to vary the cholesterol/phospholipid molar ratio of rat proximal small intestinal microvillus membranes in order to assess the possible role of cholesterol in modulating enzymatic activities of this plasma membrane. Cholesterol/phospholipid molar ratios from 0.71 to 1.30 were produced from a normal value of 1.05 by incubation with the transfer protein and an excess of either phosphatidylcholine or cholesterol/phosphatidylcholine liposomes for 60 min at 37 degrees C. Cholesterol loading or depletion of the membranes was accompanied by a decrease or increase, respectively, in their lipid fluidity, as assessed by steady-state fluorescence polarization techniques using the lipid-soluble fluorophore 1,6-diphenyl-1,3,5-hexatriene. Increasing the cholesterol/phospholipid molar ratio also decreased alkaline phosphatase specific activity by approximately 20-30%, whereas decreasing this ratio increased this enzymatic activity by 20-30%. Sucrase, maltase, and lactase specific activities were not affected in these same preparations. Since the changes in alkaline phosphatase activity could be secondary to alterations in fluidity, cholesterol, or both, additional experiments were performed using benzyl alcohol, a known fluidizer. Benzyl alcohol (25 mM) restored the fluidity of cholesterol-enriched preparations to control levels, did not change the cholesterol/phospholipid molar ratio, and failed to alter alkaline phosphatase activity. These findings, therefore, indicate that alterations in the cholesterol content and cholesterol/phospholipid molar ratio of microvillus membranes can modulate alkaline phosphatase but not sucrase, maltase, or lactase activities. Moreover, membrane fluidity does not appear to be an important physiological regulator of these enzymatic activities. PMID:3379034

  14. Metavanadate at the active site of the phosphatase VHZ.

    PubMed

    Kuznetsov, Vyacheslav I; Alexandrova, Anastassia N; Hengge, Alvan C

    2012-09-01

    Vanadate is a potent modulator of a number of biological processes and has been shown by crystal structures and NMR spectroscopy to interact with numerous enzymes. Although these effects often occur under conditions where oligomeric forms dominate, the crystal structures and NMR data suggest that the inhibitory form is usually monomeric orthovanadate, a particularly good inhibitor of phosphatases because of its ability to form stable trigonal-bipyramidal complexes. We performed a computational analysis of a 1.14 Å structure of the phosphatase VHZ in complex with an unusual metavanadate species and compared it with two classical trigonal-bipyramidal vanadate-phosphatase complexes. The results support extensive delocalized bonding to the apical ligands in the classical structures. In contrast, in the VHZ metavanadate complex, the central, planar VO(3)(-) moiety has only one apical ligand, the nucleophilic Cys95, and a gap in electron density between V and S. A computational analysis showed that the V-S interaction is primarily ionic. A mechanism is proposed to explain the formation of metavanadate in the active site from a dimeric vanadate species that previous crystallographic evidence has shown to be able to bind to the active sites of phosphatases related to VHZ. Together, the results show that the interaction of vanadate with biological systems is not solely reliant upon the prior formation of a particular inhibitory form in solution. The catalytic properties of an enzyme may act upon the oligomeric forms primarily present in solution to generate species such as the metavanadate ion observed in the VHZ structure. PMID:22876963

  15. phoD Alkaline Phosphatase Gene Diversity in Soil

    PubMed Central

    Kertesz, Michael A.; Bünemann, Else K.

    2015-01-01

    Phosphatase enzymes are responsible for much of the recycling of organic phosphorus in soils. The PhoD alkaline phosphatase takes part in this process by hydrolyzing a range of organic phosphoesters. We analyzed the taxonomic and environmental distribution of phoD genes using whole-genome and metagenome databases. phoD alkaline phosphatase was found to be spread across 20 bacterial phyla and was ubiquitous in the environment, with the greatest abundance in soil. To study the great diversity of phoD, we developed a new set of primers which targets phoD genes in soil. The primer set was validated by 454 sequencing of six soils collected from two continents with different climates and soil properties and was compared to previously published primers. Up to 685 different phoD operational taxonomic units were found in each soil, which was 7 times higher than with previously published primers. The new primers amplified sequences belonging to 13 phyla, including 71 families. The most prevalent phoD genes identified in these soils were affiliated with the orders Actinomycetales (13 to 35%), Bacillales (1 to 29%), Gloeobacterales (1 to 18%), Rhizobiales (18 to 27%), and Pseudomonadales (0 to 22%). The primers also amplified phoD genes from additional orders, including Burkholderiales, Caulobacterales, Deinococcales, Planctomycetales, and Xanthomonadales, which represented the major differences in phoD composition between samples, highlighting the singularity of each community. Additionally, the phoD bacterial community structure was strongly related to soil pH, which varied between 4.2 and 6.8. These primers reveal the diversity of phoD in soil and represent a valuable tool for the study of phoD alkaline phosphatase in environmental samples. PMID:26253682

  16. Displacement affinity chromatography of protein phosphatase one (PP1) complexes

    PubMed Central

    Moorhead, Greg BG; Trinkle-Mulcahy, Laura; Nimick, Mhairi; De Wever, Veerle; Campbell, David G; Gourlay, Robert; Lam, Yun Wah; Lamond, Angus I

    2008-01-01

    Background Protein phosphatase one (PP1) is a ubiquitously expressed, highly conserved protein phosphatase that dephosphorylates target protein serine and threonine residues. PP1 is localized to its site of action by interacting with targeting or regulatory proteins, a majority of which contains a primary docking site referred to as the RVXF/W motif. Results We demonstrate that a peptide based on the RVXF/W motif can effectively displace PP1 bound proteins from PP1 retained on the phosphatase affinity matrix microcystin-Sepharose. Subsequent co-immunoprecipitation experiments confirmed that each identified binding protein was either a direct PP1 interactor or was in a complex that contains PP1. Our results have linked PP1 to numerous new nuclear functions and proteins, including Ki-67, Rif-1, topoisomerase IIα, several nuclear helicases, NUP153 and the TRRAP complex. Conclusion This modification of the microcystin-Sepharose technique offers an effective means of purifying novel PP1 regulatory subunits and associated proteins and provides a simple method to uncover a link between PP1 and additional cellular processes. PMID:19000314

  17. Testicular acid phosphatase induces odontoblast differentiation and mineralization.

    PubMed

    Choi, Hwajung; Kim, Tak-Heun; Yun, Chi-Young; Kim, Jung-Wook; Cho, Eui-Sic

    2016-04-01

    Odontoblasts differentiate from dental mesenchyme during dentin formation and mineralization. However, the molecular mechanisms controlling odontoblast differentiation remain poorly understood. Here, we show that expression of testicular acid phosphatase (ACPT) is restricted in the early stage of odontoblast differentiation in proliferating dental mesenchymal cells and secretory odontoblasts. ACPT is expressed earlier than tissue-nonspecific alkaline phosphatase (TNAP) and partly overlaps with TNAP in differentiating odontoblasts. In MDPC-23 odontoblastic cells, expression of ACPT appears simultaneously with a decrease in β-catenin activity and is abolished with the expression of Phex and Dsp. Knockdown of ACPT in MDPC-23 cells stimulates cell proliferation together with an increase in active β-catenin and cyclin D1. In contrast, the overexpression of ACPT suppresses cell proliferation with a decrease in active β-catenin and cyclin D1. Expression of TNAP, Osx, Phex and Dsp is reduced by knockdown of ACPT but is enhanced by ACPT overexpression. When ACPT is blocked with IgG, alkaline phosphatase activity is inhibited but cell proliferation is unchanged regardless of ACPT expression. These findings suggest that ACPT inhibits cell proliferation through β-catenin-mediated signaling in dental mesenchyme but elicits odontoblast differentiation and mineralization by supplying phosphate during dentin formation. Thus, ACPT might be a novel candidate for inducing odontoblast differentiation and mineralization for dentin regeneration. PMID:26547858

  18. Purification of a specific reversible tyrosine-O-phosphate phosphatase.

    PubMed Central

    Fukami, Y; Lipmann, F

    1982-01-01

    A phosphatase specific for tyrosine-O-phosphate (Tyr-P) was separated from several nonspecific phosphatases present in the third instar larvae of Drosophila melanogaster. The enzyme hydrolyzed L-Tyr-P, with an apparent Km of 0.14 mM, but not D-Tyr-P after being freed from hydrolytic activity toward p-nitrophenyl phosphate, the common phosphatase substrate. Such purified preparations also catalyzed a reversible phosphate transfer reaction from unlabeled Tyr-P to [3H]tyrosine. The transfer activity was L4-14% of the hydrolytic activity, depending on the initial concentration of tyrosine (0.25-4.0 mM). The two activities coincided throughout purification. However, they differed in pH optimum, that of hydrolysis being 6.5-7 and that of phosphate transfer being 7.7.5. The two activities were also differentially inhibited by 1-p-bromotetramisole oxalate in the presence of EDTA and by Mn2+. Addition of Mg2+ did not affect either hydrolysis or phosphate transfer, but 5 mM Zn2+ was 65% inhibitory to both. Sodium fluoride strongly inhibited both reactions, and this inhibition was reversed by EDTA, while EDTA itself had no effect. Pi had no effect and no detectable incorporation of 32Pi into Tyr-P was observed, indicating that the phosphate transfer reaction is not a simple reversal of hydrolysis. No ATP-linked phosphorylation of tyrosine was found. PMID:6181504

  19. Centromeric binding and activity of Protein Phosphatase 4

    PubMed Central

    Lipinszki, Zoltan; Lefevre, Stephane; Savoian, Matthew S.; Singleton, Martin R.; Glover, David M.; Przewloka, Marcin R.

    2015-01-01

    The cell division cycle requires tight coupling between protein phosphorylation and dephosphorylation. However, understanding the cell cycle roles of multimeric protein phosphatases has been limited by the lack of knowledge of how their diverse regulatory subunits target highly conserved catalytic subunits to their sites of action. Phosphoprotein phosphatase 4 (PP4) has been recently shown to participate in the regulation of cell cycle progression. We now find that the EVH1 domain of the regulatory subunit 3 of Drosophila PP4, Falafel (Flfl), directly interacts with the centromeric protein C (CENP-C). Unlike other EVH1 domains that interact with proline-rich ligands, the crystal structure of the Flfl amino-terminal EVH1 domain bound to a CENP-C peptide reveals a new target-recognition mode for the phosphatase subunit. We also show that binding of Flfl to CENP-C is required to bring PP4 activity to centromeres to maintain CENP-C and attached core kinetochore proteins at chromosomes during mitosis. PMID:25562660

  20. Discovery and development of small molecule SHIP phosphatase modulators.

    PubMed

    Viernes, Dennis R; Choi, Lydia B; Kerr, William G; Chisholm, John D

    2014-07-01

    Inositol phospholipids play an important role in the transfer of signaling information across the cell membrane in eukaryotes. These signals are often governed by the phosphorylation patterns on the inositols, which are mediated by a number of inositol kinases and phosphatases. The src homology 2 (SH2) containing inositol 5-phosphatase (SHIP) plays a central role in these processes, influencing signals delivered through the PI3K/Akt/mTOR pathway. SHIP modulation by small molecules has been implicated as a treatment in a number of human disease states, including cancer, inflammatory diseases, diabetes, atherosclerosis, and Alzheimer's disease. In addition, alteration of SHIP phosphatase activity may provide a means to facilitate bone marrow transplantation and increase blood cell production. This review discusses the cellular signaling pathways and protein-protein interactions that provide the molecular basis for targeting the SHIP enzyme in these disease states. In addition, a comprehensive survey of small molecule modulators of SHIP1 and SHIP2 is provided, with a focus on the structure, potency, selectivity, and solubility properties of these compounds. PMID:24302498

  1. A PTEN-like phosphatase with a novel substrate specificity.

    PubMed

    Pagliarini, David J; Worby, Carolyn A; Dixon, Jack E

    2004-09-10

    We show that a novel PTEN-like phosphatase (PLIP) exhibits a unique preference for phosphatidylinositol 5-phosphate (PI(5)P) as a substrate in vitro. PI(5)P is the least characterized member of the phosphoinositide (PI) family of lipid signaling molecules. Recent studies suggest a role for PI(5)P in a variety of cellular events, such as tumor suppression, and in response to bacterial invasion. Determining the means by which PI(5)P levels are regulated is therefore key to understanding these cellular processes. PLIP is highly enriched in testis tissue and, similar to other PI phosphatases, exhibits poor activity against several proteinaceous substrates. Despite a recent report suggesting a role for PI(5)P in the regulation of Akt, the overexpression of wild-type or catalytically inactive PLIP in Chinese hamster ovary-insulin receptor cells or a dsRNA-mediated knockdown of PLIP mRNA levels in Drosophila S2 cells does not alter Akt activity or phosphorylation. The unique in vitro catalytic activity and detailed biochemical and kinetic analyses reported here will be of great value in our continued efforts to identify in vivo substrate(s) for this highly conserved phosphatase. PMID:15247229

  2. Phosphatidate phosphatase, a key regulator of lipid homeostasis.

    PubMed

    Pascual, Florencia; Carman, George M

    2013-03-01

    Yeast Pah1p phosphatidate phosphatase (PAP) catalyzes the penultimate step in the synthesis of triacylglycerol. PAP plays a crucial role in lipid homeostasis by controlling the relative proportions of its substrate phosphatidate and its product diacylglycerol. The cellular amounts of these lipid intermediates influence the synthesis of triacylglycerol and the pathways by which membrane phospholipids are synthesized. Physiological functions affected by PAP activity include phospholipid synthesis gene expression, nuclear/endoplasmic reticulum membrane growth, lipid droplet formation, and vacuole homeostasis and fusion. Yeast lacking Pah1p PAP activity are acutely sensitive to fatty acid-induced toxicity and exhibit respiratory deficiency. PAP is distinguished in its cellular location, catalytic mechanism, and physiological functions from Dpp1p and Lpp1p lipid phosphate phosphatases that utilize a variety of substrates that include phosphatidate. Phosphorylation/dephosphorylation is a major mechanism by which Pah1p PAP activity is regulated. Pah1p is phosphorylated by cytosolic-associated Pho85p-Pho80p, Cdc28p-cyclin B, and protein kinase A and is dephosphorylated by the endoplasmic reticulum-associated Nem1p-Spo7p phosphatase. The dephosphorylation of Pah1p stimulates PAP activity and facilitates the association with the membrane/phosphatidate allowing for its reaction and triacylglycerol synthesis. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:22910056

  3. An Alkaline Phosphatase Reporter for use in Clostridium difficile

    PubMed Central

    Edwards, Adrianne N.; Pascual, Ricardo A.; Childress, Kevin O.; Nawrocki, Kathryn L.; Woods, Emily C.; McBride, Shonna M.

    2015-01-01

    Clostridium difficile is an anaerobic, Gram-positive pathogen that causes severe gastrointestinal disease in humans and other mammals. C. difficile is notoriously difficult to work with and, until recently, few tools were available for genetic manipulation and molecular analyses. Despite the recent advances in the field, there is no simple or cost-effective technique for measuring gene transcription in C. difficile other than direct transcriptional analyses (e.g., quantitative real-time PCR and RNA-seq), which are time-consuming, expensive and difficult to scale-up. We describe the development of an in vivo reporter assay that can provide qualitative and quantitative measurements of C. difficile gene expression. Using the Enterococcus faecalis alkaline phosphatase gene, phoZ, we measured expression of C. difficile genes using a colorimetric alkaline phosphatase assay. We show that inducible alkaline phosphatase activity correlates directly with native gene expression. The ability to analyze gene expression using a standard reporter is an important and critically needed tool to study gene regulation and design genetic screens for C. difficile and other anaerobic clostridia. PMID:25576237

  4. Crystallization of recombinant Haemophilus influenzaee (P4) acid phosphatase

    SciTech Connect

    Ou, Zhonghui; Felts, Richard L.; Reilly, Thomas J.; Nix, Jay C.; Tanner, John J.

    2006-05-01

    Lipoprotein e (P4) is a class C acid phosphatase and a potential vaccine candidate for nontypeable H. influenzae infections. This paper reports the crystallization of recombinant e (P4) and the acquisition of a 1.7 Å resolution native X-ray diffraction data set. Haemophilus influenzae infects the upper respiratory tract of humans and can cause infections of the middle ear, sinuses and bronchi. The virulence of the pathogen is thought to involve a group of surface-localized macromolecular components that mediate interactions at the host–pathogen interface. One of these components is lipoprotein e (P4), which is a class C acid phosphatase and a potential vaccine candidate for nontypeable H. influenzae infections. This paper reports the crystallization of recombinant e (P4) and the acquisition of a 1.7 Å resolution native X-ray diffraction data set. The space group is P4{sub 2}2{sub 1}2, with unit-cell parameters a = 65.6, c = 101.4 Å, one protein molecule per asymmetric unit and 37% solvent content. This is the first report of the crystallization of a class C acid phosphatase.

  5. Alkaline Phosphatase-Mimicking Peptide Nanofibers for Osteogenic Differentiation.

    PubMed

    Gulseren, Gulcihan; Yasa, I Ceren; Ustahuseyin, Oya; Tekin, E Deniz; Tekinay, Ayse B; Guler, Mustafa O

    2015-07-13

    Recognition of molecules and regulation of extracellular matrix synthesis are some of the functions of enzymes in addition to their catalytic activity. While a diverse array of enzyme-like materials have been developed, these efforts have largely been confined to the imitation of the chemical structure and catalytic activity of the enzymes, and it is unclear whether enzyme-mimetic molecules can also be used to replicate the matrix-regulatory roles ordinarily performed by natural enzymes. Self-assembled peptide nanofibers can provide multifunctional enzyme-mimetic properties, as the active sequences of the target enzymes can be directly incorporated into the peptides. Here, we report enhanced bone regeneration efficiency through peptide nanofibers carrying both catalytic and matrix-regulatory functions of alkaline phosphatase, a versatile enzyme that plays a critical role in bone formation by regulating phosphate homeostasis and calcifiable bone matrix formation. Histidine presenting peptide nanostructures were developed to function as phosphatases. These molecules are able to catalyze phosphate hydrolysis and serve as bone-like nodule inducing scaffolds. Alkaline phosphatase-like peptide nanofibers enabled osteogenesis for both osteoblast-like and mesenchymal cell lines. PMID:26039144

  6. Isolation of lysophosphatidic acid phosphatase from developing peanut cotyledons.

    PubMed

    Shekar, Sunil; Tumaney, Ajay W; Rao, T J V Sreenivasa; Rajasekharan, Ram

    2002-03-01

    The soluble fraction of immature peanut (Arachis hypogaea) was capable of dephosphorylating [(3)H]lysophosphatidic acid (LPA) to generate monoacylglycerol (MAG). The enzyme responsible for the generation of MAG, LPA phosphatase, has been identified in plants and purified by successive chromatography separations on octyl-Sepharose, Blue Sepharose, Superdex-75, and heparin-agarose to apparent homogeneity from developing peanuts. This enzyme was purified 5,048-fold to a final specific activity of 858 nmol min(-1) mg(-1). The enzyme has a native molecular mass of approximately 39 kD determined by gel filtration and migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a subunit molecular mass of 39 +/- 1.5 kD. The K(m) values for oleoyl-, stearoyl-, and palmitoyl-sn-glycerol-3-phosphate were determined to be 28.6, 39.3, and 47.9 microM, respectively. The LPA phosphatase was specific to LPA and did not utilize any other substrate such as glycerol-3-phosphate, phosphatidic acid, or p-nitrophenylphosphate. The enzyme activity was stimulated by the low concentrations of detergents such as Triton X-100 and octylglucoside. Cations had no effect on the enzyme activity. Fatty acids, sphingosine, and sphingomyelin at low concentrations stimulated the enzyme activity. The identification of LPA phosphatase in plants demonstrates the existence of MAG biosynthetic machinery in plants. PMID:11891254

  7. Searching for the role of protein phosphatases in eukaryotic microorganisms.

    PubMed

    da-Silva, A M; Zapella, P D; Andrioli, L P; Campanhã, R B; Fiorini, L C; Etchebehere, L C; da-Costa-Maia, J C; Terenzi, H F

    1999-07-01

    Preference for specific protein substrates together with differential sensitivity to activators and inhibitors has allowed classification of serine/threonine protein phosphatases (PPs) into four major types designated types 1, 2A, 2B and 2C (PP1, PP2A, PP2B and PP2C, respectively). Comparison of sequences within their catalytic domains has indicated that PP1, PP2A and PP2B are members of the same gene family named PPP. On the other hand, the type 2C enzyme does not share sequence homology with the PPP members and thus represents another gene family, known as PPM. In this report we briefly summarize some of our studies about the role of serine/threonine phosphatases in growth and differentiation of three different eukaryotic models: Blastocladiella emersonii, Neurospora crassa and Dictyostelium discoideum. Our observations suggest that PP2C is the major phosphatase responsible for dephosphorylation of amidotransferase, an enzyme that controls cell wall synthesis during Blastocladiella emersonii zoospore germination. We also report the existence of a novel acid- and thermo-stable protein purified from Neurospora crassa mycelia, which specifically inhibits the PP1 activity of this fungus and mammals. Finally, we comment on our recent results demonstrating that Dictyostelium discoideum expresses a gene that codes for PP1, although this activity has never been demonstrated biochemically in this organism. PMID:10454741

  8. Isolation of Lysophosphatidic Acid Phosphatase from Developing Peanut Cotyledons1

    PubMed Central

    Shekar, Sunil; Tumaney, Ajay W.; Rao, T.J.V. Sreenivasa; Rajasekharan, Ram

    2002-01-01

    The soluble fraction of immature peanut (Arachis hypogaea) was capable of dephosphorylating [3H]lysophosphatidic acid (LPA) to generate monoacylglycerol (MAG). The enzyme responsible for the generation of MAG, LPA phosphatase, has been identified in plants and purified by successive chromatography separations on octyl-Sepharose, Blue Sepharose, Superdex-75, and heparin-agarose to apparent homogeneity from developing peanuts. This enzyme was purified 5,048-fold to a final specific activity of 858 nmol min−1 mg−1. The enzyme has a native molecular mass of approximately 39 kD determined by gel filtration and migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a subunit molecular mass of 39 ± 1.5 kD. The Km values for oleoyl-, stearoyl-, and palmitoyl-sn-glycerol-3-phosphate were determined to be 28.6, 39.3, and 47.9 μm, respectively. The LPA phosphatase was specific to LPA and did not utilize any other substrate such as glycerol-3-phosphate, phosphatidic acid, or p-nitrophenylphosphate. The enzyme activity was stimulated by the low concentrations of detergents such as Triton X-100 and octylglucoside. Cations had no effect on the enzyme activity. Fatty acids, sphingosine, and sphingomyelin at low concentrations stimulated the enzyme activity. The identification of LPA phosphatase in plants demonstrates the existence of MAG biosynthetic machinery in plants. PMID:11891254

  9. The role of serine/threonine protein phosphatases in exocytosis.

    PubMed Central

    Sim, Alistair T R; Baldwin, Monique L; Rostas, John A P; Holst, Jeff; Ludowyke, Russell I

    2003-01-01

    Modulation of exocytosis is integral to the regulation of cellular signalling, and a variety of disorders (such as epilepsy, hypertension, diabetes and asthma) are closely associated with pathological modulation of exocytosis. Emerging evidence points to protein phosphatases as key regulators of exocytosis in many cells and, therefore, as potential targets for the design of novel therapies to treat these diseases. Diverse yet exquisite regulatory mechanisms have evolved to direct the specificity of these enzymes in controlling particular cell processes, and functionally driven studies have demonstrated differential regulation of exocytosis by individual protein phosphatases. This Review discusses the evidence for the regulation of exocytosis by protein phosphatases in three major secretory systems, (1) mast cells, in which the regulation of exocytosis of inflammatory mediators plays a major role in the respiratory response to antigens, (2) insulin-secreting cells in which regulation of exocytosis is essential for metabolic control, and (3) neurons, in which regulation of exocytosis is perhaps the most complex and is essential for effective neurotransmission. PMID:12749763

  10. Peptide Microarrays for Real-Time Kinetic Profiling of Tyrosine Phosphatase Activity of Recombinant Phosphatases and Phosphatases in Lysates of Cells or Tissue Samples.

    PubMed

    Hovestad-Bijl, Liesbeth; van Ameijde, Jeroen; Pijnenburg, Dirk; Hilhorst, Riet; Liskamp, Rob; Ruijtenbeek, Rob

    2016-01-01

    A high-throughput method for the determination of the kinetics of protein tyrosine phosphatase (PTP) activity in a microarray format is presented, allowing real-time monitoring of the dephosphorylation of a 3-nitro-phosphotyrosine residue. The 3-nitro-phosphotyrosine residue is incorporated in potential PTP substrates. The peptide substrates are immobilized onto a porous surface in discrete spots. After dephosphorylation by a PTP, a 3-nitrotyrosine residue is formed that can be detected by a specific, sequence-independent antibody. The rate of dephosphorylation can be measured simultaneously on 12 microarrays, each comprising three concentrations of 48 clinically relevant peptides, using 1.0-5.0 μg of protein from a cell or tissue lysate or 0.1-2.0 μg of purified phosphatase. The data obtained compare well with solution phase assays involving the corresponding unmodified phosphotyrosine substrates. This technology, characterized by high-throughput (12 assays in less than 2 h), multiplexing and low sample requirements, facilitates convenient and unbiased investigation of the enzymatic activity of the PTP enzyme family, for instance by profiling of PTP substrate specificities, evaluation of PTP inhibitors and pinpointing changes in PTP activity in biological samples related to diseases. PMID:27514800

  11. Effects of aluminium on the hepatic inositol polyphosphate phosphatase.

    PubMed Central

    Ali, N; Craxton, A; Sumner, M; Shears, S B

    1995-01-01

    There is speculation that some of the toxic effects of Al3+ may originate from it perturbing inositol phosphate/Ca2+ signalling. For example, in permeabilized L1210 mouse lymphoma cells, 10-50 microM Al3+ activated Ins(1,3,4,5)P4-dependent Ca2+ mobilization and Ins(1,3,4,5)P4 3-phosphatase activity [Loomis-Husselbee, Cullen, Irvine and Dawson (1991) Biochem. J. 277, 883-885]. Ins(1,3,4,5)P4 3-phosphatase activity is performed by a multiple inositol polyphosphate phosphatase (MIPP) that also attacks Ins(1,3,4,5,6)P5 and InsP6 [Craxton, Ali and Shears (1995) Biochem. J. 305, 491-498]: 5-50 microM Al3+ increased MIPP activity towards both Ins(1,3,4,5)P4 (by 30%) and Ins(1,3,4,5,6)P5 (by up to 500%), without affecting metabolism of InsP6. Higher concentrations of Al3+ inhibited metabolism of all three substrates, and in the case of InsP6, Al3+ altered the pattern of accumulating products. When 1-50 microM Al3+ was present, InsP6 became a less effective inhibitor of Ins(1,3,4,5)P4 3-phosphatase activity; this effect did not depend on the presence of cellular membranes, contrary to a previous proposal. The latter phenomenon largely explains how, in a cell-free system where Ins(1,3,4,5)P4 3-phosphatase is inhibited by endogenous InsP6, the addition of Al3+ can apparently increase the enzyme activity. However, there was no effect of either 10 or 25 microM Al3+ (in either the presence or absence of apotransferrin) on inositol phosphate profiles in either Jurkat E6-1 lymphoma cells or AR4-2J pancreatoma cells. PMID:7832774

  12. Phosphatase activity of the voltage-sensing phosphatase, VSP, shows graded dependence on the extent of activation of the voltage sensor.

    PubMed

    Sakata, Souhei; Okamura, Yasushi

    2014-03-01

    The voltage-sensing phosphatase (VSP) consists of a voltage sensor and a cytoplasmic phosphatase region, and the movement of the voltage sensor is coupled to the phosphatase activity. However, its coupling mechanisms still remain unclear. One possible scenario is that the phosphatase is activated only when the voltage sensor is in a fully activated state. Alternatively, the enzymatic activity of single VSP proteins could be graded in distinct activated states of the voltage sensor, and partial activation of the voltage sensor could lead to partial activation of the phosphatase. To distinguish between these two possibilities, we studied a voltage sensor mutant of zebrafish VSP, where the voltage sensor moves in two steps as evidenced by analyses of charge movements of the voltage sensor and voltage clamp fluorometry. Measurements of the phosphatase activity toward phosphatidylinositol 4,5-bisphosphate revealed that both steps of voltage sensor activation are coupled to the tuning of phosphatase activities, consistent with the idea that the phosphatase activity is graded by the magnitude of the movement of the voltage sensor. PMID:24277865

  13. Identification of a non-purple tartrate-resistant acid phosphatase: an evolutionary link to Ser/Thr protein phosphatases?

    PubMed Central

    Hadler, Kieran S; Huber, Thomas; Cassady, A Ian; Weber, Jane; Robinson, Jodie; Burrows, Allan; Kelly, Gregory; Guddat, Luke W; Hume, David A; Schenk, Gerhard; Flanagan, Jack U

    2008-01-01

    Background Tartrate-resistant acid phosphatases (TRAcPs), also known as purple acid phosphatases (PAPs), are a family of binuclear metallohydrolases that have been identified in plants, animals and fungi. The human enzyme is a major histochemical marker for the diagnosis of bone-related diseases. TRAcPs can occur as a small form possessing only the ~35 kDa catalytic domain, or a larger ~55 kDa form possessing both a catalytic domain and an additional N-terminal domain of unknown function. Due to its role in bone resorption the 35 kDa TRAcP has become a promising target for the development of anti-osteoporotic chemotherapeutics. Findings A new human gene product encoding a metallohydrolase distantly related to the ~55 kDa plant TRAcP was identified and characterised. The gene product is found in a number of animal species, and is present in all tissues sampled by the RIKEN mouse transcriptome project. Construction of a homology model illustrated that six of the seven metal-coordinating ligands in the active site are identical to that observed in the TRAcP family. However, the tyrosine ligand associated with the charge transfer transition and purple color of TRAcPs is replaced by a histidine. Conlusion The gene product identified here may represent an evolutionary link between TRAcPs and Ser/Thr protein phosphatases. Its biological function is currently unknown but is unlikely to be associated with bone metabolism. PMID:18771593

  14. A soluble alkaline phosphatase from Bacillus licheniformis MC14. Histochemical localization, purification, characterization and comparison with the membrane-associated alkaline phosphatase.

    PubMed

    Hansa, J G; Laporta, M; Kuna, M A; Reimschuessel, R; Hulett, F M

    1981-02-13

    Growth conditions affect the quantity and distribution of alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1) in Bacillus licheniformis MC14. The soluble alkaline phosphatase, which has been found in biochemical localization studies between the cell wall and cell membrane (Glynn, J.A., Schaffel, S.D., McNicholas, J.M. and Hulett, F.M. (1977) J. Bacteriol. 129, 1010-1019), was localized via electron microscope histochemistry in cells cultured under conditions which result in increased quantities of this activity. This soluble alkaline phosphatase was stabilized with 20% glycerol and purified to homogeneity as determined by sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis. The purified enzyme is soluble in dilute buffer. This soluble alkaline phosphatase has been characterized and compared to the membrane-associated alkaline phosphatase from this organism. PMID:6783099

  15. Structural basis for the glucan phosphatase activity of Starch Excess4

    SciTech Connect

    Vander Kooi, Craig W.; Taylor, Adam O.; Pace, Rachel M.; Meekins, David A.; Guo, Hou-Fu; Kim, Youngjun; Gentry, Matthew S.

    2010-11-12

    Living organisms utilize carbohydrates as essential energy storage molecules. Starch is the predominant carbohydrate storage molecule in plants while glycogen is utilized in animals. Starch is a water-insoluble polymer that requires the concerted activity of kinases and phosphatases to solubilize the outer surface of the glucan and mediate starch catabolism. All known plant genomes encode the glucan phosphatase Starch Excess4 (SEX4). SEX4 can dephosphorylate both the starch granule surface and soluble phosphoglucans and is necessary for processive starch metabolism. The physical basis for the function of SEX4 as a glucan phosphatase is currently unclear. Herein, we report the crystal structure of SEX4, containing phosphatase, carbohydrate-binding, and C-terminal domains. The three domains of SEX4 fold into a compact structure with extensive interdomain interactions. The C-terminal domain of SEX4 integrally folds into the core of the phosphatase domain and is essential for its stability. The phosphatase and carbohydrate-binding domains directly interact and position the phosphatase active site toward the carbohydrate-binding site in a single continuous pocket. Mutagenesis of the phosphatase domain residue F167, which forms the base of this pocket and bridges the two domains, selectively affects the ability of SEX4 to function as a glucan phosphatase. Together, these results reveal the unique tertiary architecture of SEX4 that provides the physical basis for its function as a glucan phosphatase.

  16. Structural basis for the glucan phosphatase activity of Starch Excess4

    PubMed Central

    Vander Kooi, Craig W.; Taylor, Adam O.; Pace, Rachel M.; Meekins, David A.; Guo, Hou-Fu; Kim, Youngjun; Gentry, Matthew S.

    2010-01-01

    Living organisms utilize carbohydrates as essential energy storage molecules. Starch is the predominant carbohydrate storage molecule in plants while glycogen is utilized in animals. Starch is a water-insoluble polymer that requires the concerted activity of kinases and phosphatases to solubilize the outer surface of the glucan and mediate starch catabolism. All known plant genomes encode the glucan phosphatase Starch Excess4 (SEX4). SEX4 can dephosphorylate both the starch granule surface and soluble phosphoglucans and is necessary for processive starch metabolism. The physical basis for the function of SEX4 as a glucan phosphatase is currently unclear. Herein, we report the crystal structure of SEX4, containing phosphatase, carbohydrate-binding, and C-terminal domains. The three domains of SEX4 fold into a compact structure with extensive interdomain interactions. The C-terminal domain of SEX4 integrally folds into the core of the phosphatase domain and is essential for its stability. The phosphatase and carbohydrate-binding domains directly interact and position the phosphatase active site toward the carbohydrate-binding site in a single continuous pocket. Mutagenesis of the phosphatase domain residue F167, which forms the base of this pocket and bridges the two domains, selectively affects the ability of SEX4 to function as a glucan phosphatase. Together, these results reveal the unique tertiary architecture of SEX4 that provides the physical basis for its function as a glucan phosphatase. PMID:20679247

  17. Differential Requirement for Pten Lipid and Protein Phosphatase Activity during Zebrafish Embryonic Development.

    PubMed

    Stumpf, Miriam; den Hertog, Jeroen

    2016-01-01

    The lipid- and protein phosphatase PTEN is one of the most frequently mutated tumor suppressor genes in human cancers and many mutations found in tumor samples directly affect PTEN phosphatase activity. In order to understand the functional consequences of these mutations in vivo, the aim of our study was to dissect the role of Pten phosphatase activities during zebrafish embryonic development. As in other model organisms, zebrafish mutants lacking functional Pten are embryonically lethal. Zebrafish have two pten genes and pten double homozygous zebrafish embryos develop a severe pleiotropic phenotype around 4 days post fertilization, which can be largely rescued by re-introduction of pten mRNA at the one-cell stage. We used this assay to characterize the rescue-capacity of Pten and variants with mutations that disrupt lipid, protein or both phosphatase activities. The pleiotropic phenotype at 4dpf could only be rescued by wild type Pten, indicating that both phosphatase activities are required for normal zebrafish embryonic development. An earlier aspect of the phenotype, hyperbranching of intersegmental vessels, however, was rescued by Pten that retained lipid phosphatase activity, independent of protein phosphatase activity. Lipid phosphatase activity was also required for moderating pAkt levels at 4 dpf. We propose that the role of Pten during angiogenesis mainly consists of suppressing PI3K signaling via its lipid phosphatase activity, whereas the complex process of embryonic development requires lipid and protein phosphatase of Pten. PMID:26848951

  18. Differential Requirement for Pten Lipid and Protein Phosphatase Activity during Zebrafish Embryonic Development

    PubMed Central

    Stumpf, Miriam; den Hertog, Jeroen

    2016-01-01

    The lipid- and protein phosphatase PTEN is one of the most frequently mutated tumor suppressor genes in human cancers and many mutations found in tumor samples directly affect PTEN phosphatase activity. In order to understand the functional consequences of these mutations in vivo, the aim of our study was to dissect the role of Pten phosphatase activities during zebrafish embryonic development. As in other model organisms, zebrafish mutants lacking functional Pten are embryonically lethal. Zebrafish have two pten genes and pten double homozygous zebrafish embryos develop a severe pleiotropic phenotype around 4 days post fertilization, which can be largely rescued by re-introduction of pten mRNA at the one-cell stage. We used this assay to characterize the rescue-capacity of Pten and variants with mutations that disrupt lipid, protein or both phosphatase activities. The pleiotropic phenotype at 4dpf could only be rescued by wild type Pten, indicating that both phosphatase activities are required for normal zebrafish embryonic development. An earlier aspect of the phenotype, hyperbranching of intersegmental vessels, however, was rescued by Pten that retained lipid phosphatase activity, independent of protein phosphatase activity. Lipid phosphatase activity was also required for moderating pAkt levels at 4 dpf. We propose that the role of Pten during angiogenesis mainly consists of suppressing PI3K signaling via its lipid phosphatase activity, whereas the complex process of embryonic development requires lipid and protein phosphatase of Pten. PMID:26848951

  19. Controlling the Activity of a Phosphatase and Tensin Homolog (PTEN) by Membrane Potential*

    PubMed Central

    Lacroix, Jérôme; Halaszovich, Christian R.; Schreiber, Daniela N.; Leitner, Michael G.; Bezanilla, Francisco; Oliver, Dominik; Villalba-Galea, Carlos A.

    2011-01-01

    The recently discovered voltage-sensitive phosphatases (VSPs) hydrolyze phosphoinositides upon depolarization of the membrane potential, thus representing a novel principle for the transduction of electrical activity into biochemical signals. Here, we demonstrate the possibility to confer voltage sensitivity to cytosolic enzymes. By fusing the tumor suppressor PTEN to the voltage sensor of the prototypic VSP from Ciona intestinalis, Ci-VSP, we generated chimeric proteins that are voltage-sensitive and display PTEN-like enzymatic activity in a strictly depolarization-dependent manner in vivo. Functional coupling of the exogenous enzymatic activity to the voltage sensor is mediated by a phospholipid-binding motif at the interface between voltage sensor and catalytic domains. Our findings reveal that the main domains of VSPs and related phosphoinositide phosphatases are intrinsically modular and define structural requirements for coupling of enzymatic activity to a voltage sensor domain. A key feature of this prototype of novel engineered voltage-sensitive enzymes, termed Ci-VSPTEN, is the novel ability to switch enzymatic activity of PTEN rapidly and reversibly. We demonstrate that experimental control of Ci-VSPTEN can be obtained either by electrophysiological techniques or more general techniques, using potassium-induced depolarization of intact cells. Thus, Ci-VSPTEN provides a novel approach for studying the complex mechanism of activation, cellular control, and pharmacology of this important tumor suppressor. Moreover, by inducing temporally precise perturbation of phosphoinositide concentrations, Ci-VSPTEN will be useful for probing the role and specificity of these messengers in many cellular processes and to analyze the timing of phosphoinositide signaling. PMID:21454672

  20. Tissue Non-specific Alkaline Phosphatase (TNAP) in Vessels of the Brain.

    PubMed

    Deracinois, Barbara; Lenfant, Anne-Marie; Dehouck, Marie-Pierre; Flahaut, Christophe

    2015-01-01

    The microvessels of the brain represent around 3-4 % of the brain compartment but constitute the most important length (400 miles) and surface of exchange (20 m(2)) between the blood and the parenchyma of brain. Under influence of surrounding tissues, the brain microvessel endothelium expresses a specific phenotype that regulates and restricts the entry of compounds and cells from blood to brain, and defined the so-called blood-brain barrier (BBB). Evidences that alkaline phosphatase (AP) is a characteristic feature of the BBB phenotype that allows differentiating capillary endothelial cells from brain to those of the periphery have rapidly emerge. Thenceforth, AP has been rapidly used as a biomarker of the blood-brain barrier phenotype. In fact, brain capillary endothelial cells (BCECs) express exclusively tissue non-specific alkaline phosphatase (TNAP). There are several lines of evidence in favour of an important role for TNAP in brain function. TNAP is thought to be responsible for the control of transport of some compounds across the plasma membrane of the BCECs. Here, we report that levamisole-mediated inhibition of TNAP provokes an increase of the permeability to Lucifer Yellow of the endothelial monolayer. Moreover, we illustrate the disruption of the cytoskeleton organization. Interestingly, all observed effects were reversible 24 h after levamisole removal and correlated with the return of a full activity of the TNAP. This reversible effect remains to be studied in details to evaluate the potentiality of a levamisole treatment to enhance the entry of drugs in the brain parenchyma. PMID:26219710

  1. Promoting Uranium Immobilization by the Activities of Microbial Phosphatases

    SciTech Connect

    Robert J. Martinez; Melanie J. Beazley; Samuel M. Webb; Martial Taillefert; and Patricia A. Sobecky

    2007-04-19

    The overall objective of this project is to examine the activity of nonspecific phosphohydrolases present in naturally occurring subsurface microorganisms for the purpose of promoting the immobilization of radionuclides through the production of uranium [U(VI)] phosphate precipitates. Specifically, we hypothesize that the precipitation of U(VI) phosphate minerals may be promoted through the microbial release and/or accumulation of PO4 3- as a means to detoxify radionuclides and heavy metals. An experimental approach was designed to determine the extent of phosphatase activity in bacteria previously isolated from contaminated subsurface soils collected at the ERSP Field Research Center (FRC) in Oak Ridge, TN. Screening of 135 metal resistant isolates for phosphatase activity indicated the majority (75 of 135) exhibited a phosphatase-positive phenotype. During this phase of the project, a PCR based approach has also been designed to assay FRC isolates for the presence of one or more classes of the characterized non-specific acid phophastase (NSAP) genes likely to be involved in promoting U(VI) precipitation. Testing of a subset of Pb resistant (Pbr) Arthrobacter, Bacillus and Rahnella strains indicated 4 of the 9 Pbr isolates exhibited phosphatase phenotypes suggestive of the ability to bioprecipitate U(VI). Two FRC strains, a Rahnella sp. strain Y9602 and a Bacillus sp. strain Y9-2, were further characterized. The Rahnella sp. exhibited enhanced phosphatase activity relative to the Bacillus sp. Whole-cell enzyme assays identified a pH optimum of 5.5, and inorganic phosphate accumulated in pH 5.5 synthetic groundwater (designed to mimic FRC conditions) incubations of both strains in the presence of a model organophosphorus substrate provided as the sole C and P source. Kinetic experiments showed that these two organisms can grow in the presence of 200 μM dissolved uranium and that Rahnella is much more efficient in precipitating U(VI) than Bacillus sp. The

  2. Clarifying and Defining Library Services.

    ERIC Educational Resources Information Center

    Shubert, Joseph F., Ed.; Josey, E. J., Ed.

    1991-01-01

    This issue presents articles which, in some way, help to clarify and define library services. It is hoped that this clarification in library service will serve to secure the resources libraries need to serve the people of New York. The following articles are presented: (1) Introduction: "Clarifying and Defining Library Services" (Joseph F.…

  3. Crack-Defined Electronic Nanogaps.

    PubMed

    Dubois, Valentin; Niklaus, Frank; Stemme, Göran

    2016-03-01

    Achieving near-atomic-scale electronic nanogaps in a reliable and scalable manner will facilitate fundamental advances in molecular detection, plasmonics, and nanoelectronics. Here, a method is shown for realizing crack-defined nanogaps separating TiN electrodes, allowing parallel and scalable fabrication of arrays of sub-10 nm electronic nanogaps featuring individually defined gap widths. PMID:26784270

  4. Characterization of the protein tyrosine phosphatase PRL from Entamoeba histolytica.

    PubMed

    Ramírez-Tapia, Ana Lilia; Baylón-Pacheco, Lidia; Espíritu-Gordillo, Patricia; Rosales-Encina, José Luis

    2015-12-01

    Protein tyrosine phosphatase of regenerating liver (PRL) is a group of phosphatases that has not been broadly studied in protozoan parasites. In humans, PRLs are involved in metastatic cancer, the promotion of cell migration and invasion. PTPs have been increasingly recognized as important effectors of host-pathogen interactions. We characterized the only putative protein tyrosine phosphatase PRL (PTP EhPRL) in the eukaryotic human intestinal parasite Entamoeba histolytica. Here, we reported that the EhPRL protein possessed the classical HCX5R catalytic motif of PTPs and the CAAX box characteristic of the PRL family and exhibited 31-32% homology with the three human PRL isoforms. In amebae, the protein was expressed at low but detectable levels. The recombinant protein (rEhPRL) had enzymatic activity with the 3-o-methyl fluorescein phosphate (OMFP) substrate; this enzymatic activity was inhibited by the PTP inhibitor o-vanadate. Using immunofluorescence we showed that native EhPRL was localized to the cytoplasm and plasma membrane. When the trophozoites interacted with collagen, EhPRL relocalized over time to vesicle-like structures. Interaction with fibronectin increased the presence of the enzyme in the cytoplasm. Using RT-PCR, we demonstrated that EhPRL mRNA expression was upregulated when the trophozoites interacted with collagen but not with fibronectin. Trophozoites recovered from amoebic liver abscesses showed higher EhPRL mRNA expression levels than normal trophozoites. These results strongly suggest that EhPRL may play an important role in the biology and adaptive response of the parasite to the host environment during amoebic liver abscess development, thereby participating in the pathogenic mechanism. PMID:26431820

  5. Phylogenetic Characterization of Phosphatase-Expressing Bacterial Communities in Baltic Sea Sediments.

    PubMed

    Steenbergh, Anne K; Bodelier, Paul L E; Hoogveld, Hans L; Slomp, Caroline P; Laanbroek, Hendrikus J

    2015-01-01

    Phosphate release from sediments hampers the remediation of aquatic systems from a eutrophic state. Microbial phosphatases in sediments release phosphorus during organic matter degradation. Despite the important role of phosphatase-expressing bacteria, the identity of these bacteria in sediments is largely unknown. We herein presented a culture-independent method to phylogenetically characterize phosphatase-expressing bacteria in sediments. We labeled whole-cell extracts of Baltic Sea sediments with an artificial phosphatase substrate and sorted phosphatase-expressing cells with a flow cytometer. Their phylogenetic affiliation was determined by Denaturing Gradient Gel Electrophoresis. The phosphatase-expressing bacterial community coarsely reflected the whole-cell bacterial community, with a similar dominance of Alphaproteobacteria. PMID:25817584

  6. Promoting Uranium Immobilization by the Activities of Microbial Phosphatases

    SciTech Connect

    Martinez, Robert J.; Beazley, Melanie J.; Wilson, Jarad J.; Taillefert, Martial; Sobecky, Patricia A.

    2005-04-05

    The overall goal of this project is to examine the role of nonspecific phosphohydrolases present in naturally occurring subsurface microorganisms for the purpose of promoting the immobilization of radionuclides through the production of uranium [U(VI)] phosphate precipitates. Specifically, we hypothesize that the precipitation of U(VI) phosphate minerals may be promoted through the microbial release and/or accumulation of PO{sub 4}{sup 3-}. During this phase of the project we have been conducting assays to determine the effects of pH, inorganic anions and organic ligands on U(VI) mineral formation and precipitation when FRC bacterial isolates were grown in simulated groundwater medium. The molecular characterization of FRC isolates has also been undertaken during this phase of the project. Analysis of a subset of gram-positive FRC isolates cultured from FRC soils (Areas 1, 2 and 3) and background sediments have indicated a higher percentage of isolates exhibiting phosphatase phenotypes (i.e., in particular those surmised to be PO{sub 4}{sup 3-}-irrepressible) relative to isolates from the reference site. A high percentage of strains that exhibited such putatively PO{sub 4}{sup 3-}-irrepressible phosphatase phenotypes were also resistant to the heavy metals lead and cadmium. Previous work on FRC strains, including Arthrobacter, Bacillus and Rahnella spp., has demonstrated differences in tolerance to U(VI) toxicity (200 {micro}M) in the absence of organophosphate substrates. For example, Arthrobacter spp. exhibited the greatest tolerance to U(VI) while the Rahnella spp. have been shown to facilitate the precipitation of U(VI) from solution and the Bacillus spp. demonstrate the greatest sensitivity to acidic conditions and high concentrations of U(VI). PCR-based detection of FRC strains are being conducted to determine if non-specific acid phosphatases of the known molecular classes [i.e., classes A, B and C] are present in these FRC isolates. Additionally, these

  7. Graphical techniques for kinetic data analyses of alkaline phosphatase

    SciTech Connect

    Frazer, J.W.; Brand, H.R.

    1980-09-01

    The use of an automated reactor for the experimentation and on-line graphics for the rapid and exhaustive analysis of experimental data is described. Traditional (linear) methods are used for selecting the most promising model for the alkaline phosphatase catalyzed reaction from a set of ten models under consideration. Then, nonlinear techniques for model selection are used and compared with traditional techniques. In both approaches, interactive graphics techniques are used to advantage for evaluating various models and for examining the quality of the experimental data.

  8. Acid phosphatase localization in neurons of Bulla gouldiana (Gastropoda: Opisthobranchia.

    PubMed

    Robles, L J; Fisher, S K

    1975-01-01

    The organization of the ganglia and the ultrastructure of the neurons of Bulla gouldiana are similar to those described for other molluscs. Acid phosphatase positive reactions were found in the large pigmented granules, small dense bodies, multivesicular bodies, and Golgi lamellae and associated vesicles. The small dense bodies and multivesicular bodies may be stages in the formation of the larger pigmented granules which are interpreted as lysosomes. Comparison is made between the pigmented granules in Bulla and the lipofuscin bodies of vertebrate neurons. The possible involvement of these pigmented granules in the hyperpolarization of Bulla and Aplysia neurons to light is discussed. PMID:1122539

  9. A description of alkaline phosphatases from marine organisms

    NASA Astrophysics Data System (ADS)

    Tian, Jiyuan; Jia, Hongbing; Yu, Juan

    2015-12-01

    Alkaline phosphatases (APs) are non-specific phosphohydrolases, and they are widely used in clinical diagnostics and biological studies. APs are widespread in nature and exhibit different structural formulations. Based on the diversity of biogenetic sources, APs exhibit temperature-propensity traits, and they are classified as psychrophilic, mesophilic, and thermophilic. In this article, the characteristics of psychrophilic APs from marine organisms were described, accompanied by a simple description of APs from other organisms. This review will facilitate better utilization of marine APs in the biotechnology field.

  10. A description of alkaline phosphatases from marine organisms

    NASA Astrophysics Data System (ADS)

    Tian, Jiyuan; Jia, Hongbing; Yu, Juan

    2016-07-01

    Alkaline phosphatases (APs) are non-specific phosphohydrolases, and they are widely used in clinical diagnostics and biological studies. APs are widespread in nature and exhibit different structural formulations. Based on the diversity of biogenetic sources, APs exhibit temperature-propensity traits, and they are classified as psychrophilic, mesophilic, and thermophilic. In this article, the characteristics of psychrophilic APs from marine organisms were described, accompanied by a simple description of APs from other organisms. This review will facilitate better utilization of marine APs in the biotechnology field.

  11. Deactivation of free and stabilized acid phosphatase by urea.

    PubMed

    Gianfreda, L; Marrucci, G; Greco, G

    1986-11-01

    Tests on acid phosphatase (E.G. 3.1.3.2) deactivation by urea have been performed at two pH values. Two conditions have been used: native enzyme operating batch-wise in dilute solution and stabilized enzyme in continuous flow ultrafiltration membrane reactor. Stabilization is achieved by confining the enzyme within a concentrated solution of a linear chain polymer that forms a polarization layer over the membrane. The results provide significant information on the kinetics and thermodynamics of the complex phenomena taking place during deactivation. Deactivation by urea is also compared with thermal deactivation. PMID:18555278

  12. Regulation of Eye Development by Protein Serine/Threonine Phosphatases-1 and -2A.

    PubMed

    Wang, L; Yang, Y; Gong, X-D; Huang, Z-X; Nie, Q; Wang, Z-F; Ji, W-K; Hu, X-H; Hu, W-F; Gong, L-L; Zhang, L; Huang, S; Qi, R-L; Yang, T-H; Chen, Z-G; Liu, W-B; Liu, Y-Z; Li, D W-C

    2015-01-01

    The protein serine/threonine phosphatases-1 and -2A are major cellular phosphatases, playing a fundamental role in organisms from prokaryotes to eukaryotes. They contribute to 90% dephosphorylation in eukaryote proteins. In the eye, both phosphatases are highly expressed and display important functions in regulating normal eye development. Moreover, they are implicated in pathogenesis through modulation of stress-induced apoptosis. Here we review the recent progresses on these aspects. PMID:26592247

  13. Chemostat Culture of Escherichia coli K-12 Limited by the Activity of Alkaline Phosphatase

    PubMed Central

    King, Stagg L.; Francis, J. C.

    1975-01-01

    The growth-limiting reaction of a chemostat culture of Escherichia coli K-12 was the hydrolysis of β-glycerophosphate by alkaline phosphatase. The culture was buffered at pH 5.2 where alkaline phosphatase was unable to supply phosphate to the cell at a rate sufficient to sustain the maximum rate of growth. Alkaline phosphatase activity in this system is discussed in terms of the so-called Flip-Flop mechanism. PMID:240310

  14. Ptc1 protein phosphatase 2C contributes to glucose regulation of SNF1/AMP-activated protein kinase (AMPK) in Saccharomyces cerevisiae.

    PubMed

    Ruiz, Amparo; Xu, Xinjing; Carlson, Marian

    2013-10-25

    The SNF1/AMP-activated protein kinases (AMPKs) function in energy regulation in eukaryotic cells. SNF1/AMPKs are αβγ heterotrimers that are activated by phosphorylation of the activation loop Thr on the catalytic subunit. Protein kinases that activate SNF1/AMPK have been identified, but the protein phosphatases responsible for dephosphorylation of the activation loop are less well defined. For Saccharomyces cerevisiae SNF1/AMPK, Reg1-Glc7 protein phosphatase 1 and Sit4 type 2A-related phosphatase function together to dephosphorylate Thr-210 on the Snf1 catalytic subunit during growth on high concentrations of glucose; reg1Δ and sit4Δ single mutations do not impair dephosphorylation when inappropriate glycogen synthesis, also caused by these mutations, is blocked. We here present evidence that Ptc1 protein phosphatase 2C also has a role in dephosphorylation of Snf1 Thr-210 in vivo. The sit4Δ ptc1Δ mutant exhibited partial defects in regulation of the phosphorylation state of Snf1. The reg1Δ ptc1Δ mutant was viable only when expressing mutant Snf1 proteins with reduced kinase activity, and Thr-210 phosphorylation of the mutant SNF1 heterotrimers was substantially elevated during growth on high glucose. This evidence, together with findings on the reg1Δ sit4Δ mutant, indicates that although Reg1-Glc7 plays the major role, all three phosphatases contribute to maintenance of the Snf1 activation loop in the dephosphorylated state during growth on high glucose. Ptc1 has overlapping functions with Reg1-Glc7 and Sit4 in glucose regulation of SNF1/AMPK and cell viability. PMID:24019512

  15. Viewing serine/threonine protein phosphatases through the eyes of drug designers

    PubMed Central

    Zhang, Mengmeng; Yogesha, S. D.; Mayfield, Joshua E.; Gill, Gordon N.; Zhang, Yan

    2015-01-01

    Protein phosphatases, as the counterpart to protein kinases, are essential for homeostatic balance of cell signaling. Small chemical compounds that modulate the specific activity of phosphatases can be powerful tools to elucidate the biological functions of these enzymes. More importantly, many phosphatases are central players in the development of pathological pathways where inactivation can reverse or delay the onset of human diseases. Therefore, potent inhibitors for such phosphatases can be of great therapeutic benefit. In contrast to the seemingly identical enzymatic mechanism and structural characterization of eukaryotic protein kinases, protein phosphatases evolved from diverse ancestors, resulting in different domain architectures, reaction mechanisms and active site properties. In this review, we will discuss for each family of serine/threonine protein phosphatases, their involvement in biological process and corresponding strategies for small chemical intervention. Recent advances in modern drug discovery technologies have markedly facilitated the identification of selective inhibitors for some members of the phosphatase family. Furthermore, the rapid growth in knowledge about structure-activity relationships related to possible new drug targets has aided the discovery of natural product inhibitors for phosphatase family. This review summarizes the current state of investigation of the small molecules that regulate the function of serine/threonine phosphatases, the challenges presented and also strategies to overcome these obstacles. PMID:23937612

  16. Allosteric Inhibitors of the Eya2 Phosphatase Are Selective and Inhibit Eya2-mediated Cell Migration*

    PubMed Central

    Krueger, Aaron B.; Drasin, David J.; Lea, Wendy A.; Patrick, Aaron N.; Patnaik, Samarjit; Backos, Donald S.; Matheson, Christopher J.; Hu, Xin; Barnaeva, Elena; Holliday, Michael J.; Blevins, Melanie A.; Robin, Tyler P.; Eisenmesser, Elan Z.; Ferrer, Marc; Simeonov, Anton; Southall, Noel; Reigan, Philip; Marugan, Juan; Ford, Heide L.; Zhao, Rui

    2014-01-01

    Eya proteins are essential co-activators of the Six family of transcription factors and contain a unique tyrosine phosphatase domain belonging to the haloacid dehalogenase family of phosphatases. The phosphatase activity of Eya is important for the transcription of a subset of Six1-target genes, and also directs cells to the repair rather than apoptosis pathway upon DNA damage. Furthermore, Eya phosphatase activity has been shown to mediate transformation, invasion, migration, and metastasis of breast cancer cells, making it a potential new drug target for breast cancer. We have previously identified a class of N-arylidenebenzohydrazide compounds that specifically inhibit the Eya2 phosphatase. Herein, we demonstrate that these compounds are reversible inhibitors that selectively inhibit the phosphatase activity of Eya2, but not Eya3. Our mutagenesis results suggest that this class of compounds does not bind to the active site and the binding does not require the coordination with Mg2+. Moreover, these compounds likely bind within a site on the opposite face of the active site, and function as allosteric inhibitors. We also demonstrate that this class of compounds inhibits Eya2 phosphatase-mediated cell migration, setting the foundation for these molecules to be developed into chemical probes for understanding the specific function of the Eya2 phosphatase and to serve as a prototype for the development of Eya2 phosphatase specific anti-cancer drugs. PMID:24755226

  17. Allosteric inhibitors of the Eya2 phosphatase are selective and inhibit Eya2-mediated cell migration.

    PubMed

    Krueger, Aaron B; Drasin, David J; Lea, Wendy A; Patrick, Aaron N; Patnaik, Samarjit; Backos, Donald S; Matheson, Christopher J; Hu, Xin; Barnaeva, Elena; Holliday, Michael J; Blevins, Melanie A; Robin, Tyler P; Eisenmesser, Elan Z; Ferrer, Marc; Simeonov, Anton; Southall, Noel; Reigan, Philip; Marugan, Juan; Ford, Heide L; Zhao, Rui

    2014-06-01

    Eya proteins are essential co-activators of the Six family of transcription factors and contain a unique tyrosine phosphatase domain belonging to the haloacid dehalogenase family of phosphatases. The phosphatase activity of Eya is important for the transcription of a subset of Six1-target genes, and also directs cells to the repair rather than apoptosis pathway upon DNA damage. Furthermore, Eya phosphatase activity has been shown to mediate transformation, invasion, migration, and metastasis of breast cancer cells, making it a potential new drug target for breast cancer. We have previously identified a class of N-arylidenebenzohydrazide compounds that specifically inhibit the Eya2 phosphatase. Herein, we demonstrate that these compounds are reversible inhibitors that selectively inhibit the phosphatase activity of Eya2, but not Eya3. Our mutagenesis results suggest that this class of compounds does not bind to the active site and the binding does not require the coordination with Mg(2+). Moreover, these compounds likely bind within a site on the opposite face of the active site, and function as allosteric inhibitors. We also demonstrate that this class of compounds inhibits Eya2 phosphatase-mediated cell migration, setting the foundation for these molecules to be developed into chemical probes for understanding the specific function of the Eya2 phosphatase and to serve as a prototype for the development of Eya2 phosphatase specific anti-cancer drugs. PMID:24755226

  18. Catalytic and substrate promiscuity: distinct multiple chemistries catalysed by the phosphatase domain of receptor protein tyrosine phosphatase.

    PubMed

    Srinivasan, Bharath; Marks, Hanna; Mitra, Sreyoshi; Smalley, David M; Skolnick, Jeffrey

    2016-07-15

    The presence of latent activities in enzymes is posited to underlie the natural evolution of new catalytic functions. However, the prevalence and extent of such substrate and catalytic ambiguity in evolved enzymes is difficult to address experimentally given the order-of-magnitude difference in the activities for native and, sometimes, promiscuous substrate/s. Further, such latent functions are of special interest when the activities concerned do not fall into the domain of substrate promiscuity. In the present study, we show a special case of such latent enzyme activity by demonstrating the presence of two mechanistically distinct reactions catalysed by the catalytic domain of receptor protein tyrosine phosphatase isoform δ (PTPRδ). The primary catalytic activity involves the hydrolysis of a phosphomonoester bond (C─O─P) with high catalytic efficiency, whereas the secondary activity is the hydrolysis of a glycosidic bond (C─O─C) with poorer catalytic efficiency. This enzyme also displays substrate promiscuity by hydrolysing diester bonds while being highly discriminative for its monoester substrates. To confirm these activities, we also demonstrated their presence on the catalytic domain of protein tyrosine phosphatase Ω (PTPRΩ), a homologue of PTPRδ. Studies on the rate, metal-ion dependence, pH dependence and inhibition of the respective activities showed that they are markedly different. This is the first study that demonstrates a novel sugar hydrolase and diesterase activity for the phosphatase domain (PD) of PTPRδ and PTPRΩ. This work has significant implications for both understanding the evolution of enzymatic activity and the possible physiological role of this new chemistry. Our findings suggest that the genome might harbour a wealth of such alternative latent enzyme activities in the same protein domain that renders our knowledge of metabolic networks incomplete. PMID:27208174

  19. Prostatic acid phosphatase is the main acid phosphatase with 5'-ectonucleotidase activity in the male mouse saliva and regulates salivation.

    PubMed

    Araujo, César L; Quintero, Ileana B; Kipar, Anja; Herrala, Annakaisa M; Pulkka, Anitta E; Saarinen, Lilli; Hautaniemi, Sampsa; Vihko, Pirkko

    2014-06-01

    We have previously shown that in addition to the well-known secreted isoform of prostatic acid phosphatase (sPAP), a transmembrane isoform exists (TMPAP) that interacts with snapin (a SNARE-associated protein) and regulates the endo-/exocytic pathways. We have also shown that PAP has 5'-ectonucleotidase and thiamine monophosphatase activity and elicits antinociceptive effects in mouse models of chronic inflammatory and neuropathic pain. Therefore, to determine the physiological role of PAP in a typical exocrine organ, we studied the submandibular salivary gland (SMG) of PAP(-/-) and wild-type C57BL/6J mice by microarray analyses, microRNA sequencing, activity tests, immunohistochemistry, and biochemical and physiological analyses of saliva. We show that PAP is the main acid phosphatase in the wild-type male mouse saliva, accounting for 50% of the total acid phosphatase activity, and that it is expressed only in the granular convoluted tubules of the SMGs, where it is the only 5'-ectonucleotidase. The lack of PAP in male PAP(-/-) mice was associated with a significant increase in the salivation volume under secretagogue stimulation, overexpression of genes related to cell proliferation (Mki67, Aurkb, Birc5) and immune response (Irf7, Cxcl9, Ccl3, Fpr2), and upregulation of miR-146a in SMGs. An increased and sustained acinar cell proliferation was detected without signs of glandular hyperplasia. Our results indicate that in PAP(-/-) mice, SMG homeostasis is maintained by an innate immune response. Additionally, we suggest that in male mice, PAP via its 5'-ectonucleotidase activity and production of adenosine can elicit analgesic effects when animals lick their wounds. PMID:24717577

  20. Role of polynucleotide kinase/phosphatase in mitochondrial DNA repair

    PubMed Central

    Tahbaz, Nasser; Subedi, Sudip; Weinfeld, Michael

    2012-01-01

    Mutations in mitochondrial DNA (mtDNA) are implicated in a broad range of human diseases and in aging. Compared to nuclear DNA, mtDNA is more highly exposed to oxidative damage due to its proximity to the respiratory chain and the lack of protection afforded by chromatin-associated proteins. While repair of oxidative damage to the bases in mtDNA through the base excision repair pathway has been well studied, the repair of oxidatively induced strand breaks in mtDNA has been less thoroughly examined. Polynucleotide kinase/phosphatase (PNKP) processes strand-break termini to render them chemically compatible for the subsequent action of DNA polymerases and ligases. Here, we demonstrate that functionally active full-length PNKP is present in mitochondria as well as nuclei. Downregulation of PNKP results in an accumulation of strand breaks in mtDNA of hydrogen peroxide-treated cells. Full restoration of repair of the H2O2-induced strand breaks in mitochondria requires both the kinase and phosphatase activities of PNKP. We also demonstrate that PNKP contains a mitochondrial-targeting signal close to the C-terminus of the protein. We further show that PNKP associates with the mitochondrial protein mitofilin. Interaction with mitofilin may serve to translocate PNKP into mitochondria. PMID:22210862

  1. Par-4: A New Activator of Myosin Phosphatase

    PubMed Central

    Vetterkind, Susanne; Lee, Eunhee; Sundberg, Eric; Poythress, Ransom H.; Tao, Terence C.; Preuss, Ute

    2010-01-01

    Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis, and smooth muscle contractility. Although MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis response (Par)-4 modulates vascular smooth muscle contractility. Here, we test the hypothesis that Par-4 regulates MP activity directly. We show, by proximity ligation assays, surface plasmon resonance and coimmunoprecipitation, that Par-4 interacts with the targeting subunit of MP, MYPT1. Binding is mediated by the leucine zippers of MYPT1 and Par-4 and reduced by Par-4 phosphorylation. Overexpression of Par-4 leads to increased phosphatase activity of immunoprecipitated MP, whereas small interfering RNA knockdown of endogenous Par-4 significantly decreases MP activity and increases MYPT1 phosphorylation. LC20 phosphorylation assays demonstrate that overexpression of Par-4 reduces LC20 phosphorylation. In contrast, a phosphorylation site mutant, but not wild-type Par-4, interferes with zipper-interacting protein kinase (ZIPK)-mediated MP inhibition. We conclude from our results Par-4 operates through a “padlock” model in which binding of Par-4 to MYPT1 activates MP by blocking access to the inhibitory phosphorylation sites, and inhibitory phosphorylation of MYPT1 by ZIPK requires “unlocking” of Par-4 by phosphorylation and displacement of Par-4 from the MP complex. PMID:20130087

  2. Protein Phosphatase-1α Interacts with and Dephosphorylates Polycystin-1

    PubMed Central

    Parnell, Stephen C.; Puri, Sanjeev; Wallace, Darren P.; Calvet, James P.

    2012-01-01

    Polycystin signaling is likely to be regulated by phosphorylation. While a number of potential protein kinases and their target phosphorylation sites on polycystin-1 have been identified, the corresponding phosphatases have not been extensively studied. We have now determined that polycystin-1 is a regulatory subunit for protein phosphatase-1α (PP1α). Sequence analysis has revealed the presence of a highly conserved PP1-interaction motif in the cytosolic, C-terminal tail of polycystin-1; and we have shown that transfected PP1α specifically co-immunoprecipitates with a polycystin-1 C-tail construct. To determine whether PP1α dephosphorylates polycystin-1, a PKA-phosphorylated GST-polycystin-1 fusion protein was shown to be dephosphorylated by PP1α but not by PP2B (calcineurin). Mutations within the PP1-binding motif of polycystin-1, including an autosomal dominant polycystic kidney disease (ADPKD)-associated mutation, significantly reduced PP1α-mediated dephosphorylation of polycystin-1. The results suggest that polycystin-1 forms a holoenzyme complex with PP1α via a conserved PP1-binding motif within the polycystin-1 C-tail, and that PKA-phosphorylated polycystin-1 serves as a substrate for the holoenzyme. PMID:22675472

  3. Protein Phosphatase 1α Interacting Proteins in the Human Brain

    PubMed Central

    Esteves, Sara L.C.; Domingues, Sara C.; da Cruz e Silva, Odete A.B.; da Cruz e Silva, Edgar F.

    2012-01-01

    Abstract Protein Phosphatase 1 (PP1) is a major serine/threonine-phosphatase whose activity is dependent on its binding to regulatory subunits known as PP1 interacting proteins (PIPs), responsible for targeting PP1 to a specific cellular location, specifying its substrate or regulating its action. Today, more than 200 PIPs have been described involving PP1 in panoply of cellular mechanisms. Moreover, several PIPs have been identified that are tissue and event specific. In addition, the diversity of PP1/PIP complexes can further be achieved by the existence of several PP1 isoforms that can bind preferentially to a certain PIP. Thus, PP1/PIP complexes are highly specific for a particular function in the cell, and as such, they are excellent pharmacological targets. Hence, an in-depth survey was taken to identify specific PP1α PIPs in human brain by a high-throughput Yeast Two-Hybrid approach. Sixty-six proteins were recognized to bind PP1α, 39 being novel PIPs. A large protein interaction databases search was also performed to integrate with the results of the PP1α Human Brain Yeast Two-Hybrid and a total of 246 interactions were retrieved. PMID:22321011

  4. Functional Analysis of Protein Tyrosine Phosphatases in Thrombosis and Hemostasis.

    PubMed

    Rahmouni, Souad; Hego, Alexandre; Delierneux, Céline; Wéra, Odile; Musumeci, Lucia; Tautz, Lutz; Oury, Cécile

    2016-01-01

    Platelets are small blood cells derived from cytoplasmic fragments of megakaryocytes and play an essential role in thrombosis and hemostasis. Platelet activation depends on the rapid phosphorylation and dephosphorylation of key signaling molecules, and a number of kinases and phosphatases have been identified as major regulators of platelet function. However, the investigation of novel signaling proteins has suffered from technical limitations due to the anucleate nature of platelets and their very limited levels of mRNA and de novo protein synthesis. In the past, experimental methods were restricted to the generation of genetically modified mice and the development of specific antibodies. More recently, novel (phospho)proteomic technologies and pharmacological approaches using specific small-molecule inhibitors have added additional capabilities to investigate specific platelet proteins.In this chapter, we report methods for using genetic and pharmacological approaches to investigate the function of platelet signaling proteins. While the described experiments focus on the role of the dual-specificity phosphatase 3 (DUSP3) in platelet signaling, the presented methods are applicable to any signaling enzyme. Specifically, we describe a testing strategy that includes (1) aggregation and secretion experiments with mouse and human platelets, (2) immunoprecipitation and immunoblot assays to study platelet signaling events, (3) detailed protocols to use selected animal models in order to investigate thrombosis and hemostasis in vivo, and (4) strategies for utilizing pharmacological inhibitors on human platelets. PMID:27514813

  5. New functional aspects of the atypical protein tyrosine phosphatase VHZ

    PubMed Central

    Kuznetsov, Vyacheslav I.; Hengge, Alvan C.

    2013-01-01

    LDP3 (VHZ) is the smallest classical protein tyrosine phosphatase (PTP) known to date, and was originally misclassified as an atypical dual specificity phosphatase (DSP). Kinetic isotope effects with steady state and pre-steady state kinetics of VHZ and mutants with para-nitrophenol phosphate (pNPP) have revealed several unusual properties. VHZ is significantly more active than previously reported, but remains one of the least active PTPs. Highly unusual for a PTP, VHZ possesses two acidic residues (E134 and D65) in the active site. D65 occupies the position corresponding to the typical general acid in the PTP family. However, VHZ primarily utilizes E134 as the general acid, with D65 taking over this role when E134 is mutated. This unusual behavior is facilitated by two coexisting, but unequally populated, substrate binding modes. Unlike most classical PTPs, VHZ exhibits phosphotransferase activity. Despite the presence of the Q-loop that normally prevents alcoholysis of the phosphoenzyme intermediate in other classical PTPs, VHZ readily phosphorylates ethylene glycol. Although mutations to Q-loop residues affect this phosphotransferase activity, mutations on the IPD-loop that contains the general acid exert more control over this process. A single P68V substitution on this loop completely abolishes phosphotransferase activity. The ability of native VHZ to catalyze transphosphorylation may lead to an imbalance of intracellular phosphorylation, which could explain the correlation of its overexpression with several types of cancer. PMID:24073992

  6. Protein kinase and phosphatase activities of thylakoid membranes

    SciTech Connect

    Michel, H.; Shaw, E.K.; Bennett, J.

    1987-01-01

    Dephosphorylation of the 25 and 27 kDa light-harvesting Chl a/b proteins (LHCII) of the thylakoid membranes is catalyzed by a phosphatase which differs from previously reported thylakoid-bound phosphatases in having an alkaline pH optimum (9.0) and a requirement for Mg/sup 2 +/ ions. Dephosphorylation of the 8.3 kDa psb H gene product requires a Mg/sup 2 +/ ion concentration more than 200 fold higher than that for dephosphorylation of LHC II. The 8.3 kDa and 27 kDa proteins appear to be phosphorylated by two distinct kinases, which differ in substrate specificity and sensitivity to inhibitors. The plastoquinone antagonist 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone (DBMIB) inhibits phosphorylation of the 27 kDa LHC II much more readily than phosphorylation of the 8.3 kDa protein. A similar pattern of inhibition is seen for two synthetic oligopeptides (MRKSATTKKAVC and ATQTLESSSRC) which are analogs of the phosphorylation sites of the two proteins. Possible modes of action of DBMIB are discussed. 45 refs., 7 figs., 3 tabs.

  7. Ultrastructural localization of membrane phosphatases in teratocarcinoma and early embryos.

    PubMed Central

    Damjanov, I.; Cutler, L. S.; Solter, D.

    1977-01-01

    Ectodermal cells of the two- and three-germ layer-thick mouse egg-cylinders are considered to be the progenitors of embryonal carcinoma cells in embryo-derived teratocarcinomas. In an attempt to find differences between the tumor cells and equivalent embryonic cells, we have studied the electron microscopic cytochemical localization of alkaline phosphatase, 5'-nucleotidase, and Mg2+-activated adenosine triphosphatase (ATPase) in embryo-derived teratocarcinomas and mouse egg-cylinders. Alkaline phosphatase was detected in both embryonic and tumor cells, but its activity appeared much more intense in the tumor cells. No ATPase was demonstrated in embryonic ectodermal cells of 6-day-old embryos and only in occasional cells of 7- and 8-day-old embryos. No 5'-nucleotidase activity could be demonstrated in 6- to 8-day-old cylinders. There was marked ATPase and 5'-nucleotidase activity in the membranes of embryonal carcinoma cells. These data point out some differences on the plasma membrane between the embryonal carcinoma cells and equivalent embryonic cells. The potential significance of these differences is discussed with regards to the transformation of embryonic cells in tumor cells. (Am J Pathol 87:297-310, 1977). Images Figure 3 Figure 4 Figure 1 Figure 5 Figure 6 Figure 2 PMID:192083

  8. Functional Analysis of Dual-Specificity Protein Phosphatases in Angiogenesis.

    PubMed

    Amand, Mathieu; Erpicum, Charlotte; Gilles, Christine; Noël, Agnès; Rahmouni, Souad

    2016-01-01

    Therapeutic perspectives targeting angiogenesis in cancer stimulated an intense investigation of the mechanisms triggering and governing angiogenic processes. Several publications have highlighted the importance of typical dual-specificity phosphatases (DSPs) or MKPs in endothelial cells and their role in controlling different biological functions implicated in angiogenesis such as migration, proliferation, apoptosis, tubulogenesis, and cell adhesion. However, among atypical DSPs, the only one investigated in angiogenesis was DUSP3. We recently identified this DSP as a new key player in endothelial cells and angiogenesis. In this chapter we provide with detailed protocols and models used to investigate the role of DUSP3 in endothelial cells and angiogenesis. We start the chapter with an overview of the role of several DSPs in angiogenesis. We continue with providing a full description of a highly efficient transfection protocol to deplete DUSP3 using small interfering RNA (siRNA) in the primary human umbilical vein endothelial cells (HUVEC). We next describe the major assays used to investigate different processes involved in angiogenesis such as tube formation assay, proliferation assay and spheroids sprouting assay. We finish the chapter by validating our results in DUSP3-knockout mice using in vivo angiogenesis assays such as Matrigel plug and Lewis lung carcinoma cell subcutaneous xenograft model followed by anti-CD31 immunofluorescence and ex vivo aortic ring assay. All methods described can be adapted to other phosphatases and signaling molecules. PMID:27514814

  9. Protein phosphatase 1 suppresses androgen receptor ubiquitylation and degradation.

    PubMed

    Liu, Xiaming; Han, Weiwei; Gulla, Sarah; Simon, Nicholas I; Gao, Yanfei; Cai, Changmeng; Yang, Hongmei; Zhang, Xiaoping; Liu, Jihong; Balk, Steven P; Chen, Shaoyong

    2016-01-12

    The phosphoprotein phosphatases are emerging as important androgen receptor (AR) regulators in prostate cancer (PCa). We reported previously that the protein phosphatase 1 catalytic subunit (PP1α) can enhance AR activity by dephosphorylating a site in the AR hinge region (Ser650) and thereby decrease AR nuclear export. In this study we show that PP1α increases the expression of wildtype as well as an S650A mutant AR, indicating that it is acting through one or more additional mechanisms. We next show that PP1α binds primarily to the AR ligand binding domain and decreases its ubiquitylation and degradation. Moreover, we find that the PP1α inhibitor tautomycin increases phosphorylation of AR ubiquitin ligases including SKP2 and MDM2 at sites that enhance their activity, providing a mechanism by which PP1α may suppress AR degradation. Significantly, the tautomycin mediated decrease in AR expression was most pronounced at low androgen levels or in the presence of the AR antagonist enzalutamide. Consistent with this finding, the sensitivity of LNCaP and C4-2 PCa cells to tautomycin, as assessed by PSA synthesis and proliferation, was enhanced at low androgen levels or by treatment with enzalutamide. Together these results indicate that PP1α may contribute to stabilizing AR protein after androgen deprivation therapies, and that targeting PP1α or the AR-PP1α interaction may be effective in castration-resistant prostate cancer (CRPC). PMID:26636645

  10. The effect of vanadate on human kidney potassium dependent phosphatase.

    PubMed

    Nieder, G L; Corder, C N; Culp, P A

    1979-06-01

    This study examined the effects of vanadate on the potassium dependent phosphatase activity present in purified human kidney microsomal (Na+ + K+)-adenosine triphosphatase. Vanadate anion inhibited the K+-dependent phosphatase at a K1 of 35 nM. This inhibition was noncompetitive with the substrate, p-nitrophenylphosphate. The inhibition by vanadate at 1 mM K+ was only 45% of the inhibition that was observed at 10 mM K+. Neither preincubation of the enzyme with vanadate, nor changing the pH of the assay from 8.2 to 7.2 had any effect on the K1 for vanadate. The inclusion of 2.5 mM isoproterenol, to complex the yanadate, reversed the inhibition, as did diluting the enzymatic reaction. Vanadate also inhibited the overall (Na+ + K+)-ATPase reaction at a K1 of 1.91 microM. This inhibition was also reversible upon inclusion of isoproterenol in the assay. Increasing the level of magnesium from 6 mM to 30 mM lowered the K1 of vanadate to 0.25 microM. The possible role of vanadate as a physiological mediator of (Na+ + k+)-atpase activity is discussed. PMID:39261

  11. Plant species richness increases phosphatase activities in an experimental grassland

    NASA Astrophysics Data System (ADS)

    Hacker, Nina; Wilcke, Wolfgang; Oelmann, Yvonne

    2014-05-01

    Plant species richness has been shown to increase aboveground nutrient uptake requiring the mobilization of soil nutrient pools. For phosphorus (P) the underlying mechanisms for increased P release in soil under highly diverse grassland mixtures remain obscure because aboveground P storage and concentrations of inorganic and organic P in soil solution and differently reactive soil P pools are unrelated (Oelmann et al. 2011). The need of plants and soil microorganisms for P can increase the exudation of enzymes hydrolyzing organically bound P (phosphatases) which might represent an important release mechanism of inorganic P in a competitive environment such as highly diverse grassland mixtures. Our objectives were to test the effects of i) plant functional groups (legumes, grasses, non-leguminous tall and small herbs), and of (ii) plant species richness on microbial P (Pmic) and phosphatase activities in soil. In autumn 2013, we measured Pmic and alkaline phosphomonoesterase and phosphodiesterase activities in soil of 80 grassland mixtures comprising different community compositions and species richness (1, 2, 4, 8, 16, 60) in the Jena Experiment. In general, Pmic and enzyme activities were correlated (r = 0.59 and 0.46 for phosphomonoesterase and phosphodiesterase activities, respectively; p

  12. Human Prostatic Acid Phosphatase: Structure, Function and Regulation

    PubMed Central

    Muniyan, Sakthivel; Chaturvedi, Nagendra K.; Dwyer, Jennifer G.; LaGrange, Chad A.; Chaney, William G.; Lin, Ming-Fong

    2013-01-01

    Human prostatic acid phosphatase (PAcP) is a 100 kDa glycoprotein composed of two subunits. Recent advances demonstrate that cellular PAcP (cPAcP) functions as a protein tyrosine phosphatase by dephosphorylating ErbB-2/Neu/HER-2 at the phosphotyrosine residues in prostate cancer (PCa) cells, which results in reduced tumorigenicity. Further, the interaction of cPAcP and ErbB-2 regulates androgen sensitivity of PCa cells. Knockdown of cPAcP expression allows androgen-sensitive PCa cells to develop the castration-resistant phenotype, where cells proliferate under an androgen-reduced condition. Thus, cPAcP has a significant influence on PCa cell growth. Interestingly, promoter analysis suggests that PAcP expression can be regulated by NF-κB, via a novel binding sequence in an androgen-independent manner. Further understanding of PAcP function and regulation of expression will have a significant impact on understanding PCa progression and therapy. PMID:23698773

  13. The Problem of Defining Intelligence.

    ERIC Educational Resources Information Center

    Lubar, David

    1981-01-01

    The major philosophical issues surrounding the concept of intelligence are reviewed with respect to the problems surrounding the process of defining and developing artificial intelligence (AI) in computers. Various current definitions and problems with these definitions are presented. (MP)

  14. Alkaline Phosphatase, Soluble Extracellular Adenine Nucleotides, and Adenosine Production after Infant Cardiopulmonary Bypass

    PubMed Central

    Davidson, Jesse A.; Urban, Tracy; Tong, Suhong; Twite, Mark; Woodruff, Alan

    2016-01-01

    Rationale Decreased alkaline phosphatase activity after infant cardiac surgery is associated with increased post-operative cardiovascular support requirements. In adults undergoing coronary artery bypass grafting, alkaline phosphatase infusion may reduce inflammation. Mechanisms underlying these effects have not been explored but may include decreased conversion of extracellular adenine nucleotides to adenosine. Objectives 1) Evaluate the association between alkaline phosphatase activity and serum conversion of adenosine monophosphate to adenosine after infant cardiac surgery; 2) assess if inhibition/supplementation of serum alkaline phosphatase modulates this conversion. Methods and Research Pre/post-bypass serum samples were obtained from 75 infants <4 months of age. Serum conversion of 13C5-adenosine monophosphate to 13C5-adenosine was assessed with/without selective inhibition of alkaline phosphatase and CD73. Low and high concentration 13C5-adenosine monophosphate (simulating normal/stress concentrations) were used. Effects of alkaline phosphatase supplementation on adenosine monophosphate clearance were also assessed. Changes in serum alkaline phosphatase activity were strongly correlated with changes in 13C5-adenosine production with or without CD73 inhibition (r = 0.83; p<0.0001). Serum with low alkaline phosphatase activity (≤80 U/L) generated significantly less 13C5-adenosine, particularly in the presence of high concentration 13C5-adenosine monophosphate (10.4μmol/L vs 12.9μmol/L; p = 0.0004). Inhibition of alkaline phosphatase led to a marked decrease in 13C5-adenosine production (11.9μmol/L vs 2.7μmol/L; p<0.0001). Supplementation with physiologic dose human tissue non-specific alkaline phosphatase or high dose bovine intestinal alkaline phosphatase doubled 13C5-adenosine monophosphate conversion to 13C5-adenosine (p<0.0001). Conclusions Alkaline phosphatase represents the primary serum ectonucleotidase after infant cardiac surgery and low post

  15. Interactions of the HIV-1 Tat and RAP74 proteins with the RNA polymerase II CTD phosphatase FCP1.

    PubMed

    Abbott, Karen L; Archambault, Jacques; Xiao, Hua; Nguyen, Bao D; Roeder, Robert G; Greenblatt, Jack; Omichinski, James G; Legault, Pascale

    2005-03-01

    FCP1, a phosphatase specific for the carboxyl-terminal domain of the largest subunit of RNA polymerase II, is regulated by the HIV-1 Tat protein, CK2, TFIIB, and the large subunit of TFIIF (RAP74). We have characterized the interactions of Tat and RAP74 with the BRCT-containing central domain of FCP1 (FCP1(562)(-)(738)). We demonstrated that FCP1 is required for Tat-mediated transactivation in vitro and that amino acids 562-685 of FCP1 are necessary for Tat interaction in yeast two-hybrid studies. From sequence alignments, we identified a conserved acidic/hydrophobic region in FCP1 adjacent to its highly conserved BRCT domain. In vitro binding studies with purified proteins indicate that HIV-1 Tat interacts with both the acidic/hydrophobic region and the BRCT domain of FCP1, whereas RAP74(436)(-)(517) interacts solely with a portion of the acidic/hydrophobic region containing a conserved LXXLL-like motif. HIV-1 Tat inhibits the binding of RAP74(436)(-)(517) to FCP1. In a companion paper (K. Abbott et al. (2005) Enhanced Binding of RNAPII CTD Phosphatase FCP1 to RAP74 Following CK2 Phosphorylation, Biochemistry 44, 2732-2745, we identified a novel CK2 site adjacent to this conserved LXXLL-like motif. Phosphorylation of FCP1(562)(-)(619) by CK2 at this site increases binding to RAP74(436)(-)(517), but this phosphorylation is inhibited by Tat. Our results provide insights into the mechanisms by which Tat inhibits the FCP1 CTD phosphatase activity and by which FCP1 mediates transcriptional activation by Tat. In addition to increasing our understanding of the role of HIV-1 Tat in transcriptional regulation, this study defines a clear role for regions adjacent to the BRCT domain in promoting important protein-protein interactions. PMID:15723517

  16. Dephosphorylation of human insulin-like growth factor I (IGF-I) receptors by membrane-associated tyrosine phosphatases.

    PubMed Central

    Peraldi, P; Hauguel-de Mouzon, S; Alengrin, F; Van Obberghen, E

    1992-01-01

    The insulin-like growth factor-I (IGF-I) receptor exhibits structural and functional similarities to the insulin receptor. Although the regulation of the insulin-receptor tyrosine kinase has been extensively investigated, the mechanisms involved in phosphorylation/dephosphorylation of the IGF-I receptor have received only little attention. To obtain a better understanding of the mode of IGF-I action, we have investigated the effects of protein phosphotyrosine phosphatases (PTPases) on the phosphorylation status of the IGF-I receptor. The dephosphorylation of the human IGF-I receptor by membrane-associated tyrosine phosphatases was studied by an immuno-enzymic assay based on the recognition of phosphotyrosine residues by anti-phosphotyrosine antibodies. Using intact IGF-I receptors as substrates, we show that they could be completely dephosphorylated by different cellular PTPases. Three pieces of evidence indicate that receptor dephosphorylation takes place on phosphotyrosine, i.e. the inhibition profile of phosphatase activity by zinc and vanadate, its absolute requirement for thiol compounds and the diminution of [32P]phosphotyrosine labelling of the beta subunit assessed by SDS/PAGE and phosphoamino acid analysis. Tyrosine kinase activity and autophosphorylation of the IGF-I receptor were decreased in a dose-dependent manner by PTPases, indicating that partial dephosphorylation of the receptor was associated with a decrease in its intrinsic activity. The sensitivity of the activated human IGF-I receptor to dephosphorylation on tyrosine leads to the speculation that IGF-I receptor activity might be regulated by mechanisms such as those described for the insulin receptor. Further investigation of the pathways of IGF-I receptor dephosphorylation will contribute to define the role(s) of PTPases in the overall mechanism of IGF-I signalling. Images Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:1322128

  17. Structure and chromosomal localization of the human gene of the phosphotyrosyl phosphatase activator (PTPA) of protein phosphatase 2A

    SciTech Connect

    Van Hoof, C.; Cayla, X.; Merlevede, W.; Goris, J.

    1995-07-20

    The PTPA gene encodes a specific phosphotyrosyl phosphatase activator of the dimeric form of protein phosphatase 2A. PTPA, cloned from human genomic libraries, is encoded by one single-copy gene, composed of 10 exons and 9 introns with a total length of about 60 kb. The transcription start site was determined, and the 5{prime} flanking sequence was analyzed for its potential as a promotor. This region lacks a TATA sequence in the appropriate position relative to the transcription start, is very GC-rich, and contains upstream of the transcription start four Sp1 sites, a feature common to many TATA-less promotors. Based on the homology with DNA binding consensus sequences of transcription factors, we identified in this promotor region several putative DNA binding sites for transcription factors, such as NF-{kappa}B, Myb, Ets-1, Myc, and ATF. Transfection experiments with a construct containing the PTPA promotor region inserted 5{prime} of a luciferase reporter gene revealed that the 5{prime} flanking sequence of the PTPA gene indeed displayed promotor activity that seems to be cell-line dependent. By fluorescence in situ hybridization and G-banding, the PTPA gene was localized to the 9q34 region. The PTPA gene is positioned centromeric of c-abl in a region embracing several genes implicated in oncogenesis. 28 refs., 8 figs., 1 tab.

  18. Crystal structure of human dual specificity phosphatase, JNK stimulatory phosphatase-1, at 1.5 A resolution.

    PubMed

    Yokota, Takehiro; Nara, Yukinori; Kashima, Akiko; Matsubara, Keiko; Misawa, Satoru; Kato, Ryohei; Sugio, Shigetoshi

    2007-02-01

    Human JNK stimulatory phosphatase-1 (JSP-1) is a novel member of dual specificity phosphatases. A C-terminus truncated JSP-1 was expressed in Escherichia coli and was crystallized using the sitting-drop vapor diffusion method. Thin-plate crystals obtained at 278 K belong to a monoclinic space group, C2, with unit-cell parameters a = 84.0 A, b = 49.3 A, c = 47.3 A, and beta = 119.5 degrees , and diffract up to 1.5 A resolution at 100 K. The structure of JSP-1 has a single compact (alpha/beta) domain, which consists of six alpha-helices and five beta-strands, and shows a conserved structural scaffold in regard to both DSPs and PTPs. A cleft formed by a PTP-loop at the active site is very shallow, and is occupied by one sulfonate compound, MES, at the bottom. In the binary complex structure of JSP-1 with MES, the conformations of three important segments in regard to the catalytic mechanism are not similar to those in PTP1B. JSP-1 has no loop corresponding to the Lys120-loop of PTP1B, and tryptophan residue corresponding to the substrate-stacking in PTP1B is substituted by alanine residue in JSP-1. PMID:17068812

  19. Protein phosphatase 2A dysfunction in Alzheimer’s disease

    PubMed Central

    Sontag, Jean-Marie; Sontag, Estelle

    2014-01-01

    Protein phosphatase 2A (PP2A) is a large family of enzymes that account for the majority of brain Ser/Thr phosphatase activity. While PP2A enzymes collectively modulate most cellular processes, sophisticated regulatory mechanisms are ultimately responsible for ensuring isoform-specific substrate specificity. Of particular interest to the Alzheimer’s disease (AD) field, alterations in PP2A regulators and PP2A catalytic activity, subunit expression, methylation and/or phosphorylation, have been reported in AD-affected brain regions. “PP2A” dysfunction has been linked to tau hyperphosphorylation, amyloidogenesis and synaptic deficits that are pathological hallmarks of this neurodegenerative disorder. Deregulation of PP2A enzymes also affects the activity of many Ser/Thr protein kinases implicated in AD. This review will more specifically discuss the role of the PP2A/Bα holoenzyme and PP2A methylation in AD pathogenesis. The PP2A/Bα isoform binds to tau and is the primary tau phosphatase. Its deregulation correlates with increased tau phosphorylation in vivo and in AD. Disruption of PP2A/Bα-tau protein interactions likely contribute to tau deregulation in AD. Significantly, alterations in one-carbon metabolism that impair PP2A methylation are associated with increased risk for sporadic AD, and enhanced AD-like pathology in animal models. Experimental studies have linked deregulation of PP2A methylation with down-regulation of PP2A/Bα, enhanced phosphorylation of tau and amyloid precursor protein, tau mislocalization, microtubule destabilization and neuritic defects. While it remains unclear what are the primary events that underlie “PP2A” dysfunction in AD, deregulation of PP2A enzymes definitely affects key players in the pathogenic process. As such, there is growing interest in developing PP2A-centric therapies for AD, but this may be a daunting task without a better understanding of the regulation and function of specific PP2A enzymes. PMID:24653673

  20. Protein tyrosine and serine–threonine phosphatases in the sea urchin, Strongylocentrotus purpuratus: Identification and potential functions

    PubMed Central

    Byrum, C.A.; Walton, K.D.; Robertson, A.J.; Carbonneau, S.; Thomason, R.T.; Coffman, J.A.; McClay, D.R.

    2011-01-01

    Protein phosphatases, in coordination with protein kinases, play crucial roles in regulation of signaling pathways. To identify protein tyrosine phosphatases (PTPs) and serine–threonine (ser–thr) phosphatases in the Strongylocentrotus purpuratus genome, 179 annotated sequences were studied (122 PTPs, 57 ser–thr phosphatases). Sequence analysis identified 91 phosphatases (33 conventional PTPs, 31 dual specificity phosphatases, 1 Class III Cysteine-based PTP, 1 Asp-based PTP, and 25 ser–thr phosphatases). Using catalytic sites, levels of conservation and constraint in amino acid sequence were examined. Nine of 25 receptor PTPs (RPTPs) corresponded to human, nematode, or fly homologues. Domain structure revealed that sea urchin-specific RPTPs including two, PTPRLec and PTPRscav, may act in immune defense. Embryonic transcription of each phosphatase was recorded from a high-density oligonucleotide tiling microarray experiment. Most RPTPs are expressed at very low levels, whereas nonreceptor PTPs (NRPTPs) are generally expressed at moderate levels. High expression was detected in MAP kinase phosphatases (MKPs) and numerous ser–thr phosphatases. For several expressed NRPTPs, MKPs, and ser–thr phosphatases, morpholino antisense-mediated knockdowns were performed and phenotypes obtained. Finally, to assess roles of annotated phosphatases in endomesoderm formation, a literature review of phosphatase functions in model organisms was superimposed on sea urchin developmental pathways to predict areas of functional activity. PMID:17087928

  1. Sac2/INPP5F is an inositol 4-phosphatase that functions in the endocytic pathway

    PubMed Central

    Nakatsu, Fubito; Messa, Mirko; Nández, Ramiro; Czapla, Heather; Zou, Yixiao; Strittmatter, Stephen M.

    2015-01-01

    The recruitment of inositol phosphatases to endocytic membranes mediates dephosphorylation of PI(4,5)P2, a phosphoinositide concentrated in the plasma membrane, and prevents its accumulation on endosomes. The importance of the conversion of PI(4,5)P2 to PtdIns during endocytosis is demonstrated by the presence of both a 5-phosphatase and a 4-phosphatase (Sac domain) module in the synaptojanins, endocytic PI(4,5)P2 phosphatases conserved from yeast to humans and the only PI(4,5)P2 phosphatases in yeast. OCRL, another 5-phosphatase that couples endocytosis to PI(4,5)P2 dephosphorylation, lacks a Sac domain. Here we show that Sac2/INPP5F is a PI4P phosphatase that colocalizes with OCRL on endocytic membranes, including vesicles formed by clathrin-mediated endocytosis, macropinosomes, and Rab5 endosomes. An OCRL–Sac2/INPP5F interaction could be demonstrated by coimmunoprecipitation and was potentiated by Rab5, whose activity is required to recruit Sac2/INPP5F to endosomes. Sac2/INPP5F and OCRL may cooperate in the sequential dephosphorylation of PI(4,5)P2 at the 5 and 4 position of inositol in a partnership that mimics that of the two phosphatase modules of synaptojanin. PMID:25869668

  2. Fluorescence labelling of phosphatase activity in digestive glands of carnivorous plants.

    PubMed

    Płachno, B J; Adamec, L; Lichtscheidl, I K; Peroutka, M; Adlassnig, W; Vrba, J

    2006-11-01

    A new ELF (enzyme labelled fluorescence) assay was applied to detect phosphatase activity in glandular structures of 47 carnivorous plant species, especially Lentibulariaceae, in order to understand their digestive activities. We address the following questions: (1) Are phosphatases produced by the plants and/or by inhabitants of the traps? (2) Which type of hairs/glands is involved in the production of phosphatases? (3) Is this phosphatase production a common feature among carnivorous plants or is it restricted to evolutionarily advanced species? Our results showed activity of the phosphatases in glandular structures of the majority of the plants tested, both from the greenhouse and from sterile culture. In addition, extracellular phosphatases can also be produced by trap inhabitants. In Utricularia, activity of phosphatase was detected in internal glands of 27 species from both primitive and advanced sections and different ecological groups. Further positive reactions were found in Genlisea, Pinguicula, Aldrovanda, Dionaea, Drosera, Drosophyllum, Nepenthes, and Cephalotus. In Utricularia and Genlisea, enzymatic secretion was independent of stimulation by prey. Byblis and Roridula are usually considered as "proto-carnivores", lacking digestive enzymes. However, we found high activity of phosphatases in both species. Thus, they should be classified as true carnivores. We suggest that the inflorescence of Byblis and some Pinguicula species might also be an additional "carnivorous organ", which can trap a prey, digest it, and finally absorb available nutrients. PMID:16865659

  3. Enhancing Potato System Sustainability: Crop Rotation Impacts on Soil Phosphatase Activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato is a species with a low efficiency of acquiring soil P. Rotation crops may potentially influence P uptake by potato by increasing soil organic acids, phosphatase activity, and microbial biomass. However, this kind of information is very limited. We measured the activities of acid phosphatase,...

  4. Okadaic acid-sensitive protein phosphatases constrain phrenic long-term facilitation after sustained hypoxia.

    PubMed

    Wilkerson, Julia E R; Satriotomo, Irawan; Baker-Herman, Tracy L; Watters, Jyoti J; Mitchell, Gordon S

    2008-03-12

    Phrenic long-term facilitation (pLTF) is a serotonin-dependent form of pattern-sensitive respiratory plasticity induced by intermittent hypoxia (IH), but not sustained hypoxia (SH). The mechanism(s) underlying pLTF pattern sensitivity are unknown. SH and IH may differentially regulate serine/threonine protein phosphatase activity, thereby inhibiting relevant protein phosphatases uniquely during IH and conferring pattern sensitivity to pLTF. We hypothesized that spinal protein phosphatase inhibition would relieve this braking action of protein phosphatases, thereby revealing pLTF after SH. Anesthetized rats received intrathecal (C4) okadaic acid (25 nm) before SH (25 min, 11% O(2)). Unlike (vehicle) control rats, SH induced a significant pLTF in okadaic acid-treated rats that was indistinguishable from rats exposed to IH (three 5 min episodes, 11% O(2)). IH and SH with okadaic acid may elicit pLTF by similar, serotonin-dependent mechanisms, because intravenous methysergide blocks pLTF in rats receiving IH or okadaic acid plus SH. Okadaic acid did not alter IH-induced pLTF. In summary, pattern sensitivity in pLTF may reflect differential regulation of okadaic acid-sensitive serine/threonine phosphatases; presumably, these phosphatases are less active during/after IH versus SH. The specific okadaic acid-sensitive phosphatase(s) constraining pLTF and their spatiotemporal dynamics during and/or after IH and SH remain to be determined. PMID:18337426

  5. Relationship between phosphorus forms and phosphatase activity in soils amended with poultry manure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Up to 80% of the phosphorus (P) in poultry manure (PM) can be present in organic forms that require mineralization via phosphatase enzymes prior to plant utilization. To determine the correlation between soil P distribution and phosphatase activity we sequentially extracted two Maine soils amended...

  6. Intramolecular dynamics of structure of alkaline phosphatase from Escherichia coli

    NASA Astrophysics Data System (ADS)

    Mazhul, Vladimir M.; Mjakinnik, Igor V.; Volkova, Alena N.

    1995-01-01

    The luminescent analysis with nano- and millisecond time resolution of intramolecular dynamics of Escherichia coli alkaline phosphatase was carried out. The effect of pH within the range 7.2 - 9.0, thermal inactivation, limited proteolysis by trypsin, binding of pyrophosphate, interconversion of enzyme and apoenzyme, the replacement of Zn2+ and Mg2+ in the active site by Cd2+ and Ni2+ on the spectral and kinetic parameters of luminescence was investigated. The essential changes of the level of nano- and millisecond dynamics of protein structure were found to correlate with the shift of enzymatic activity. The importance of small- and large-scale flexibility of protein structure for the act of enzymatic catalysis realization was shown.

  7. The influence of complexing pharmaceutical compositions on alkaline phosphatase

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Chukhrai, E. S.; Stepina, N. D.; Novikova, N. N.; Yur'eva, E. A.

    2011-06-01

    It is established that the pharmaceutical compositions xydiphon, medifon, succimer, and EDTA, which are used as complexing agents for accelerating the excretion of heavy metals from human organism, at certain concentrations inhibit enzyme alkaline phosphatase (AP). It is concluded that xydiphon and EDTA have a noticeable effect on AP activity at concentrations over 0.01 mM; medifon and succimer, at concentrations of over 0.3-0.5 mM. The enzyme's inhibition constants and type of inhibition are determined. Xydiphon is found to manifest the highest affinity to AP ( K I = 0.35 mM). It is shown by kinetic analysis that dissociative chemoinactivation of the enzyme takes place under the action of complexing agents. The corresponding kinetic parameters are calculated.

  8. Establishing Quantitative Standards for Residual Alkaline Phosphatase in Pasteurized Milk.

    PubMed

    Kim, Dong-Hyeon; Chon, Jung-Whan; Lim, Jong-Soo; Kim, Hong-Seok; Kang, Il-Byeong; Jeong, Dana; Song, Kwang-Young; Kim, Hyunsook; Kim, Kwang-Yup; Seo, Kun-Ho

    2016-01-01

    The alkaline phosphatase (ALP) assay is a rapid and convenient method for verifying milk pasteurization. Since colorimetric ALP assays rely on subjective visual assessments, their results are especially unreliable near the detection limits. In this study, we attempted to establish quantitative criteria for residual ALP in milk by using a more objective method based on spectrophotometric measurements. Raw milk was heat-treated for 0, 10, 20, 30, and 40 min and then subjected to ALP assays. The quantitative criteria for residual ALP in the milk was determined as 2 μg phenol/mL of milk, which is just above the ALP value of milk samples heat-treated for 30 min. These newly proposed methodology and criteria could facilitate the microbiological quality control of milk. PMID:27194927

  9. Alkaline phosphatase activity in normal and inflamed dental pulps.

    PubMed

    Spoto, G; Fioroni, M; Rubini, C; Tripodi, D; Di Stilio, M; Piattelli, A

    2001-03-01

    Alkaline phosphatase (ALP) seems to be important in the formation of mineralized tissues. High levels of ALP have been demonstrated in dental pulp cells. In the present study ALP activity was analyzed in normal healthy human dental pulps, in reversible pulpitis, and in irreversible pulpitis. Enzymatic ALP control values for the normal healthy pulps were 110.96+/-20.93. In the reversible pulpitis specimens the ALP activity increased almost eight times to 853.6+/-148.27. In the irreversible pulpitis specimens the values decreased sharply to 137.15+/-21.28 and were roughly equivalent to those seen in normal healthy pulps. The differences between the groups (control vs. reversible pulpitis and reversible pulpitis vs. irreversible pulpitis) were statistically significant. These results could point to a role of ALP in the initial pulp response after injury. PMID:11487147

  10. Protein-Tyrosine Phosphatase 1B Substrates and Metabolic Regulation

    PubMed Central

    Bakke, Jesse; Haj, Fawaz G.

    2014-01-01

    Metabolic homeostasis requires integration of complex signaling networks which, when deregulated, contribute to metabolic syndrome and related disorders. Protein-tyrosine phosphatase 1B (PTP1B) has emerged as a key regulator of signaling networks that are implicated in metabolic diseases such as obesity and type 2 diabetes. In this review, we examine mechanisms that regulate PTP1B-substrate interaction, enzymatic activity and experimental approaches to identify PTP1B substrates. We then highlight findings that implicate PTP1B in metabolic regulation. In particular, insulin and leptin signaling are discussed as well as recently identified PTP1B substrates that are involved in endoplasmic reticulum stress response, cell-cell communication, energy balance and vesicle trafficking. In summary, PTP1B exhibits exquisite substrate specificity and is an outstanding pharmaceutical target for obesity and type 2 diabetes. PMID:25263014

  11. Methods to monitor classical protein-tyrosine phosphatase oxidation

    PubMed Central

    Karisch, Robert; Neel, Benjamin G.

    2012-01-01

    SUMMARY Reactive oxygen species (ROS), particularly H2O2, act as intracellular second messengers in many signaling pathways. Protein-tyrosine phosphatases (PTPs) are now believed to be important targets of ROS. PTPs contain a conserved catalytic cysteine with an unusually low pKa. This property allows PTPs to execute nucleophilic attack on substrate phosphotyrosyl residues, but also renders them highly susceptible to oxidation. Reversible oxidation, which inactivates PTPs, is emerging as an important cellular regulatory mechanism and might contribute to human diseases, including cancer. Given their potential toxicity, it seems likely that ROS generation is highly controlled within cells to restrict oxidation to those PTPs that must be inactivated for signaling to proceed. Thus, identifying ROS-inactivated PTPs could be tantamount to finding the PTP(s) that critically regulate a specific signaling pathway. This article provides an overview of the methods currently available to identify and quantify PTP oxidation and outlines future challenges in redox signaling. PMID:22577968

  12. The effect of sorbitol on acid phosphatase deactivation.

    PubMed

    Gianfreda, L; Toscano, G; Pirozzi, D; Greco, G

    1991-12-01

    Acid phosphatase thermal deactivation follows a complex path: an initial decay toward an equilibrium distribution of at least two intermediate structures, mutually at the equilibrium, followed by a final breakdown toward a completely inactive enzyme configuration. The results obtained in the presence of sorbitol have been compared to those produced in the course of purely thermal deactivation of the native enzyme. For any sobitol concentration, an equivalent temperature is calculated that results in exactly the same activity-versus-time profile. This suggests enzyme deactivation to be controlled by a single, unchanging step. Immobilized enzyme runs have been performed, as well, by entrapping acid phosphates within a polymeric network formed onto the upstream surface of an ultrafiltration membrane. The stabilizing effect of entrapment cumulates with that produced by sorbitol. In this case, however, an equivalent temperature cannot be determined, thus indicating that a different deactivation mechanism is followed. PMID:18600710

  13. Establishing Quantitative Standards for Residual Alkaline Phosphatase in Pasteurized Milk

    PubMed Central

    Chon, Jung-Whan; Kim, Hyunsook; Kim, Kwang-Yup

    2016-01-01

    The alkaline phosphatase (ALP) assay is a rapid and convenient method for verifying milk pasteurization. Since colorimetric ALP assays rely on subjective visual assessments, their results are especially unreliable near the detection limits. In this study, we attempted to establish quantitative criteria for residual ALP in milk by using a more objective method based on spectrophotometric measurements. Raw milk was heat-treated for 0, 10, 20, 30, and 40 min and then subjected to ALP assays. The quantitative criteria for residual ALP in the milk was determined as 2 μg phenol/mL of milk, which is just above the ALP value of milk samples heat-treated for 30 min. These newly proposed methodology and criteria could facilitate the microbiological quality control of milk. PMID:27194927

  14. Follow-up on the Berg acid phosphatase test.

    PubMed

    Schiff, A F

    1998-03-01

    Approximately 42 years ago, the Berg acid phosphatase (AP) test (1) was accepted in most rape treatment centers nationally as the standard to determine whether sexual intercourse or related actions in any form had occurred. More specifically, the test was designed to determine the presence of a certain enzyme. In October 1969, I published an article making the test simpler (2) and reviewing the history of various tests for the detection of AP, an enzyme found in great abundance in seminal fluid. Both AP-impregnated material and refrigerated reagents had been saved along with a quantity of seminal fluid used in the original tests. The objectives of this study were to determine whether 25-year-old seminal fluid in any form can still be identified by the AP test and whether 25-year-old chemicals have remained stable and are still usable. PMID:9539395

  15. Covalent Docking Predicts Substrates for Haloalkanoate Dehalogenase Superfamily Phosphatases

    PubMed Central

    2015-01-01

    Enzyme function prediction remains an important open problem. Though structure-based modeling, such as metabolite docking, can identify substrates of some enzymes, it is ill-suited to reactions that progress through a covalent intermediate. Here we investigated the ability of covalent docking to identify substrates that pass through such a covalent intermediate, focusing particularly on the haloalkanoate dehalogenase superfamily. In retrospective assessments, covalent docking recapitulated substrate binding modes of known cocrystal structures and identified experimental substrates from a set of putative phosphorylated metabolites. In comparison, noncovalent docking of high-energy intermediates yielded nonproductive poses. In prospective predictions against seven enzymes, a substrate was identified for five. For one of those cases, a covalent docking prediction, confirmed by empirical screening, and combined with genomic context analysis, suggested the identity of the enzyme that catalyzes the orphan phosphatase reaction in the riboflavin biosynthetic pathway of Bacteroides. PMID:25513739

  16. Lack of relationship between activity of intestinal alkaline phosphatase and calcium or phosphate absorption.

    PubMed

    Asteggiano, C; Tolosa, N; Pereira, R; Moreno, J; Cañas, F

    1981-01-01

    The effects of vitamin D3 and the aqueous extract of Solanum malacoxylon on intestinal alkaline phosphatase and tissue phosphate content were studied on rachitic chicks treated with large doses of ethane-1-hydroxy-1,1 diphosphonate (EHDP). The EHDP treatment blocks the increase of intestinal calcium or phosphate absorption induced by the vitamin D3, while it has no effects on the rise of intestinal alkaline phosphatase activity or the increment in tissue phosphate content. The lack of correlation between the increment of alkaline phosphatase and that of Ca or phosphate absorption in vitamin D3 plus EHDP treated chicks excludes a participation of the alkaline phosphatase in the mechanism of Ca or P intestinal absorption. The Ca or phosphorus absorption are elicited specifically by 1,25-(OH)2-D3, while alkaline phosphatase activity and phosphate tissue concentration respond to a broader spectrum of stimuli. PMID:6316731

  17. The involvement of glucose-6-phosphatase in mucilage secretion by root cap cells of Zea mays

    NASA Technical Reports Server (NTRS)

    Moore, R.; McClelen, C. E.

    1985-01-01

    In order to determine the involvement of glucose-6-phosphatase in mucilage secretion by root cap cells, we have cytochemically localized the enzyme in columella and peripheral cells of root caps of Zea mays. Glucose-6-phosphatase is associated with the plasmalemma and cell wall of columella cells. As columella cells differentiate into peripheral cells and begin to produce and secrete mucilage, glucose-6-phosphatase staining intensifies and becomes associated with the mucilage and, to a lesser extent, the cell wall. Cells being sloughed from the cap are characterized by glucose-6-phosphatase staining being associated with the vacuole and plasmalemma. These changes in enzyme localization during cellular differentiation in root caps suggest that glucose-6-phosphatase is involved in the production and/or secretion of mucilage by peripheral cells of Z. mays.

  18. Mannitol metabolism in brown algae involves a new phosphatase family.

    PubMed

    Groisillier, Agnès; Shao, Zhanru; Michel, Gurvan; Goulitquer, Sophie; Bonin, Patricia; Krahulec, Stefan; Nidetzky, Bernd; Duan, Delin; Boyen, Catherine; Tonon, Thierry

    2014-02-01

    Brown algae belong to a phylogenetic lineage distantly related to green plants and animals, and are found predominantly in the intertidal zone, a harsh and frequently changing environment. Because of their unique evolutionary history and of their habitat, brown algae feature several peculiarities in their metabolism. One of these is the mannitol cycle, which plays a central role in their physiology, as mannitol acts as carbon storage, osmoprotectant, and antioxidant. This polyol is derived directly from the photoassimilate fructose-6-phosphate via the action of a mannitol-1-phosphate dehydrogenase and a mannitol-1-phosphatase (M1Pase). Genome analysis of the brown algal model Ectocarpus siliculosus allowed identification of genes potentially involved in the mannitol cycle. Among these, two genes coding for haloacid dehalogenase (HAD)-like enzymes were suggested to correspond to M1Pase activity, and thus were named EsM1Pase1 and EsM1Pase2, respectively. To test this hypothesis, both genes were expressed in Escherichia coli. Recombinant EsM1Pase2 was shown to hydrolyse the phosphate group from mannitol-1-phosphate to produce mannitol but was not active on the hexose monophosphates tested. Gene expression analysis showed that transcription of both E. siliculosus genes was under the influence of the diurnal cycle. Sequence analysis and three-dimensional homology modelling indicated that EsM1Pases, and their orthologues in Prasinophytes, should be seen as founding members of a new family of phosphatase with original substrate specificity within the HAD superfamily of proteins. This is the first report describing the characterization of a gene encoding M1Pase activity in photosynthetic organisms. PMID:24323504

  19. Pten (phosphatase and tensin homologue gene) haploinsufficiency promotes insulin hypersensitivity

    PubMed Central

    Wong, J. T.; Kim, P. T. W.; Peacock, J. W.; Yau, T. Y.; Mui, A. L.-F.; Chung, S. W.; Sossi, V.; Doudet, D.; Green, D.; Ruth, T. J.; Parsons, R.; Verchere, C. B.

    2006-01-01

    Aims/hypothesis Insulin controls glucose metabolism via multiple signalling pathways, including the phosphatidylinositol 3-kinase (PI3K) pathway in muscle and adipose tissue. The protein/lipid phosphatase Pten (phosphatase and tensin homologue deleted on chromosome 10) attenuates PI3K signalling by dephosphorylating the phosphatidylinositol 3,4,5-trisphosphate generated by PI3K. The current study was aimed at investigating the effect of haploinsufficiency for Pten on insulin-stimulated glucose uptake. Materials and methods Insulin sensitivity in Pten heterozygous (Pten+/−) mice was investigated in i.p. insulin challenge and glucose tolerance tests. Glucose uptake was monitored in vitro in primary cultures of myocytes from Pten+/− mice, and in vivo by positron emission tomography. The phosphorylation status of protein kinase B (PKB/Akt), a downstream signalling protein in the PI3K pathway, and glycogen synthase kinase 3β (GSK3β), a substrate of PKB/Akt, was determined by western immunoblotting. Results Following i.p. insulin challenge, blood glucose levels in Pten+/− mice remained depressed for up to 120 min, whereas glucose levels in wild-type mice began to recover after approximately 30 min. After glucose challenge, blood glucose returned to normal about twice as rapidly in Pten+/− mice. Enhanced glucose uptake was observed both in Pten+/− myocytes and in skeletal muscle of Pten+/− mice by PET. PKB and GSK3β phosphorylation was enhanced and prolonged in Pten+/− myocytes. Conclusions/interpretation Pten is a key negative regulator of insulin-stimulated glucose uptake in vitro and in vivo. The partial reduction of Pten due to Pten haploinsufficiency is enough to elicit enhanced insulin sensitivity and glucose tolerance in Pten+/− mice. PMID:17195063

  20. Hyperphosphatemia, Phosphoprotein Phosphatases, and Microparticle Release in Vascular Endothelial Cells

    PubMed Central

    Abbasian, Nima; Burton, James O.; Herbert, Karl E.; Tregunna, Barbara-Emily; Brown, Jeremy R.; Ghaderi-Najafabadi, Maryam; Brunskill, Nigel J.; Goodall, Alison H.

    2015-01-01

    Hyperphosphatemia in patients with advanced CKD is thought to be an important contributor to cardiovascular risk, in part because of endothelial cell (EC) dysfunction induced by inorganic phosphate (Pi). Such patients also have an elevated circulating concentration of procoagulant endothelial microparticles (MPs), leading to a prothrombotic state, which may contribute to acute occlusive events. We hypothesized that hyperphosphatemia leads to MP formation from ECs through an elevation of intracellular Pi concentration, which directly inhibits phosphoprotein phosphatases, triggering a global increase in phosphorylation and cytoskeletal changes. In cultured human ECs (EAhy926), incubation with elevated extracellular Pi (2.5 mM) led to a rise in intracellular Pi concentration within 90 minutes. This was mediated by PiT1/slc20a1 Pi transporters and led to global accumulation of tyrosine- and serine/threonine-phosphorylated proteins, a marked increase in cellular Tropomyosin-3, plasma membrane blebbing, and release of 0.1- to 1-μm-diameter MPs. The effect of Pi was independent of oxidative stress or apoptosis. Similarly, global inhibition of phosphoprotein phosphatases with orthovanadate or fluoride yielded a global protein phosphorylation response and rapid release of MPs. The Pi-induced MPs expressed VE-cadherin and superficial phosphatidylserine, and in a thrombin generation assay, they displayed significantly more procoagulant activity than particles derived from cells incubated in medium with a physiologic level of Pi (1 mM). These data show a mechanism of Pi-induced cellular stress and signaling, which may be widely applicable in mammalian cells, and in ECs, it provides a novel pathologic link between hyperphosphatemia, generation of MPs, and thrombotic risk. PMID:25745026

  1. Hyperphosphatemia, Phosphoprotein Phosphatases, and Microparticle Release in Vascular Endothelial Cells.

    PubMed

    Abbasian, Nima; Burton, James O; Herbert, Karl E; Tregunna, Barbara-Emily; Brown, Jeremy R; Ghaderi-Najafabadi, Maryam; Brunskill, Nigel J; Goodall, Alison H; Bevington, Alan

    2015-09-01

    Hyperphosphatemia in patients with advanced CKD is thought to be an important contributor to cardiovascular risk, in part because of endothelial cell (EC) dysfunction induced by inorganic phosphate (Pi). Such patients also have an elevated circulating concentration of procoagulant endothelial microparticles (MPs), leading to a prothrombotic state, which may contribute to acute occlusive events. We hypothesized that hyperphosphatemia leads to MP formation from ECs through an elevation of intracellular Pi concentration, which directly inhibits phosphoprotein phosphatases, triggering a global increase in phosphorylation and cytoskeletal changes. In cultured human ECs (EAhy926), incubation with elevated extracellular Pi (2.5 mM) led to a rise in intracellular Pi concentration within 90 minutes. This was mediated by PiT1/slc20a1 Pi transporters and led to global accumulation of tyrosine- and serine/threonine-phosphorylated proteins, a marked increase in cellular Tropomyosin-3, plasma membrane blebbing, and release of 0.1- to 1-μm-diameter MPs. The effect of Pi was independent of oxidative stress or apoptosis. Similarly, global inhibition of phosphoprotein phosphatases with orthovanadate or fluoride yielded a global protein phosphorylation response and rapid release of MPs. The Pi-induced MPs expressed VE-cadherin and superficial phosphatidylserine, and in a thrombin generation assay, they displayed significantly more procoagulant activity than particles derived from cells incubated in medium with a physiologic level of Pi (1 mM). These data show a mechanism of Pi-induced cellular stress and signaling, which may be widely applicable in mammalian cells, and in ECs, it provides a novel pathologic link between hyperphosphatemia, generation of MPs, and thrombotic risk. PMID:25745026

  2. Identification and enzymatic characterization of acid phosphatase from Burkholderia gladioli

    PubMed Central

    2014-01-01

    Background The genus Burkholderia is widespread in diverse ecological niches, the majority of known species are soil bacteria that exhibit different types of non-pathogenic interactions with plants. Burkholderia species are versatile organisms that solubilize insoluble minerals through the production of organic acids, which increase the availability of nutrients for the plant. Therefore these bacteria are promising candidates for biotechnological applications. Results Burkholderia sp. (R 3.25 isolate) was isolated from agricultural soil in Ponta Grossa-PR-Brazil and identified through analysis of the 16S rDNA as a strain classified as Burkholderia gladioli. The expression of membrane-bound acid phosphatase (MBAcP) was strictly regulated with optimal expression at a concentration of phosphorus 5 mM. The apparent optimum pH for the hydrolysis of p-nitrophenylphosphate (PNPP) was 6.0. The hydrolysis of PNPP by the enzyme exhibited a hyperbolic relationship with increasing concentration of substrate and no inhibition by excess of substrate was observed. Kinetic data revealed that the hydrolysis of PNPP exhibited cooperative kinetics with n = 1.3, Vm = 113.5 U/mg and K0.5 = 65 μM. The PNPPase activity was inhibited by vanadate, p-hydroxymercuribenzoate, arsenate and phosphate, however the activity was not inhibited by calcium, levamisole, sodium tartrate, EDTA, zinc, magnesium, cobalt, ouabain, oligomycin or pantoprazol. Conclusion The synthesis of membrane-bound non-specific acid phosphatase, strictly regulated by phosphate, and its properties suggest that this bacterium has a potential biotechnological application to solubilize phosphate in soils with low levels of this element, for specific crops. PMID:24713147

  3. Frequent mutation of receptor protein tyrosine phosphatases provides a mechanism for STAT3 hyperactivation in head and neck cancer

    PubMed Central

    Lui, Vivian Wai Yan; Peyser, Noah D.; Ng, Patrick Kwok-Shing; Hritz, Jozef; Zeng, Yan; Lu, Yiling; Li, Hua; Wang, Lin; Gilbert, Breean R.; General, Ignacio J.; Bahar, Ivet; Ju, Zhenlin; Wang, Zhenghe; Pendleton, Kelsey P.; Xiao, Xiao; Du, Yu; Vries, John K.; Hammerman, Peter S.; Garraway, Levi A.; Mills, Gordon B.; Johnson, Daniel E.; Grandis, Jennifer R.

    2014-01-01

    The underpinnings of STAT3 hyperphosphorylation resulting in enhanced signaling and cancer progression are incompletely understood. Loss-of-function mutations of enzymes that dephosphorylate STAT3, such as receptor protein tyrosine phosphatases, which are encoded by the PTPR gene family, represent a plausible mechanism of STAT3 hyperactivation. We analyzed whole exome sequencing (n = 374) and reverse-phase protein array data (n = 212) from head and neck squamous cell carcinomas (HNSCCs). PTPR mutations are most common and are associated with significantly increased phospho-STAT3 expression in HNSCC tumors. Expression of receptor-like protein tyrosine phosphatase T (PTPRT) mutant proteins induces STAT3 phosphorylation and cell survival, consistent with a “driver” phenotype. Computational modeling reveals functional consequences of PTPRT mutations on phospho-tyrosine–substrate interactions. A high mutation rate (30%) of PTPRs was found in HNSCC and 14 other solid tumors, suggesting that PTPR alterations, in particular PTPRT mutations, may define a subset of patients where STAT3 pathway inhibitors hold particular promise as effective therapeutic agents. PMID:24395800

  4. Kidney bone disease and mortality in CKD: revisiting the role of vitamin D, calcimimetics, alkaline phosphatase, and minerals.

    PubMed

    Kalantar-Zadeh, Kamyar; Shah, Anuja; Duong, Uyen; Hechter, Rulin C; Dukkipati, Ramanath; Kovesdy, Csaba P

    2010-08-01

    Recent evidence suggests that the traditional syndromes known as renal osteodystrophy, secondary hyperparathyroidism, and vitamin D deficiency are related to mortality in persons with moderate to advanced chronic kidney disease (CKD). The so-called 'kidney bone disease', also known as 'mineral and bone disorders', is defined to include bone disorders, mineral disarrays, and vascular calcification. We have identified 14 common and clinically relevant conditions of contemporary nature that are related to the kidney bone disease, including calcitriol (active vitamin D) deficiency, 25(OH)-vitamin D deficiency, biochemical hyperparathyroidism, relatively low parathyroid hormone (PTH) level, increased serum alkaline phosphatase (hyperphosphatasemia), elevated fibroblast growth factor (FGF)-23, high turnover bone disease, adynamic bone disease, uremic osteoporosis, vascular calcification, hyper- and hypophosphatemia, and hyper- and hypocalcemia. We present a critical review of these 14 conditions with emphasis on patient survival and other pertinent clinical outcomes. We also review unresolved controversies surrounding the management of these conditions by administration of nutritional vitamin D (ergocalciferol and cholecalciferol), vitamin D receptor activators (calcitriol, alphacalcidiol, doxercalciferol), D-mimetics (paricalcitol, maxacalcitol), calcimimetics (cinacalcet), recombinant PTH (teriparatide), and receptor activator of nuclear factor-kappaB ligand modulators (denosumab); compare mortality predictability of PTH and alkaline phosphatase; and examine potential risks of bone disorders and mineral disarrays in CKD patients. PMID:20671739

  5. The neural receptor protein tyrosine phosphatase DPTP69D is required during periods of axon outgrowth in Drosophila.

    PubMed Central

    Desai, Chand; Purdy, Joy

    2003-01-01

    We have isolated and characterized a series of 18 chemically induced alleles of Ptp69D ranging in strength from viable to worse than null, which represent unique tools for probing the structure, function, and signaling pathway of DPTP69D. Three alleles are strongly temperature sensitive and were used to define the developmental periods requiring DPTP69D function; adult health requires DPTP69D during the mid- to late-pupal stage, eclosion requires DPTP69D during the early to mid-larval stage, and larval survival requires DPTP69D during embryogenesis. Mutations predicted to abolish the phosphatase activity of the membrane proximal D1 domain severely reduce but do not abolish DPTP69D function. Six alleles appear null; only 20% of null homozygotes pupate and <5% eclose, only to fall into the food and drown. One allele, Ptp69D(7), confers axon and viability defects more severe than those of the null phenotype. Sequence analysis predicts that Ptp69D(7) encodes a mutant protein that may bind but not release substrate. Like mutations in the protein tyrosine phosphatase gene Dlar, strong Ptp69D alleles cause the ISNb nerve to bypass its muscle targets. Genetic analysis reveals that the bypass defect in Dlar and Ptp69D mutants is dependent upon DPTP99A function, consistent with the hypothesis that DPTP69D and DLAR both counteract DPTP99A, allowing ISNb axons to enter their target muscle field. PMID:12807778

  6. Defining "Folklore" in the Classroom.

    ERIC Educational Resources Information Center

    Falke, Anne

    Folklore, a body of traditional beliefs of a people conveyed orally or by means of custom, is very much alive, involves all people, and is not the study of popular culture. In studying folklore, the principal tasks of the folklorist have been defined as determining definition, classification, source (the folk), origin (who composed folklore),…

  7. Defined by Word and Space

    ERIC Educational Resources Information Center

    Brisco, Nicole D.

    2010-01-01

    In the author's art class, she found that many of her students in an intro art class have some technical skill, but lack the ability to think conceptually. Her goal was to create an innovative project that combined design, painting, and sculpture into a compact unit that asked students how they define themselves. In the process of answering this…

  8. Phosphatase activity in the limb bones of monkeys (Lagothrix humboldti) with hyperparathyroidism

    PubMed Central

    Jeffree, Grace M.

    1962-01-01

    The paper reports a study of the distribution of phosphatases in the femora of three specimens of Humboldt's woolly monkey (Lagothrix humboldti) suffering from chronic hyperparathyroidism. Bone structure ranged from the apparently normal to extreme osteitis fibrosa. Most marked changes were found in the distribution of alkaline phosphatase, which reached at least 10 times the normal levels in the bone of the second monkey in the series, dropping to levels still well above normal in that of the most severely affected animal. Very high concentrations were found in the deeper layers of hypertrophied growth cartilage and in the osteoblasts lining poorly calcified trabeculae, and high concentrations in the fibre bone of the third animal. Lack of mineralization and the development of osteitis fibrosa are thus associated with a marked increase in alkaline phosphatase activity. Osteoclasts reacted strongly for acid phosphatase but were negative for alkaline phosphatase. Acid phosphatase levels were comparatively high in fibre bone, but overall levels ranged from 1/20 to less than 1/100 those of alkaline phosphatase. Some slow staining for acid phosphatase probably represents residual activity at acid pH of the markedly increased alkaline phosphatase. There may be some association between a failure of mineralization and the presence of acid phosphatase in osteoclasts and osteoid. The aetiology of the monkeys' condition is discussed. It seems likely that the parathyroid hypertrophy and rachitic changes were caused by low blood calcium dependent on a low calcium diet and lack of vitamin D, in which the requirements of New World monkeys are reputedly high. Images PMID:14451521

  9. The Nuclear Envelope Protein, LAP1B, Is a Novel Protein Phosphatase 1 Substrate

    PubMed Central

    Santos, Mariana; Rebelo, Sandra; Van Kleeff, Paula J. M.; Kim, Connie E.; Dauer, William T.; Fardilha, Margarida; da Cruz e Silva, Odete A.; da Cruz e Silva, Edgar F.

    2013-01-01

    Protein phosphatase 1 (PP1) binding proteins are quintessential regulators, determining substrate specificity and defining subcellular localization and activity of the latter. Here, we describe a novel PP1 binding protein, the nuclear membrane protein lamina associated polypeptide 1B (LAP1B), which interacts with the DYT1 dystonia protein torsinA. The PP1 binding domain in LAP1B was here identified as the REVRF motif at amino acids 55-59. The LAP1B:PP1 complex can be immunoprecipitated from cells in culture and rat cortex and the complex was further validated by yeast co-transformations and blot overlay assays. PP1, which is enriched in the nucleus, binds to the N-terminal nuclear domain of LAP1B, as shown by immunocolocalization and domain specific binding studies. PP1 dephosphorylates LAP1B, confirming the physiological relevance of this interaction. These findings place PP1 at a key position to participate in the pathogenesis of DYT1 dystonia and related nuclear envelope-based diseases. PMID:24116158

  10. Structural characterization of the reaction pathway in phosphoserine phosphatase: Crystallographic 'snapshots' of intermediate states.

    SciTech Connect

    Wang, Weiru; Cho, Ho S.; Kim, Rosalind; Jancarik, Jaru; Yokota, Hisao; Nguyen, Henry H.; Grigoriev, Igor V.; Wemmer, David E.; Kim, Sung-Hou

    2004-04-12

    Phosphoserine phosphatase (PSP) is a member of a large class of enzymes that catalyze phosphoester hydrolysis using a phosphoaspartate enzyme intermediate. PSP is a likely regulator of the steady-state-serine level in the brain, which is a critical co-agonist of the N-methyl--aspartate type of glutamate receptors. Here, we present high-resolution (1.5 1.9 Angstrom) structures of PSP from Methanococcus jannaschii, which define the open state prior to substrate binding, the complex with phosphoserine substrate bound (with a D to N mutation in the active site), and the complex with AlF3, a transition-state analog for the phospho-transfer steps in the reaction. These structures, together with those described for the BeF3- complex (mimicking the phospho-enzyme) and the enzyme with phosphate product in the active site, provide a detailed structural picture of the full reaction cycle. The structure of the apostate indicates partial unfolding of the enzyme to allow substrate binding, with refolding in the presence of substrate to provide specificity. Interdomain and active-site conformational changes are identified. The structure with the transition state analog bound indicates a ''tight'' intermediate. A striking structure homology, with significant sequence conservation, among PSP, P-type ATPases and response regulators suggests that the knowledge of the PSP reaction mechanism from the structures determined will provide insights into the reaction mechanisms of the other enzymes in this family.