Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Both E. coli and calf thymus DNA polymerase can be phosphorylated by cAMP-dependent protein kinase and phosphorylation appears to stimulate the DNA polymerase reaction. Conversely, dephosphorylation of the polymerase molecule, by a protein phosphatase, inhibits the polymerase reaction.
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PMID:Phosphorylation of DNA polymerase. 17 41

We have shown that an acidic phosphoprotein phosphatase (APP-ase) has a different pattern of postnatal maturation in the spleen, thymus and liver of rats and mice. The APP-ase activity increases during the first eight months of postnatal life in the spleen of rats (when it attains an 8--10 times higher value than at birth) and up to the sixth month of life in the spleen of mice. It increases considerably during the first two weeks of postnatal life in the thymus of rats and mice; in the liver of rats it reaches maximum activity before birth, but continues to increase up to the sixth month of postnatal life in the liver of mice. The results show also that the APP-ase from the spleen, thymus and liver of rats is equally active in dephosphorylating ATP and phenyl phosphate during the whole life span of rats, but not in relation to beta-glycerol phosphate. After analyzing its substrate specificity, its pH dependence in relation to different substrates, its kinetic properties, as well as its behaviour towards ascorbic acid and different inhibitors (sodium tungstate and sodium molybdate, L-tartrate, L-phenylalanine and L-cysteine) we have come to the conclusion that the rat spleen APP-ase is different from "nonspecific" acid and alkaline phosphatases and very similar to the EC 3.1.3.16 acid phosphoprotein phosphatase.
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PMID:The ontogenetic evolution of acidic phosphoprotein phosphatase activity in the lymphatic tissue and the liver of the rat. 21 22

The differential assay conditions for protein phosphatases PP1, PP2A, and PP2C were extensively studied by using crude extracts from mouse lymphoid tissues as enzyme sources. Under these conditions, the protein phosphatase activities were measured in MRL/MpJ-lpr/lpr mice (MRL/lpr mice), autoimmune-prone mice, and MRL/MpJ(-)+/+ mice (MRL/+/+ mice) and C3H/HeJ mice as the controls. In MRL/lpr mice, significant alterations in protein phosphatase activities from those in the control mice were demonstrated. In spleen and liver from MRL/lpr mice, potential activities of PP1 and PP2A were distinctly elevated over those of the control mice. These elevations appeared to be due to accumulation of the abnormal lymphocytes that emerged in MRL/lpr mice. Although the PP1 activity in MRL/lpr lymph nodes was lower than those of normal spleen and thymus, it was greatly increased by Co(2+)-trypsin treatment so that the PP1 activity of MRL/lpr lymph nodes was the highest among those of all the tissues examined. In contrast, PP2C activity showed no remarkable alteration in the autoimmune disease model mice as compared with that in the control mice. These results demonstrated a specific elevation in potency of protein dephosphorylation in the tissues of MRL/lpr mice, suggesting a new explanation for the defect in signal transduction in this disease.
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PMID:Increase in potential activities of protein phosphatases PP1 and PP2A in lymphoid tissues of autoimmune MRL/MpJ-lpr/lpr mice. 131 90

Nuclei from bovine thymus contain a high level of partially latent protein phosphatase 1 (PP-1). More than 90% of this PP-1 is associated with the insoluble chromatin/matrix fraction and can be extracted with 0.3 M NaCl. The salt extract also contains three heat- and acid-stable inhibitory proteins of PP-1 that can be resolved on Mono Q. We have purified two of these nuclear inhibitors of PP-1 (NIPP-1a and NIPP-1b) until homogeneity. They are acidic proteins (pI = 4.4) with a molecular mass of 18 kDa (NIPP-1a) and 16 kDa (NIPP-1b) on SDS-PAGE. Judged from the larger molecular mass that was deduced from gel filtration (35 kDa), NIPP-1a and NIPP-1b appear to be asymmetric or dimeric proteins. The nuclear inhibitors totally inhibited the phosphorylase phosphatase activity of PP-1, but even at a 250-fold higher concentration they did not affect the activities of the other major serine/threonine protein phosphatases (PP-2A, PP-2B, and PP-2C). NIPP-1a and NIPP-1b inhibited the catalytic subunit of PP-1 with an extrapolated Ki of about 1 pM, which is some three orders of magnitude better than the cytoplasmic proteins inhibitor 1/DARPP-32 and modulator. The nuclear inhibitors were not inactivated by incubation with protein phosphatases that inactivate inhibitor 1 and DARPP-32. Unlike modulator, they were not able to convert the catalytic subunit of PP-1 into a MgATP-dependent form. Remarkably, the extent of inhibition of PP-1 by NIPP-1b depended on the nature of the substrate. The phosphorylase phosphatase and casein phosphatase activities of PP-1 were completely blocked by NIPP-1b, whereas the dephosphorylation of basic proteins was either not at all inhibited (histone IIA) or only partially (myelin basic protein). These data may indicate that the acidic NIPP-1b is inactivated through complexation by basic proteins. Indeed, nonphosphorylated histone IIA antagonized the inhibitory effect of NIPP-1b on the casein phosphatase activity of PP-1. Our data show that the nucleus contains specific and potent inhibitory proteins of PP-1 that differ from earlier described cytoplasmic inhibitors. We suggest that these novel proteins may control the activity of nuclear PP-1 on its natural substrate(s).
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PMID:The isolation of novel inhibitory polypeptides of protein phosphatase 1 from bovine thymus nuclei. 132 7

Changes in intracellular free Ca2+ are involved in the transmembrane signalling of different cells, including lymphocytes. Since calmodulin (CaM) is a primary receptor for Ca2+ (ref. 4), it may mediate the activation of crucial enzymes after antigen-induced increases in cytosolic Ca2+. Using a biotinylated-CaM (Bio-CaM) detection procedure to identify such proteins, we found that a peptide of relative molecular mass 59,000 (59K) was the predominant soluble CaM-binding protein (CaM-BP) in T cells and B lymphocytes from murine spleen; immunoblotting experiments identified it as a subunit of the CaM-dependent phosphatase, 'calcineurin' (CN). Smaller amounts of larger CaM-BPs, thought to be cytoskeletal-binding proteins, were also detected. CaM-BPs were expressed differentially, with B lymphocytes having four times more of the CN-like protein than T lymphocytes, while in thymocytes, a 65K polypeptide was the major CaM-BP. However, limited proteolysis analysis suggested that this thymus-specific peptide may be a precursor of CN. These data suggest that Ca2+-stimulated protein dephosphorylation may be an important and highly regulated function in lymphoid cells.
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PMID:Differential expression of calmodulin-binding proteins in B, T lymphocytes and thymocytes. 349 72

The Ca2+-dependent regulator protein (CDR), also frequently termed "calmodulin" was determined to influence the dephosphorylation of mixed calf thymus histones or purified histones 1, 2A, or 2B by a partially purified bovine brain phosphoprotein phosphatase. CDR increase the rate of dephosphorylation of mixed histones more than 20-fold. With increasing concentrations of mixed histones as substrate, a proportionate increase of CDR concentration was required to maintain maximal expression of histone phosphatase activity. Mixed histones suppressed the activation by CDR of a bovine brain cyclic nucleotide phosphodiesterase activity, with activation being restored by increased quantities of CDR. Dephosphorylation of casein and phosphorylase alpha by the phosphatase preparation was not affected by CDR. These observations support the interpretation that the effects of CDR on histone dephosphorylation are substrate-directed. The rates of dephosphorylation of histones 1, 2A, and 2B by the phosphatase were 4- to 12-fold more rapid at low (sub-micromolar) concentrations of free Ca2+ than at high (200 microM) Ca2+ in incubations containing CDR, but they were unaffected by Ca2+ in incubations without CDR. The addition of stoichiometric quantities of calmodulin increased the apparent Km of the phosphatase for the various histones 2- to 6-fold, while maximal velocities were 4- to 12-fold higher at low than at high added Ca2+. The inhibitory effect of Ca2+ on histone dephosphorylation was immediately reversible by chelation of Ca2+ with EDTA. Ca2+-dependent inhibition of histone 1 or 2B phosphatase activities was also produced by rabbit skeletal muscle troponin C, but not by rabbit skeletal muscle parvalbumin, by poly(L-aspartate) or poly(L-glutamate). The phosphorylated fragment from the NH2-terminal region of either H2A (generated by treatment with N-bromosuccinimide) or H2B (generated by treatment with cyanogen bromide) was dephosphorylated by the phosphatase, with the rates of dephosphorylation being reduced 3- to 6-fold by Ca2+ in incubations containing CDR.
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PMID:Interaction of calmodulin with histones. Alteration of histone dephosphorylation. 625 89

NIPP-1 was originally isolated as a potent and specific nuclear inhibitory polypeptide (16-18 kDa) of protein phosphatase-1. We report here the cDNA cloning of NIPP-1 from bovine thymus and show that the native polypeptide consists of 351 residues and has a calculated mass of 38.5 kDa. The bacterially expressed central third of NIPP-1 completely inhibited the type-1 catalytic subunit, but displayed a reduced inhibitory potency after phosphorylation by protein kinase A and casein kinase 2. Translation of NIPP-1 mRNA in reticulocyte lysates resulted in the accumulation of both intact NIPP-1 and a smaller polypeptide generated by alternative initiation at the codon corresponding to Met143. A data base search showed that the COOH terminus of NIPP-1 is nearly identical to the human ard-1 protein (13 kDa), which has been implicated in RNA processing (Wang, M., and Cohen, S. N. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 10591-10595). Comparison of the cDNAs encoding ard-1 and NIPP-1 suggests that their mRNAs are generated by alternative splicing of the same pre-mRNA. Western blotting with antibodies against the COOH terminus of NIPP-1, however, showed a single polypeptide of 47 kDa, which was enriched in the nucleus. Northern analysis revealed a single transcript of 2.2 kilobases in bovine thymus and of 2.4 kilobases in various human tissues.
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PMID:Molecular cloning of NIPP-1, a nuclear inhibitor of protein phosphatase-1, reveals homology with polypeptides involved in RNA processing. 749 93

We have previously identified hsp56, a protein component of steroid receptor complexes, as an FK506 binding protein [Yem et al. (1992) J. Biol. Chem. 267, 2868-2871]. We now report that hsp56 is also found to be a major immunophilin in chicken thymus, by virtue of binding to FK506-Affi-Gel-10 as well as positive cross-reactivity with a polyclonal antiserum directed against human hsp56. Limited digests of purified chicken hsp56 with endoproteinase Lys C result in the production of a unique polypeptide having a mass of about 17 kDa (p17), as judged by Western blotting. Peptide mapping provided additional proof that p17 is a fragment which comprises the entire FK506 binding domain I of chicken hsp56, terminating with an Arg-Lys which might represent a processing site. Binding of radiolabeled dihydro FK506 to p17 is saturable with a calculated KD of 42 nM. Since size exclusion chromatography of drug-p17 complexes indicates that the active species is a homodimer with a mass of 30-40 kDa, the stoichiometry calculated for the drug-protein complex is approximately 1:1. Furthermore, unlike FKBP-12, chicken p17 bound to FK506 does not bind to calcineurin-calmodulin complexes. This work demonstrates the excision of a domain from an hsp56 protein that is active in binding FK506 and functionally distinct from FKBP-12, a protein of similar size and structure.
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PMID:An active FK506-binding domain of 17,000 daltons is isolated following limited proteolysis of chicken thymus hsp56. 750 25

Milk protein gene expression in mammary epithelial cells is regulated by the action of the lactogenic hormones insulin, glucocorticoids and prolactin. The mammary gland factor, MGF, has been shown to be a central mediator in the lactogenic hormone response. The DNA binding activity of MGF is hormonally regulated and essential for beta-casein promoter activity. We have used Red A Sepharose- and sequence-specific DNA affinity chromatography to purify MGF from mammary gland tissue of lactating sheep. Proteins of 84 and 92 kDa were obtained, proteolytically digested and the resulting peptides separated by reverse phase high pressure liquid chromatography. The 84 and 92 kDa proteins yielded very similar peptide patterns. The amino acid sequence of two peptides was determined. The sequence information was used to derive oligonucleotide probes. A cDNA library from the mRNA of mammary gland tissue of lactating sheep was screened and a molecular clone encoding MGF was isolated. MGF consists of 734 amino acids and has sequence homology with the 113 (Stat113) and 91 kDa (Stat91) components of ISGF3, transcription factors which are signal transducers of IFN-alpha/beta and IFN-gamma. Two species of MGF mRNA of 6.5 and 4.5 kb were detected in mammary gland tissue of lactating sheep. Lower mRNA expression was found in ovary, thymus, spleen, kidney, lung, muscle and the adrenal gland. MGF cDNA was incorporated into a eukaryotic expression vector and cotransfected with a vector encoding the long form of the prolactin receptor into COS cells. A strong MGF-specific bandshift was obtained with nuclear extracts of COS cells induced with prolactin. Treatment of activated MGF with a tyrosine-specific protein phosphatase resulted in the loss of DNA binding activity. Prolactin-dependent transactivation of a beta-casein promoter-luciferase reporter gene construct was observed in transfected cells.
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PMID:Mammary gland factor (MGF) is a novel member of the cytokine regulated transcription factor gene family and confers the prolactin response. 788 87

The goal of this study was to identify the differences of intracellular signals between the processes of thymic positive and negative selection. The activation of calcineurin, a calcium- and calmodulin-dependent phosphatase, is known to be an essential event in T cell activation via the T cell receptor (TCR). The effect of FK506, an inhibitor of calcineurin activation, on positive and negative selection in CD4+CD8+ double positive (DP) thymocytes was examined in normal mice and in a TCR transgenic mouse model. In vivo FK506 treatment blocked the generation of mature TCRhighCD4+CD8- and TCRhighCD4-CD8+ thymocytes, and the induction of CD69 expression on DP thymocytes. In addition, the shutdown of recombination activating gene 1 (RAG-1) transcription and the downregulation of CD4 and CD8 expression were inhibited by FK506 treatment suggesting that the activation of calcineurin is required for the first step (or the very early intracellular signaling events) of TCR-mediated positive selection of DP thymocytes. In contrast, FK506-sensitive calcineurin activation did not appear to be required for negative selection based on the observations that negative selection of TCR alpha beta T cells in the H-2b male thymus (a negative selecting environment) was not inhibited by in vivo treatment with FK506 and that there was no rescue of the endogenous superantigen-mediated clonal deletion of V beta 6 and V beta 11 thymocytes in FK506-treated CBA/J mice. DNA fragmentation induced by TCR activation of DP thymocytes in vitro was not affected by FK506. In addition, different effects of FK506 from Cyclosporin A on the T cell development in the thymus were demonstrated. The results of this study suggest that different signaling pathways work in positive and negative selection and that there is a differential dependence on calcineurin activation in the selection processes.
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PMID:T cell receptor-mediated signaling events in CD4+CD8+ thymocytes undergoing thymic selection: requirement of calcineurin activation for thymic positive selection but not negative selection. 753 85


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