Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the distribution of phosphorylation sites in murine lamins A and C (A-type lamins) in vitro and in vivo followed by reverse-phase high-performance liquid chromatography and microsequencing of peptides spanning the almost complete lamin sequence. We show that two distinct protein kinases, cell-division-cycle-2 kinase (cdc2 kinase) and protein kinase C (PKC), phosphorylate murine A-type lamins at the non-alpha-helical amino- and carboxy-terminal domains in vitro and in vivo. Cdc2 kinase, but not PKC, is capable of inducing depolymerization of the nuclear lamina in permeabilized cells. Accordingly, lamins were proposed to be direct in vivo substrates of cdc2 kinase and PKC with different effects on the lamina dynamics. Analysis of the original A-type lamins revealed phosphorylation of residues Ser5 and Ser392. Residue Ser392 was substoichiometrically phosphorylated in the substrate and by cdc2 kinase in vitro. PKC phosphorylated peptides with its kinase-specific motifs surrounding Ser5, Thr199, Thr416, Thr480 and Ser625. In vivo, a mitosis-specific phosphorylation at the cdc2-kinase-specific phosphoacceptor site Ser392 and of the N-terminal peptide was identified. An interphase-specific phosphorylation at Ser525 matching the PKC consensus sequence and of peptides phosphorylated by unknown kinases was determined. The results lead us to propose that different cyclin-dependent kinase activities act as lamin kinases in mitosis and in interphase. Other kinases may cooperate with cdc2 kinase during reversible disassembly in mitosis and may modulate the supramolecular assembly of lamin filaments.
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PMID:Identification of novel phosphorylation sites in murine A-type lamins. 847 40

The myristoylated aline-rich protein kinase C substrate (MARCKS) is a peripheral membrane protein that undergoes phosphorylation-dependent translocation between membrane and cytosol. MARCKS binds to acidic phospholipids with high affinity (Kd less than 0.5 microM) but binds poorly to neutral phospholipids. Although interaction of MARCKS with acidic phospholipids lacks specificity when determined by binding assay, these phospholipids exert distinctive effects on the phosphorylation of this protein by protein kinase C (PKC). Preincubation of MARCKS with phosphatidylserine (PS) or phosphatidylglycerol enhanced the phosphorylation; whereas with phosphatidic acid, phosphatidylinositol (PI), phosphatidylinositol-4-phosphate, or phosphatidylinositol-4,5-biphosphate inhibited the phosphorylation of this substrate by PKC. Phosphoinositide inhibition of MARCKS phosphorylation was apparently directed at the substrate rather than at the kinase as the phosphorylation of two other phospholipid-binding PKC substrates, neuromodulin and neurogranin, exhibited different responses from those of MARCKS. Furthermore, the inhibition of phosphoinositides on MARCKS phosphorylation was seen with PKC isozymes alpha, beta, gamma, and delta and with the catalytic fragment of PKC, protein kinase M. A 25-amino-acid synthetic peptide corresponding to the phosphorylation site domain (PSD) of MARCKS, but not to the myristoylated N-terminal peptide, competed equally effectively with MARCKS in binding to either PS- or PI-containing vesicles, suggesting that both phospholipids bind to the PSD of MARCKS. Binding of PI to MARCKS inhibited PKC phosphorylation of all three phosphorylation sites. These results suggest that phosphoinositides and PS bind at different residues within the MARCKS PSD, so that the resulting phospholipid/MARCKS complexes are differentially phosphorylated by PKC.
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PMID:Binding of myristoylated alanine-rich protein kinase C substrate to phosphoinositides attenuates the phosphorylation by protein kinase C. 861 Oct 23

Binding of the multimeric adhesive glycoprotein, von Willebrand Factor (vWF), to the platelet membrane glycoprotein (GP) Ib-IX-V complex mediates platelet adhesion and initiates signal transduction leading to platelet activation. Recently described viper venom proteins that bind to the GP Ib alpha-chain and inhibit vWF binding provide novel probes for studying receptor function. We have purified a 50-kDa form of alboaggregin from the white-lipped tree viper (Trimeresurus albolabris) and two 25-kDa proteins, CHH-A and CHH-B, from the timber rattlesnake (Crotalus horridus horridus) in addition to a previously described 25-kDa alboaggregin and echicetin. Complete or partial amino acid sequencing of CHH-A, CHH-B, and 50-kDa alboaggregin and cross-reactivity of these proteins with an anti-botrocetin antiserum confirmed that they were disulfide-linked heterodimers or higher multimers of the C-type lectin protein family. These proteins, together with 25-kDa alboaggregin and echicetin, specifically bound to GP Ib alpha within the N-terminal peptide domain, His-1-Glu-282, and inhibited vWF binding with comparable IC50 values (approximately 0.2 microgram/mL). However, cross-blocking studies between these structurally related proteins and anti-GP Ib alpha monoclonal antibodies demonstrated that the venom protein binding sites were not congruent. Further, the 50-kDa alboaggregin, but not the other venom proteins, potently induced platelet activation as assessed by dense granule serotonin release or elevation of cytosolic ionized calcium. Treatment of platelets with the 50-kDa alboaggregin was associated with activation of protein kinase C and tyrosine kinase(s), resulting in a platelet protein phosphorylation profile similar to that seen on shear-stress-induced vWF binding to platelets. These results suggest that the 50-kDa alboaggregin induces cytoplasmic signaling coincident with its binding to the GP Ib-IX-V complex and provides a potentially useful probe for studying the mechanism of vWF-dependent platelet activation.
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PMID:Binding of a novel 50-kilodalton alboaggregin from Trimeresurus albolabris and related viper venom proteins to the platelet membrane glycoprotein Ib-IX-V complex. Effect on platelet aggregation and glycoprotein Ib-mediated platelet activation. 882 1

In response to stimulation of B-cells through cell surface IgM, the activity of the serine/threonine protein phosphatase PP1, but not PP2A, was transiently decreased and reached a minimum 10-20 min after the stimulation. The decrease was more profound in the immature B-cell line WEHI-231, than in the mature B-cell line BAL-17. Under these conditions, PP1alpha, an isoform of PP1, showed unique alterations in the patterns of several spots with distinct isoelectic points in the Western blot after two-dimensional electrophoresis, whereas another isoform, PP1delta, did not show any alteration. PP1gamma1 and PP1gamma2 were not detected in B-cells. Similar alterations in these spots were observed in B-cells stimulated by PMA. When partially purified PP1 consisting of PP1alpha and PP1delta was incubated with [gamma-32P]ATP and PKC, radioactive spots of PP1alpha could be detected, but no spot of PP1delta was detected. Because differences in sequence among PP1 isoforms are mostly restricted to their C-terminals, phosphorylation rates of the C-terminal peptides containing the PKC-phosphorylation motif were compared. The C-terminal peptide of PP1alpha is a better substrate for PKC than those of PP1gamma1 and PP1gamma2, and is phosphorylated at the serine residue corresponding to Ser-325 of PP1alpha. The corresponding C-terminal region of PP1delta does not contain the phosphorylation site. On the other hand, there was a large difference in subcellular distribution of PP1delta, but not PP1alpha, between immature and mature B-cells. From these results, it was strongly suggested that PP1alpha is involved, via phosphorylation by PKC, in the regulation of signal transduction in response to the stimulation of B-cells through cell surface IgM.
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PMID:Alterations in type-1 serine/threonine protein phosphatase PP1alpha in response to B-cell receptor stimulation. 939 75

MARCKS, the major protein kinase C substrate in various cells and tissues, binds to calmodulin, acidic membrane phospholipids, and actin filaments, and these interactions are regulated by protein phosphorylation. We have previously shown that MARCKS purified from bovine brain is phosphorylated not only by protein kinase C but also by so-called proline-directed protein kinases in the well conserved N-terminal half of the molecule (Taniguchi, H., Manenti, S., Suzuki, M., and Titani, K. (1994) J. Biol. Chem. 269, 18299-18302). Although the presence of other phosphorylation sites in the C-terminal peptide was also noticed, the ambiguity in the C-terminal domain of the bovine protein hampered a more detailed analysis. In the present study, we analyzed MARCKS purified from rat brain by electrospray ionization/ion trap mass spectrometry. The results obtained revealed two additional novel phosphorylation sites in the C-terminal region. Both phosphorylation sites (Ser291 and Ser299) are immediately followed by proline, suggesting that these sites are also phosphorylated by the proline-directed protein kinase(s). Since Ser299 is within the C-terminal domain, which is well conserved among various species, the function of the domain, whatever it is, seems to be controlled by phosphorylation.
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PMID:The C-terminal conserved domain of MARCKS is phosphorylated in vivo by proline-directed protein kinase. Application of ion trap mass spectrometry to the determination of protein phosphorylation sites. 946 86

We have previously shown that protein kinase C-beta (PKC-beta) is required for activation of tyrosinase (Park, H. Y., Russakovsky, V., Ohno, S., and Gilchrest, B. A. (1993) J. Biol. Chem. 268, 11742-11749), the rate-limiting enzyme in melanogenesis. We now examine its mechanism of activation in human melanocytes. In vivo phosphorylation experiments revealed that tyrosinase is phosphorylated through the PKC-dependent pathway and that introduction of PKC-beta into nonpigmented human melanoma cells lacking PKC-beta lead to the phosphorylation and activation of tyrosinase. Preincubation of intact melanosomes with purified active PKC-beta in vitro increased tyrosinase activity 3-fold. By immunoelectron microscopy, PKC-beta but not PKC-alpha was closely associated with tyrosinase on the outer surface of melanosomes. Western blot analysis confirmed the association of PKC-beta with melanosomes. Only the cytoplasmic (extra-melanosomal) domain of tyrosinase, which contains two serines but no threonines, was phosphorylated by the serine/threonine kinase PKC-beta. These two serines at positions 505 and 509 both are present in the C-terminal peptide generated by trypsin digestion of tyrosinase. Co-migration experiments comparing synthetic peptide standards of all three possible phosphorylated tryptic peptides, a diphosphopeptide and two monophosphopeptides, to tyrosinase-phosphorylated in intact melanocytes by PKC-beta and then subjected to trypsin digestion revealed that both serine residues are phosphorylated by PKC-beta. We conclude that PKC-beta activates tyrosinase directly by phosphorylating serine residues at positions 505 and 509 in the cytoplasmic domain of this melanosome-associated protein.
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PMID:Protein kinase C-beta activates tyrosinase by phosphorylating serine residues in its cytoplasmic domain. 1034 9

Convertases are proteases responsible for the bioactivation of many proteins and peptides having a potential role in ontogenesis. As a model to study regulation of convertases in embryo, we use the P19 embryonal carcinoma cell line, which can differentiate into various cell types. The expression of convertase PC2 and its specific binding peptide 7B2 are co-induced during neuronal differentiation of P19 cells. We investigated the possibility that expression of both proteins may be coregulated by T3 and dexamethasone, activators of nuclear receptors, isobutylmethylxanthine, and dibutyryl cAMP, activators of protein kinase A, and phorbol 12-myristate 13-acetate, an activator of protein kinase C. Western blotting results show that expression of PC2 and 7B2 can be upregulated by modulators of the protein kinases, and upregulation needs not be strictly stoichiometric.
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PMID:Coordinate regulation of neuroendocrine convertase PC2 and peptide 7B2 in P19 neurons. 1079 18

GAP-43 protein of nerve terminals (B-50, F1, F57, pp46, neuromodulin) is thought to be one of key proteins involved in the control of outgrowth of neurites, release of neuromediators, synapse plasticity, etc. GAP-43 is usually considered as a whole protein. Along with the intact protein, nerve cells also contain two large native fragments of GAP-43 deprived of four or of about forty N-terminal amino acid residues (GAP-43-2 and GAP-43-3, respectively). The full-length GAP-43 is predominant in the mature brain. However, the ratio of the full-length protein and its fragments can vary under different physiological conditions. Changes in the GAP-43 proteins (the full-length protein and its fragments) were studied during embryonal and postnatal development of rat brain. The GAP-43 proteins were found to be expressed not later than on the 12-13th day of embryogenesis. Then their contents increased, and, until the 10th day after birth, GAP-43-3 dominated rather than the full-length protein. It is suggested that during this period the activity of a specific protease, which cleaves the N-terminal peptide of about 40 residues from the full-length GAP-43 molecule, is increased. The cleavage occurs in the region responsible for the interaction of GAP-43 with calmodulin. In the full-length molecule, this region is responsible also for the recognition of Ser41 residue by protein kinase C during phosphorylation. Another functionally important region that determines, in particular, the attachment of GAP-43 to the plasma membrane is cleaved from the main part of the molecule together with the N-terminal peptide. Thus, the specific fragmentation of GAP-43 that depends on developmental stage should be considered as a controlled structural rearrangement fundamentally affecting the functions of this protein.
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PMID:Enhanced level of site-specific proteolysis of GAP-43 protein during early stages of brain development. 1109 58

A physical and functional interaction between the Ca(2+)-binding protein Mts1 (S100A4) and the tumor suppressor p53 protein is shown here for the first time. We demonstrate that Mts1 binds to the extreme end of the C-terminal regulatory domain of p53 by several in vitro and in vivo approaches: co-immunoprecipitation, affinity chromatography, and far Western blot analysis. The Mts1 protein in vitro inhibits phosphorylation of the full-length p53 and its C-terminal peptide by protein kinase C but not by casein kinase II. The Mts1 binding to p53 interferes with the DNA binding activity of p53 in vitro and reporter gene transactivation in vivo, and this has a regulatory function. A differential modulation of the p53 target gene (p21/WAF, bax, thrombospondin-1, and mdm-2) transcription was observed upon Mts1 induction in tet-inducible cell lines expressing wild type p53. Mts1 cooperates with wild type p53 in apoptosis induction. Our data imply that the ability of Mts1 to enhance p53-dependent apoptosis might accelerate the loss of wild type p53 function in tumors. In this way, Mts1 can contribute to the development of a more aggressive phenotype during tumor progression.
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PMID:Tumor suppressor p53 protein is a new target for the metastasis-associated Mts1/S100A4 protein: functional consequences of their interaction. 1127 47

Plasma membrane-anchored proteases have key roles in cell signaling, migration and refashioning the cell surface and its surroundings. We report the first example of a plasma membrane-anchored protease on mature sperm, testase 1 (ADAM 24). Unlike other studied sperm ADAMs (fertilin alpha and beta, cyritestin) whose metalloprotease domains are removed during sperm development, we found testase 1 retains an active metalloprotease domain, suggesting it acts as a protease on mature sperm. Testase 1 is a glycoprotein (molecular mass 88 kDa), localized to the equatorial region of the plasma membrane of cauda epididymal sperm. Typically, proteolytic removal of the pro-domain is an initial activation step for ADAM proteases. The pro-domain of the testase 1 precursor (108 kDa) is proteolytically removed as sperm transit the caput epididymis to produce processed (mature) testase 1 (88 kDa). Testase 1 is unique among all studied ADAMs in that its proteolytic processing occurs on the sperm plasma membrane instead of at an intracellular site (the Golgi). Using GST-fusion proteins and a synthetic testase 1 C-terminal peptide, we found that the cytoplasmic tail of testase 1 could be phosphorylated in vitro by protein kinase C (PKC). Thus testase 1 apparently has a cytoplasmic PKC phosphorylation site(s). Protein kinase C is known to stimulate other ADAMs' protease activity. Because events of the acrosome reaction include PKC activation, we speculate that testase 1 protease function could be important in sperm penetration of the zona pellucida after sperm PKC is activated during the acrosome reaction.
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PMID:Testase 1 (ADAM 24) a plasma membrane-anchored sperm protease implicated in sperm function during epididymal maturation or fertilization. 1130 8


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