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

The delta-subspecies of protein kinase C (PKC) was purified to near homogeneity from the Triton X-100 extract of the rat brain particulate fraction by successive chromatographies on S-Sepharose Fast Flow, Phenyl 5PW, Heparin 5PW, hydroxyapatite, and Mono Q columns. The purified enzyme was doublet with molecular weight of 78 kDa and 76 kDa on SDS-PAGE. This doublet proteins were separated partially by Mono Q column chromatography, both of which were recognized by the antibodies raised against synthetic oligopeptides, parts of the deduced amino acid sequence of the rat delta PKC. Protein phosphatase 2A treatment suggested that the 78 kDa protein was a phosphorylated form of the 76 kDa protein. To confirm the structural and genetic identity of the doublet proteins, delta PKC was expressed in COS 7 cells by transfecting its cDNA-constructed plasmid, and was purified for comparison. This recombinant enzyme was also doublet. The enzymes isolated from the brain and COS 7 cells showed identical reactivities with delta PKC-specific antibodies, chromatographic behaviors, and V8 protease peptide mapping. In addition, these the enzyme preparations were indistinguishable from each other in their responses to phosphatidylserine, diacylglycerol, phorbol esters, free fatty acids, and Ca2+. Comparison was also made between the enzymological properties of delta PKC and alpha PKC, such as activation kinetics, sensitivity to protein kinase inhibitors and substrate specificity which were distinctly different from each other.
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PMID:Enzymatic properties of ubiquitously expressed delta-subspecies of protein kinase C differing from other members of protein kinase C family. 129 10

The zeta isoform of protein kinase C (PKC zeta) was purified to near homogeneity from the cytosolic fraction of bovine kidney by successive chromatography on DEAE-Sephacel, heparin-Sepharose, phenyl-5PW, hydroxyapatite, and Mono Q. The purified enzyme had a molecular mass of 78 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The protein was recognized by an antibody raised against a synthetic oligopeptide corresponding to the deduced amino acid sequence of rat PKC zeta. The enzymatic properties of PKC zeta were examined and compared with conventional protein kinase C purified from rat brain. The activity of PKC zeta was stimulated by phospholipid but was unaffected by phorbol ester, diacylglycerol, or Ca2+. PKC zeta did not bind phorbol ester, and autophosphorylation was not affected by phorbol ester. Unsaturated fatty acid activated PKC zeta, but this activation was neither additive nor synergistic with phospholipid. These results indicate that regulation of PKC zeta is distinct from that of other isoforms and suggest that hormone-stimulated increases in diacylglycerol and Ca2+ do not activate this isoform in cells. It is possible that PKC zeta belongs to another enzyme family, in which regulation is by a different mechanism from that for other isoforms of protein kinase C.
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PMID:Purification and characterization of the zeta isoform of protein kinase C from bovine kidney. 132 99

Noninsulin-dependent diabetes is associated with a decrease in the activity of sarcolemmal phosphatase 1, but no change in the activities of phosphatase 2A, 2B, or 2C. Also unaffected by diabetes were the activities of protein kinase C, cAMP-dependent protein kinase and calcium-calmodulin protein kinase. Because of the decrease in phosphatase 1 activity, 32P incorporation into sarcolemmal phosphoproteins catalyzed by either intrinsic protein kinases or extrinsic cAMP-dependent protein kinase was elevated in the diabetic. Among the proteins whose phosphorylation was elevated in diabetes was the phospholamban-like protein, which has been implicated in the regulation of ATP-dependent calcium transport. The phosphate-linked increase could be prevented by exposing the membranes to a phosphatase inhibitor and either extrinsic cAMP-dependent protein kinase or alamethicin. In addition to the phosphatase-linked effects, analysis of individual sarcolemmal phosphoproteins by SDS-polyacrylamide gel electrophoresis indicated that diabetes caused a specific elevation in membrane phosphorylation of some proteins (43 kDa and 78 kDa), but a decrease in the phosphorylation state of other phosphoproteins (31 kDa and 49 kDa). The data indicate that membrane phosphorylation is dramatically altered by diabetes. The possibility that this contributes to altered myocardial function is discussed.
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PMID:Defective sarcolemmal phosphorylation associated with noninsulin-dependent diabetes. 215 49

The effects of synthetic atrial natriuretic factor (ANF) on the state of protein phosphorylation in plasma membranes of bovine adrenal cortex have been studied in vitro. ANF (1x10(-8)M - 1x10(-7)M) specifically inhibited the phosphorylation of two distinct proteins of 78 kDa and 240 kDa. Immunoblotting with specific antiserum to protein kinase C produced evidence that 78 kDa protein is most likely the protein kinase C whose phosphorylation is inhibited by both ANF and cGMP. However, cGMP did not affect the phosphorylation of 240 kDa protein, indicating a new cGMP-independent mechanism of ANF action in the adrenal, which is compatible with the lack of action of cGMP and its analogs in ANF-induced inhibition of aldosterone secretion from adrenal cortex. The inhibition of phosphorylation of putative protein kinase C by ANF or cGMP indicates a hitherto unknown signal transduction mechanism of ANF.
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PMID:New signal transduction mechanisms of atrial natriuretic factor: inhibition of phosphorylation of protein kinase C and A 240 kDa protein in adrenal cortical plasma membrane by cGMP dependent and independent mechanisms. 282 65

In this study, we have shown that steady-state levels of glucose-regulated 78 kDa (GRP78) protein and messenger RNA increase during a 5-h exposure to 0.02% oxygen. This increase in GRP78 protein and mRNA induced by hypoxia can be abolished by a 1-h pretreatment of cells before hypoxia with the protein kinase C (PKC) inhibitors staurosporine and H7 at concentrations at which the drugs themselves do not cause cytotoxicity. Although all studies using protein kinase inhibitors must be interpreted with caution, staurosporine and H7 have been shown to be potent inhibitors of PKC activity, suggesting a role for PKC in mediating the transcriptional regulation of GRP78 by hypoxia. Further support for PKC in regulating GRP78 gene expression by hypoxia stems from gel-mobility shift studies in mixtures of nuclear extracts from aerobic or hypoxic cells with a 36 bp region of the GRP78 promoter (-170 to -135). Binding of this factor could be inhibited by pretreating cells with the PKC inhibitor staurosporine before hypoxia or activated by treating cells with the PKC-activating phorbol ester TPA. These data suggest that activation of this hypoxia-responsive factor is sensitive to oxygen levels and seems to be mediated through a PKC signal transduction pathway.
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PMID:The regulation of GRP78 and messenger RNA levels by hypoxia is modulated by protein kinase C activators and inhibitors. 814 29

Cellular motility, a prerequisite for metastasis of tumor cells, is affected by a 55-kDa tumor-cell-secreted cytokine which influences the migration of the producing cells and is called autocrine motility factor (AMF). Previous studies indicated that AMF stimulates motility by binding to its receptor, a cell-surface glycoprotein of 78 kDa (gp78), inducing its phosphorylation, activating a pertussis toxin (PT)-sensitive G-protein, and stimulating inositol metabolism. However, the intracellular signaling mechanisms which transduce and regulate the AMF motility response remain largely unknown. 12-(S)-HETE, a lipoxygenase metabolite of arachidonic acid which affects the cytoskeletal architecture of murine melanoma cells, also stimulates cell motility independently of PT-sensitive G-proteins and up-regulates gp78 surface expression. 12-(S)-HETE induces the phosphorylation of gp78 in a manner analogous to AMF and the motility response of these murine melanoma cells to both AMF and 12-(S)-HETE is inhibited by protein kinase C inhibitors. Furthermore, perturbation of the AMF receptor stimulated endogenous biosynthesis of 12(S)HETE. These results suggest the existence of an "autocrine motility cycle" which influences melanoma cell motility by gp78 activation, and production of second messengers which affect the cytoskeletal architecture and expression of the AMF receptor itself.
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PMID:Regulation of melanoma-cell motility by the lipoxygenase metabolite 12-(S)-HETE. 825 18

We have previously found that intra-hippocampal injection of H7, a protein kinase inhibitor, impairs memory retention in rats in a one-way passive avoidance learning task. It also decreases the optical density of several hippocampal protein bands on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The present study examined whether protein kinase C (PKC) and phosphorylation of its substrate protein are involved in the memory process. The same behavioral paradigm was used. The infusion volume was 0.8 microliter each side throughout all experiments. We have microinjected phorbol ester (TPA), a specific PKC activator, into the dentate gyrus (DG) of hippocampus immediately after training. Animals were subject to the retention test 24 hr after training. Results revealed that TPA enhanced retention performance and protein phosphorylation in rats in a dose-response fashion with doses at 0.8 and 2.0 ng reaching a significant behavioral effect. The high dose of TPA also increased phosphorylation of four protein bands in the cytoplasma with molecular weight (MW) around 48 kDa, 60 kDa, 78 kDa and 116 kDa, respectively; and seven protein bands in the membrane with MW around 38 kDa, 43 kDa, 48 kDa, 80 kDa, 88 kDa, 130 kDa and 210 kDa, respectively. In different animals, we have microinjected staurosporine, a specific PKC inhibitor, into the DG of hippocampus. Results indicated that at the low dose (0.5 ng), staurosporine was without a significant effect. At the middle and high doses (2.0 and 8.0 ng), it markedly impaired retention performance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protein kinase C activation facilitates memory retention in rats. 828 15

These studies demonstrate that treatment of human U-937 cells with ionizing radiation (IR) is associated with activation of a cytoplasmic myelin basic protein (MBP) kinase. Characterization of the kinase by gel filtration and in-gel kinase assays support activation of a 40 kDa protein. Substrate and inhibitor studies further support the induction of protein kinase C (PKC)-like activity. The results of N-terminal amino acid sequencing of the purified protein demonstrate identity of the kinase with an internal region of PKC delta. Immunoblot analysis was used to confirm proteolytic cleavage of intact 78 kDa PKC delta in control cells to the 40 kDa C-terminal fragment after IR exposure. The finding that both IR-induced proteolytic activation of PKC delta and endonucleolytic DNA fragmentation are blocked by Bcl-2 and Bcl-xL supports an association with physiological cell death (PCD). Moreover, cleavage of PKC delta occurs adjacent to aspartic acid at a site (QDN) similar to that involved in proteolytic activation of interleukin-1 beta converting enzyme (ICE). The specific tetrapeptide ICE inhibitor (YVAD) blocked both proteolytic activation of PKC delta and internucleosomal DNA fragmentation in IR-treated cells. These findings demonstrate that PCD is associated with proteolytic activation of PKC delta by an ICE-like protease.
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PMID:Proteolytic activation of protein kinase C delta by an ICE-like protease in apoptotic cells. 855 34

Mast cells (MC) can be stimulated to secrete by cross-linking immunoglobulin E bound to specific surface receptors, as well as in response to polycationic molecules such as substance P and compound 48/80. The antiallergic drug disodium cromoglycate (cromolyn) inhibited MC secretion and rapidly incorporated phosphate into a 78 kDa protein, speculated to be its mode of action. This protein was purified by single and two-dimensional gel electrophoresis, and was shown to be phosphorylated primarily on serine residues by protein kinase C. Partial amino acid sequencing of two generated fragments was identical to that of portions of mouse moesin, a member of the band 4.1 superfamily of proteins, with no definitive function known to date. Polyclonal antibodies raised against the rat basophil leukemia cell moesin cDNA expressed in Escherichia coli immunoprecipitated the 78 kDa phosphoprotein quantitatively, and immunocytochemistry localized it to the plasma membrane. Reversible phosphorylation of this 78 kDa phosphoprotein could affect its possible cytoskeletal binding through which it may regulate stimulus-secretion coupling in MC.
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PMID:Characterization of the 78 kDa mast cell protein phosphorylated by the antiallergic drug cromolyn and homology to moesin. 868 95

Mammary epithelial cells isolated from midpregnant BALB/c mice were grown within collagen gels and maintained in serum-free media containing 10 ng/ml epidermal growth factor (EGF) for an 8-day culture period. Western blot and scanning densitometric image analysis showed the presence of protein kinase C(PKC)alpha (82 kDa), delta(75 kDa), eta(90 and 78 kDa), and zeta(82, 74, and 65 kDa), whereas PKCbeta, gamma, and theta were not detected in either the cytosolic or membrane fractions in these cells. Cytosolic and membrane levels of PKCalpha and 82 kDa PKCzeta band progressively increased throughout the 8-day culture period. During this same time, cytosolic PKCdelta levels decreased, while membrane levels of PKCdelta showed no change. Cytosolic and membrane levels of PKCeta and the 74- and 65-kDa PKCzeta bands displayed some fluctuations but remained relatively constant during the 8-day culture period. Other studies showed that 24-hr treatment with 100 nM of phorbol 12-myristate 13-acetate (PMA), resulted in the downregulation of PKCalpha, delta, and eta, and the 82-kDa PKCzeta band. However, PMA treatment had no effect on cytosolic and membrane levels of the 74- and 65-kDa PKCzeta bands. Since PKC activation is associated with hormone- and growth factor-dependent mammary epithelial cell proliferation, these findings suggest that increases and/or decreases in the relative levels of the different PKC isoenzymes in proliferating cells may indicate their possible role in mediating or regulating EGF-dependent mitogenesis.
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PMID:Protein kinase C isoenzyme expression in normal mouse mammary epithelial cells grown in primary culture. 882 Aug 25


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