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)

Bovine heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) was phosphorylated by incubation with [gamma-32P]MgATP and cyclic AMP-dependent protein kinase (PKA) or protein kinase C (PKC). After digestion with chymotrypsin, the phosphorylation sites for the two protein kinases were identified by peptide mapping, and microsequencing. Evidence for new phosphorylation sites for PKA (Ser-483) and PKC (Ser-84 and Ser-466) was obtained.
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PMID:Evidence for new phosphorylation sites for protein kinase C and cyclic AMP-dependent protein kinase in bovine heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase. 132 69

The effects of carbobenzyloxy-leucine-tyrosine-chloromethylketone (zLYCK), an inhibitor of chymotrypsin, were investigated on the activation pathways of the human neutrophil respiratory burst. At 10 microM zLYCK, a parallel inhibition was observed of superoxide production stimulated with the chemo-attractant FMLP and of chymotrypsin-like activity of human neutrophils. By contrast, superoxide production induced by PMA was minimally affected by zLYCK. The known transduction pathways triggered by FMLP were analyzed. zLYCK did not affect either the FMLP-induced cytosolic free calcium transient, inositol 1,4,5 trisphosphate formation, nor the PMA-induced phosphorylation of the 47-kDa substrate of protein kinase C. zLYCK did not affect the activity of protein kinase C extracted from neutrophils. In Ca(2+)-depleted cells, in which phosphatidylinositol 4,5-biphosphate breakdown does not occur, zLYCK inhibited the FMLP-induced respiratory burst in cells primed by low doses of PMA. The activity of the NADPH oxidase tested with active membranes from stimulated neutrophils or in a cell-free system was not inhibited by zLYCK. We conclude that: 1) zLYCK inhibits superoxide production through the inhibition of a chymotrypsin-like protease of the neutrophil, 2) zLYCK inhibits FMLP-induced activation of NADPH oxidase through a pathway independent of PtdInsP2 breakdown and cytosolic free calcium, and 3) zLYCK may prove a useful probe for the characterization of its target protease in neutrophil activation.
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PMID:The chymotrypsin inhibitor carbobenzyloxy-leucine-tyrosine-chloromethylketone interferes with the neutrophil respiratory burst mediated by a signaling pathway independent of PtdInsP2 breakdown and cytosolic free calcium. 165 5

The ether lipid AMG (1-O-hexadecyl-2-O-methylglycerol) has previously been shown to have both enhancing and inhibitory effects on histamine release from isolated rat mast cells. In addition, a synergistic interaction with the phorbol ester TPA indicated protein kinase C activation. In the present investigation the effects of the related ether phospholipid AMG-PC (1-O-hexadecyl-2-O-methylglycero-3-phosphocholine) and the analogue hexadecylphosphocholine (miltefosine (HPC) are compared with those of AMG. HPC had only inhibitory effects, in contrast to AMG-PC which acted similarly on histamine release induced by compound 48/80, but had dual influence on responses to antigen and the ionophore A23187 and mainly exhibited a synergistic interaction with combinations of the ionophore and TPA. The influence of AMG-PC differed from that of AMG in some aspects whereas the character of its synergistic interaction with A23187 resembled that of AMG, in particular after pre-incubation with TPA. The results show that HPC does not share all biological activities of the antineoplastic ether lipids. They indicate that the effects of AMG-PC under appropriate conditions may be due to activation of protein kinase C but do not permit a distinction between direct effects and indirect through metabolic conversion to AMG.
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PMID:Effects of the ether phospholipid AMG-PC on mast cells are similar to that of the ether lipid AMG but different from that of the analogue hexadecylphosphocholine. 179 Nov 41

Ajoene, (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide, is a potent antiplatelet compound isolated from alcoholic extracts of garlic. In vitro, ajoene reversibly inhibits platelet aggregation as well as the release reaction induced by all known agonists. In this paper we show that ajoene has a unique locus of action, that is not shared by any other known antiplatelet compound. For example, ajoene inhibits agonist-induced exposure of fibrinogen receptors, as well as intracellular responses such as activation of protein kinase C and the increase in cytoplasmic free calcium induced by receptor-dependent agonists (collagen, ADP, PAF, low-dose thrombin). On the other hand, with agonists that can by-pass (at least partially) the receptor-transductor-effector sequence, such as high-dose thrombin, PMA, NaF, only the exposure of fibrinogen receptors is blocked by ajoene. Binding of fibrinogen to chymotrypsin-treated platelets is only slightly inhibited by ajoene. The results reported here also show that: (a) ajoene does not act as a calcium chelator, does not impair the initial agonist-receptor interaction and does not influence the basal levels of intracellular inhibitors of platelet activation such as cyclic GMP; (b) the locus of action of ajoene is a yet unknown molecular step that links, in the case of physiological agonists, specific agonist-receptor complexes to the sequence of the signal transduction system on the plasma membrane of platelets. In the case of non-physiological, receptor-independent agonists (PMA, NaF), we can only speculate on the hypothesis that they somehow mimic the effect of the agonist-receptor complexes on the signal transduction system; and (c) the exposure of fibrinogen receptors is not a direct consequence of other intracellular processes. These observations clearly show, for the first time, that the exposure of fibrinogen receptors is a membrane event proximally and obligatorily coupled to the occupancy of other membrane receptors by their agonists without any intervention by the cytoplasmic biochemical processes. Additional results support the involvement of G-proteins in these early events of platelet activation. Furthermore, a role of the beta tau subunits of G-proteins in the exposure of fibrinogen receptors is proposed.
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PMID:Evidence for direct coupling of primary agonist-receptor interaction to the exposure of functional IIb-IIIa complexes in human blood platelets. Results from studies with the antiplatelet compound ajoene. 191 78

Calpactin, or calpactin heavy chain (p36), reconstitute secretion in digitonin-permeabilized adrenal chromaffin cells after a reduction in their secretory potential resulting from the loss of cytosolic components. We have characterized the stimulatory effect of p36, which resulted in an increase in both the extent and the rate of exocytosis. A mixture of other annexins (p70 and p32) did not have any effect on secretion at similar or greater concentrations than p36. Controlled proteolysis of p36 using chymotrypsin was carried out, and the 33,000 molecular weight core and 3000 molecular weight tail peptide isolated. In contrast to p36, p33 had no effect on exocytosis, even at high calcium concentrations. The N-terminal tail peptide and a synthetic peptide based on the tail of p36 [Ac-calpactin-(1-15)-NH2] had no effect on endogenous secretion, or secretion stimulated by exogenous p36. The results show that both the tail and core domains are required for p36 to stimulate exocytosis. The tail domain is unlikely to be required for interaction with cellular components but probably has a regulatory effect on the core domain. Endogenous secretion and the stimulatory effect of p36 were markedly inhibited by depletion of ATP. The ATP requirement for p36 action was not due to a requirement for phosphorylation by protein kinase C (PKC), since the PKC inhibitor staurosporine partially inhibited endogenous secretion but did not affect the stimulation of exocytosis due to exogenous p36.
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PMID:The stimulatory effect of calpactin (annexin II) on calcium-dependent exocytosis in chromaffin cells: requirement for both the N-terminal and core domains of p36 and ATP. 214 64

The complete primary structure of a bovine-brain-derived inhibitor of protein kinase C has been established. Fragments of the purified protein were obtained by cleavage with cyanogen bromide, Staphylococcus aureus V8 protease, trypsin and chymotrypsin. Subsequent analysis of the resulting fragments by fast-atom-bombardment mass spectrometry and Edman degradation revealed a calculated molecular mass of 11,779 Da with the following 107-amino-acid sequence: [sequence: see text] This inhibitor does not share significant primary structural identity with any other known protein.
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PMID:Amino acid sequence of a 12-kDa inhibitor of protein kinase C. 191 53

Two intrinsic proteins of bovine lens membranes with apparent relative molecular masses (Mr, app) of 26,000 and 18,000 were phosphorylated in intact membranes by protein kinase C prepared from either bovine brain or lens. The kinase preparations exhibited histone H1 phosphorylation dependent on calcium and phospholipid but not on cAMP. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis of the lens membranes showed a major band at Mr, app = 26,000 (identified as MP26, the main intrinsic protein of lens fiber cells), an intermediate band at Mr, app = 18,000 and several minor bands. Autoradiography of complete assay mixture containing protein kinase C, calcium, magnesium and [gamma-32P]ATP showed major bands at Mr, app = 18,000 and 26,000. Several lines of evidence indicated that the label at Mr, app = 26,000 was associated with MP26, a protein which has been found in lens junctions and which may form cell-cell channels. Treatment of the phosphorylated membranes with chymotrypsin and V8 protease cleaved the major band at Mr, app = 26,000 to fragments of Mr, app .= 22,000 and 24,000. Label was not detected in the resulting Mr, app = 22,000 peptide, but the Mr, app = 24,000 peptide was found to be labeled. Phosphoamino acid analysis of MP26 indicated that approximately 75% of the label was on phosphoserine and 25% was on phosphothreonine. No label was found on phosphotyrosine. These results differ from those reported for cAMP-dependent phosphorylation of lens proteins. Phosphorylation by protein kinase C may account for some of the labeling of MP26 detected in vivo.
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PMID:Phosphorylation of lens intrinsic membrane proteins by protein kinase C. 242 29

Purified phospholamban isolated from canine cardiac sarcoplasmic reticulum vesicles was subjected to proteolysis and peptide mapping to localize the different sites of phosphorylation on the protein and to gain further information on its subunit structure. Five different proteases (trypsin, papain, chymotrypsin, elastase, and Pronase) degraded the oligomeric 27-kDa phosphoprotein into a major 21-22-kDa protease-resistant fragment. No 32P was retained by this protease-resistant fragment, regardless of whether phospholamban had been phosphorylated by cAMP-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase, or protein kinase C. Phosphoamino acid analysis and thin-layer electrophoresis of liberated phosphopeptides revealed that 1 threonine and 2 serine residues were phosphorylated in phospholamban and that 1 of these serine residues and the threonine residue were in close proximity. Only serine was phosphorylated by cAMP-dependent protein kinase, whereas Ca2+-calmodulin-dependent protein kinase phosphorylated exclusively threonine. The results demonstrate that phospholamban has a large protease-resistant domain and a smaller protease-sensitive domain, the latter of which contains all of the sites of phosphorylation. The 21-22-kDa protease-resistant domain, although devoid of incorporated 32P, was completely dissociated into identical lower molecular weight subunits by boiling in sodium dodecyl sulfate, suggesting that this region of the molecule promotes the relatively strong interactions that hold the subunits together. The data presented lend further support for a model of phospholamban structure in which several identical low molecular weight subunits are noncovalently bound to one another, each containing one site of phosphorylation for cAMP-dependent protein kinase and another site of phosphorylation for Ca2+/calmodulin-dependent protein kinase.
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PMID:Proteolytic cleavage of phospholamban purified from canine cardiac sarcoplasmic reticulum vesicles. Generation of a low resolution model of phospholamban structure. 300 93

Phosphorylation of human fibrinogen in vitro by incubation with [gamma-32P]ATP and protein kinase C purified from pig spleen, led to incorporation of [32P]phosphate at serine residues located in the A alpha-chain. In order to identify the residues that were phosphorylated, the A alpha-chain of fibrinogen was isolated and subjected to consecutive cleavage by cyanogen bromide, trypsin, and chymotrypsin. The resulting radioactive phosphopeptides were purified by gel chromatography and high-performance liquid chromatography using a reversed-phase column. Subsequent amino acid analysis and manual Edman degradation of the purified phosphopeptides revealed that Ser557, Ser558, Ser559, and Ser599 were phosphorylated. These serine residues are located in the carboxy-terminal part of the A alpha-chain. This region also contains lysine residues participating in the cross-linking of fibrin and, possibly, a site involved in the binding of fibrinogen to receptors on platelets. In addition, peptides derived from the middle section of the polypeptide chain were found to contain [32P]phosphate; in these cases, however, the exact localization of the phosphate could not be determined, due to the low yield of radioactivity. Two glutamine residues, Gln328 and Gln366, in this portion of the A alpha-chain take part in the cross-linking of fibrin.
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PMID:Phosphorylation of human fibrinogen in vitro with protein kinase C: characterization of the phosphorylated sites. 310 98

The addition of the tumor promoting phorbol ester 12-O-tetradecanoyl phorbol 13-acetate to intact human red blood cells activates protein kinase C and stimulates the phosphorylation of the membrane skeletal proteins band 4.1 and band 4.9 as well as two proteins of molecular mass 115 and 110 kDa. We show that 12-O-tetradecanoyl phorbol 13-acetate promotes the association of cytosolic protein kinase C with the red cell membrane and that the enzyme is present on ghost membranes but is largely absent from inside-out vesicles. We show that micromolar Ca2+ added to ghosts also promotes the phosphorylation of band 4.1 and the approximately 100-kDa proteins, a reaction which has not been described previously. Digestion and extraction studies show that the 100-kDa proteins are unrelated to band 3 since they are absent from NaOH stripped membranes, but are found in Triton-prepared cytoskeletons. Digestion of intact red cells with chymotrypsin or neuraminidase, which attack principally band 3 and glycophorin, respectively, markedly inhibits protein kinase C phosphorylation of band 4.1 in red cells and ghosts and of the 100-kDa proteins in ghosts. These enzymes have no effect upon the activity of the Ca2+-activated phosphorylation reaction, suggesting that it does not involve protein kinase C. These results shed light on two phosphorylation reactions which act exclusively on red cell membrane skeletal proteins. Our findings suggest that digestion of the integral membrane proteins band 3 and glycophorin, the principal targets of external protease digestion, affects the activity or specificity of protein kinase C. Finally we have described two apparently novel approximately 100-kDa phosphorylated proteins which are components of Triton-prepared red cell membrane skeletons.
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PMID:Phorbol ester- and Ca2+-dependent phosphorylation of human red cell membrane skeletal proteins. 371 Nov 3


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