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)

To test the role of protein kinase C in the control of pulmonary vascular tone and reactivity, we examined the effects of the activators, phorbol 12-myristate-13-acetate (PMA), mezerein, and 1,2-dioctanyl-rac-glycerol (1,2-DOG), in rat isolated large pulmonary arteries and salt solution-perfused lungs. PMA (500 nM) and mezerein (100 nM) induced slow, sustained contractions of isolated pulmonary arteries. These contractions were not inhibited by nifedipine (1 microM), the intracellular Ca2+ blocker TMB-8 (50 microM), a 0 Ca2+ and EGTA (2 mM) bath, or endothelial denudation. They were reduced by amiloride (500 microM), an inhibitor of Na+/H+ exchange, and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7); (50 microM), an inhibitor of protein kinase C. PMA caused concentration-dependent (5 to 500 nM) potentiation of KCl, serotonin, and A23187 contractions of isolated pulmonary arteries. The effect of PMA on norepinephrine contraction was dependent on both concentration and time. Whereas PMA potentiated norepinephrine contraction after 5 min, it inhibited the response after 60 min. PMA and mezerein also caused concentration-dependent (0.5 to 500 nM) vasoconstriction in isolated lungs. The PMA vasoconstriction was unaltered by meclofenamate (1.6 microM) but was attenuated by nifedipine (1 microM). Low concentrations of PMA (5 nM) and 1,2-DOG (50 microM) potentiated both hypoxic and KCl vasoconstriction in isolated lungs. In contrast, the hypoxic and KCl responses were blunted by H-7 (30 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protein kinase C influences rat pulmonary vascular reactivity. 210 13

Signaling via the alpha-beta T cell Ag receptor (Ti)-CD3 complex is a complicated event that implicates several protein kinases, most notably protein kinase C (PKC). We have recently identified a serine kinase in T lymphocytes with the following characteristics: molecular mass 43 kDa, in vitro substrate affinity for microtubule associated protein 2 (MAP-2) with a preference for Mn2+ during the catalytic reaction, and elution from DEAE resin over a salt range 100 to 200 mM NaCl. This kinase is activated in a rapidly reversible fashion during ligation of CD3/Ti by a process which involves prior phosphorylation; in vitro exposure of activated 43-kDa MAP-2 kinase (MAP-K) to an immobilized phosphatase abrogated its kinase activity. We now show that a MAP-2K response could also be obtained during treatment with mAb to Ti and the specific PKC agonist, PMA. Although the kinetics of the former response was rapidly reversible, PMA elicited a more prolonged response. The dose responsiveness for PMA was similar to the requirements for PKC activation in intact lymphocytes. Moreover, as with PKC, we found that the CD3-induced MAP-2K response could be further enhanced by using a second layer cross-linking antibody. The specificity of CD3/Ti in the Jurkat cell response is demonstrated by the fact that OKT-11(CD2) and anti-CD4 mAb did not stimulate a MAP-2K response. It was also not possible to elicit a response in a Jurkat cell mutant that lacks surface expression of CD3 and Ti. The specificity of PKC in these events was further explored with the cell permeant diacylglycerol, 1-oleoyl-2-acetylglycerol, and the nonagonist phorbol ester, 4 alpha-phorbol 12,13-didecanoate: whereas the former was an effective inducer of the MAP-2K response, the latter failed to yield any stimulation. Prior exposure of Jurkat cells to 100 mM PMA for 24 h eliminated greater than 60% of the MAP-2K response during anti-CD3 treatment. This response could also be inhibited in dose-dependent fashion by prior treatment of Jurkat cells with the potent PKC inhibitor 1-(5-isoquinolinesulfonyl) 2-methylpiperazine dihydrochloride. Although a Ca2(+)-ionophore failed to synergize with PMA at inducing a MAP-2K response, depletion of extracellular Ca2+ by EGTA abrogated anti-CD3 responsiveness. The events culminating in MAP-2K activation were slightly inhibited in the presence of cholera toxin but not pertussis toxin.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Stimulation of MAP-2 kinase activity in T lymphocytes by anti-CD3 or anti-Ti monoclonal antibody is partially dependent on protein kinase C. 215 31

The kinetics of phosphorylation of an integral membrane enzyme, Na+/K(+)-ATPase, by calcium- and phospholipid-dependent protein kinase C (PKC) were characterized in vitro. The phosphorylation by PKC occurred on the catalytic alpha-subunit of Na+/K(+)-ATPase in preparations of purified enzyme from dog kidney and duck salt-gland and in preparations of duck salt-gland microsomes. The phosphorylation required calcium (Ka approximately 1.0 microM) and was stimulated by tumor-promoting phorbol ester (12-O-tetradecanoylphorbol 13-acetate) in the presence of a low concentration of calcium (0.1 microM). PKC phosphorylation of Na+/K(+)-ATPase was rapid and plateaued within 30 min. The apparent Km of PKC for Na+/K(+)-ATPase as a substrate was 0.5 microM for dog kidney enzyme and 0.3 microM for duck salt-gland enzyme. Apparent substrate inhibition of PKC activity was observed at concentrations of purified salt-gland Na+/K(+)-ATPase greater than 1.0 microM. Phosphorylation of purified kidney and salt-gland Na+/K+ ATPases occurred at both serine and threonine residues. The 32P-phosphopeptide pattern on 15% sodium dodecyl sulfate-polyacrylamide gel electrophoresis after hydroxylamine cleavage of pure 32P-phosphorylated alpha subunit was the same for the two sources of enzyme, which suggests that the phosphorylation sites are similar. The results indicate that Na+/K(+)-ATPase may serve as a substrate for PKC phosphorylation in intact cells and that the Na+/K(+)-ATPase could be a useful in vitro model substrate for PKC interaction with integral membrane proteins.
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PMID:Kinetics of phosphorylation of Na+/K(+)-ATPase by protein kinase C. 215 96

Calcium, adenosine 3',5'-cyclic monophosphate (cAMP), and guanosine 3',5'-cyclic monophosphate (cGMP) can regulate the same or different ion transport processes within an epithelium, presumably via independent protein phosphorylation mechanisms. Because there have been few detailed studies characterizing these processes in epithelia, we examined the distribution of Ca-, cAMP-, and cGMP-specific protein kinases and substrates in vitro in a homogenous salt-absorbing epithelium, the winter flounder intestine. In this tissue cGMP and Ca inhibit Na-K-2Cl cotransport, cAMP increases anion permeability, and phorbol esters do not affect ion transport. The Ca-specific kinases are calmodulin (CaM) dependent. The tissue possesses type III Ca-CaM protein kinase and its specific substrate elongation factor 2 and type II but not type I Ca-CaM kinase. Addition of phosphatidylserine (PS) and Ca to crude or DEAE-cellulose-purified cytosol neither increased the phosphorylation of exogenous histone H1 substrate nor that of any endogenous substrates. Although these suggest the absence of Ca-phospholipid-dependent kinase (PKC), the cytosol has a 78-kDa protein recognizable by a highly specific polyclonal sheep antibody to rat brain PKC. Both the particulate and cytosolic fractions possess cAMP-specific binding proteins and cAMP-specific phosphoprotein substrates. The particulate fraction cAMP-binding proteins are of molecular mass 50 kDa (pI 5.2) and 48 kDa with multiple isoforms (pI 5.6-6.2); these proteins generate different peptide maps. The cytosol chiefly contains a 50-kDa (pI 5.2) cAMP binding protein that is similar to the particulate 50-kDa protein on peptide mapping. The flounder cAMP binding proteins have the same pI but lower molecular mass and different peptide profiles than the rat brain RII (54/52 kDa) and RI (50 kDa) cAMP regulatory proteins. The cGMP-specific protein kinase was less prominent, very low levels of cGMP-specific binding proteins being detected either by equilibrium binding or by photoaffinity labeling. A prominent kinase substrate in homogenates is a 50-kDa protein, the phosphorylation of which is increased by Ca and cGMP but decreased by cAMP. When intact tissue was prelabeled with 32Pi and then exposed to cGMP, the phosphorylation of a number of substrates including that of a 50-kDa protein was increased. In summary, the flounder intestine possesses the necessary protein phosphorylation mechanisms to account for the regulation of its ion transport processes by second messengers.
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PMID:Second messenger-specific protein kinases in a salt-absorbing intestinal epithelium. 215 31

Multiple second messengers, presumably acting via protein phosphorylation mechanisms, regulate flounder intestinal ion transport. We recently reported [C. Toskulkao, N. T. Nash, K. Leach, and M. C. Rao. Am. J. Physiol. 258 (Cell Physiol. 27): C879-C888, 1990] that this tissue possesses adenosine 3',5'-cyclic monophosphate (cAMP)- and guanosine 3',5'-cyclic monophosphate (cGMP)-specific protein kinases, types II and III Ca-calmodulin kinases, and very low levels of protein kinase C. These results correlate with ion transport studies in which cGMP and Ca were shown to inhibit salt absorption, cAMP to increase anion permeability, and phorbol esters to have no effect. In the present study we characterized in detail a 50-kDa protein the phosphorylation of which is regulated by more than one second messenger. The 50-kDa (pI 5.2) phosphoprotein is present in both the cytosol (50 kDa-C) and particulate (50 kDa-P) fractions and appears to be regulated by Ca, cAMP, and cGMP. Although the pI and Mr of the regulated proteins are identical, there are differences in the regulation of 50 kDa-P and 50 kDa-C. The phosphorylation of 50 kDa-P is high in the basal state, and Ca and cGMP enhance this. cAMP has a biphasic effect, increasing it at low and decreasing it at high protein concentrations. The isoquinoline derivatives H-8 [50% effective dose (ED50) approximately 2.3 microM] and H-7 (ED50 approximately 45 microM) inhibit basal 50 kDa-P phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of a 50-kDa Ca-, cAMP-, and cGMP-dependent epithelial phosphoprotein as a cAMP regulatory protein. 215 32

A protein of Mr approximately 120,000, related to the human erythrocyte membrane skeletal protein alpha-adducin, has been identified by immunological criteria in human fibroblasts. Using similar methods, beta-adducin (an Mr approximately 110,000 protein that forms a dimeric complex with alpha-adducin in the erythrocyte) is not present in fibroblasts. Subcellular distribution studies reveal that fibroblast alpha-adducin is largely associated with the particulate fraction and is most effectively solubilized from that fraction by a combination of nonionic detergent and high salt. Immunocytochemistry of quiescent fibroblasts shows that alpha-adducin is clustered in large perinuclear arrays that may correspond to vesicular structures; weak staining was also found in the sub-plasma membrane region. As in erythrocytes, the phosphorylation of fibroblast alpha-adducin is elevated on exposure of cells to phorbol esters that activate protein kinase C (PK-C). In addition, various mitogens such as serum, bradykinin and vasopressin also stimulate alpha-adducin phosphorylation by a PK-C-dependent pathway. The elevation in alpha-adducin phosphorylation is maintained for up to 30 min after mitogen addition. Peptide maps of phospho-alpha-adducin from both fibroblasts and erythrocytes after PK-C-mediated phosphorylation showed multiple phosphorylated peptides but with dissimilar migration patterns, suggesting divergence of structure around the phosphorylation sites. Adducin appears to play an important role in the regulation of spectrin-actin interactions in the red cell and may play a role in cytoskeletal function in the fibroblasts.
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PMID:Identification and protein kinase C-dependent phosphorylation of alpha-adducin in human fibroblasts. 219 89

Angiotensin II (ang II) induces c-fos gene expression in part via a protein kinase C-dependent mechanism in cultured vascular smooth muscle cells (VSMC). However, little is known about the mechanisms by which protein kinase C regulates nuclear functions. We examined the ability of ang II to phosphorylate nuclear lamina proteins in VSMC and the possibility that protein kinase C is involved in these putative phosphorylation events. Ang II stimulated the phosphorylation of Triton X-100- and high salt-insoluble nuclear envelope proteins with molecular weights of 70,000, 67,000, and 60,000. These proteins were identified as lamins A, B, and C, respectively, based on their mobilities on two-dimensional gel electrophoresis and interaction with antibodies to lamins as detected by immunoblot analyses. After a 2-min delay, phosphorylation levels of lamins increased, peaked at 20-30 min, and were sustained for at least 60 min after ang II stimulation. The threshold, half-maximal, and maximal concentrations of ang II which induced phosphorylation of lamins were 0.1, 0.5-1, and 100 nM, respectively. Phorbol 12-myristate 13-acetate also induced these reactions, whereas ionomycin did not. Down-regulation of protein kinase C by prolonged treatment with phorbol 12,13-dibutyrate attenuated ang II-induced phosphorylation of lamins. In vitro phosphorylation of nuclear envelope proteins by protein kinase C revealed that lamins served as substrates for this enzyme. These results indicate that ang II induces phosphorylation of lamins in cultured VSMC and suggest that protein kinase C is either directly or indirectly involved in these reactions. The results raise the possibility that phosphorylation of nuclear proteins is one of the important steps by which the protein kinase C signaling pathway regulates agonist-induced nuclear events.
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PMID:Angiotensin II stimulates phosphorylation of nuclear lamins via a protein kinase C-dependent mechanism in cultured vascular smooth muscle cells. 229 7

CI-949 [5-methyl-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H- indole-2- carboxamide, L-arginine salt] inhibits human neutrophil activation in response to stimuli which promote calcium mobilization or calcium influx. This report further examines the effect of CI-949 on phosphoinositide-dependent stimulus-response coupling. At 100 microM, CI-949 had no inhibitory effect on human neutrophil phospholipase C or protein kinase C. In contrast, CI-949 inhibited FMLP-stimulated intracellular calcium mobilization with an IC50 of 8.4 microM. The compound was also a potent calmodulin antagonist, inhibiting calmodulin-dependent phosphodiesterase activity with an IC50 of 31.0 microM. The calmodulin antagonist activity of CI-949 was confirmed by fluorescence spectroscopy. These results demonstrate that CI-949 may function through inhibition of calcium- and calmodulin-dependent signal transduction processes.
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PMID:Inhibition of human neutrophil activation by the allergic mediator release inhibitor, CI-949: mechanism of inhibitory activity. 232 55

Binding of TRH to specific cell surface receptors on clonal GH4C1 cells is followed within 10 min by receptor sequestration and over 24 h by receptor down-regulation. These experiments were designed to determine if TRH-activated second messenger systems are responsible for changes in receptor localization or number. BAY K8644 and A23187, which increase intracellular calcium, alone or together with 12-O-tetradecanoyl phorbol acetate (TPA), which activates protein kinase C, did not appear to internalize TRH receptors. Drug treatment did not alter the rate of [3H]MeTRH association or internalization, determined by resistance to an acid/salt wash, or the amount of [3H]MeTRH able to bind at 0 C, where only surface receptors are accessible. TPA (0-100 nM) alone or in combination with BAY K8644 or A23187, also failed to change receptor number or affinity after 48 h when TRH caused a 75% decrease in the density of specific binding sites. Chlordiazepoxide has been reported antagonize TRH binding and TRH-induced phospholipid breakdown. Chlordiazepoxide shifted the dose-response curves for TRH stimulation of PRL release and synthesis to the right, and did not change PRL release alone. The affinity of receptors for chlordiazepoxide was not affected by a nonhydrolyzable analog of GTP whereas affinity for TRH was decreased; these properties are consistent with the classification of chlordiazepoxide as a competitive antagonist. Several experiments tested whether chlordiazepoxide would cause receptor internalization and down-regulation. Chlordiazepoxide did not appear to internalize TRH receptors, because TRH-binding sites became available rapidly and at the same rate after they had been saturated with chlordiazepoxide at 0 or 37 C.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pituitary thyrotropin-releasing hormone (TRH) receptors: effects of TRH, drugs mimicking TRH action, and chlordiazepoxide. 248 18

Previous studies have shown that erythrocytes from the Milan hypertensive strain of rats (MHS) differ from erythrocytes from the control normotensive strain (MNS). These differences are determined within the stem cells, are genetically associated with the development of hypertension, and are similar to those found between the tubular cells of the two strains. Moreover they seem to be dependent upon the presence of the membrane skeleton proteins. In this paper we describe our studies aimed at identifying some precise protein difference between the membrane skeletons of the two strains, which may cause the cellular differences described above. Milan hypertensive strain and MNS rats were immunized with ghost or membrane skeleton extracts prepared from the other or their own strains. Only MHS rats immunized with MNS ghost or membrane skeleton extracts produced an antibody against a 105 KD protein in about 95% of the animals. This protein has been identified with the recently described cytoskeletal protein adducin on the following bases: the protein binds calmodulin (CaM) and protein kinase C (PKc) in a Ca2+ dependent way. It also binds phosphatidylserine, is the substrate of exogenous PKc, and finally it is purified by high salt extraction of Triton-X100 insoluble erythrocyte cytoskeletons followed by affinity chromatography on CaM-sepharose. Using this antibody the isolation from a mouse spleen library, the characterization and sequencing of a partial cDNA clone coding for this protein has been carried out. In conclusion adducin may be considered a very useful tool to test the hypothesis that the cellular differences between MHS and MNS may be caused by a difference in a membrane skeleton protein.
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PMID:Erythrocyte adducin differential properties in the normotensive and hypertensive rats of the Milan strain. Characterization of spleen adducin m-RNA. 270 90


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