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)

Most of the currently available calmodulin (CaM) antagonists inhibit the actions of CaM by binding directly to it. These CaM-binding drugs tend to be relatively nonselective, because they inhibit the interaction of CaM with most, if not all, of its target enzymes. In order to develop more selective CaM antagonists, we synthesized covalent adducts of CaM and several drugs, including chlorpromazine (CPZ), fluphenazine-N-mustard (FNM), and phenoxybenzamine (PBZ), and examined the effects of these adducts on various CaM and Ca2(+)-dependent enzymes. One of the adducts (CPZ-CaM) selectively inhibited the CaM-induced activation of phosphodiesterase and myosin light chain kinase, without affecting the basal activity of either enzyme. The inhibition of these enzymes by CPZ-CaM was competitive with respect to CaM. CPZ-CaM did not inhibit CaM-sensitive Ca2(+)-ATPase or CaM-dependent protein kinase or the CaM-insensitive enzyme protein kinase C. The FNM-CaM and PBZ-CaM adducts did not inhibit the effects of CaM on any of the enzymes, but they selectively activated two of the enzymes; FNM-CaM slightly activated the CaM-dependent protein kinase, and PBZ-CaM slightly activated phosphodiesterase. These results show that certain covalently linked drug-CaM adducts can differentially inhibit or activate various CaM-sensitive enzymes, and they provide further evidence that it may be possible to develop new classes of CaM antagonists that are directed against the CaM recognition sites on CaM-sensitive enzymes.
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PMID:Differential inhibition of calcium-dependent and calmodulin-dependent enzymes by drug-calmodulin adducts. 214 88

A newly synthesized isoquinolinesulfonamide, H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide), was shown to have a potent and selective inhibitory action against cyclic AMP-dependent protein kinase (protein kinase A), with an inhibition constant of 0.048 +/- 0.008 microM. H-89 exhibited weak inhibitory action against other kinases and Ki values of the compound for these kinases, including cGMP-dependent protein kinase (protein kinase G), Ca2+/phospholipid-dependent protein kinase (protein kinase C), casein kinase I and II, myosin light chain kinase, and Ca2+/calmodulin-dependent protein kinase II were 0.48 +/- 0.13, 31.7 +/- 15.9, 38.3 +/- 6.0, 136.7 +/- 17.0, 28.3 +/- 17.5, and 29.7 +/- 8.1 microM, respectively. Kinetic analysis indicated that H-89 inhibits protein kinase A, in competitive fashion against ATP. To examine the role of protein kinase A in neurite outgrowth of PC12 cells, H-89 was applied along with nerve growth factor (NGF), forskolin, or dibutyryl cAMP. Pretreatment with H-89 led to a dose-dependent inhibition of the forskolin-induced protein phosphorylation, with no decrease in intracellular cyclic AMP levels in PC12D cells, and the NGF-induced protein phosphorylation was not not inhibited. H-89 also significantly inhibited the forskolin-induced neurite outgrowth from PC12D cells. This inhibition also occurred when H-89 was added before the addition of dibutyryl cAMP. Pretreatment of PC12D cells with H-89 (30 microM) inhibited significantly cAMP-dependent histone IIb phosphorylation activity in cell lysates but did not affect other protein phosphorylation activity such as cGMP-dependent histone IIb phosphorylation activity, Ca2+/phospholipid-dependent histone IIIs phosphorylation activity, Ca2+/calmodulin-dependent myosin light chain phosphorylation activity, and alpha-casein phosphorylation activity. However, this protein kinase A inhibitor did not inhibit the NGF-induced neurite outgrowth from PC12D cells. Thus, the forskolin- and dibutyryl cAMP-induced neurite outgrowth is apparently mediated by protein kinase A while the NGF-induced neurite outgrowth is mediated by a protein kinase A-independent pathway.
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PMID:Inhibition of forskolin-induced neurite outgrowth and protein phosphorylation by a newly synthesized selective inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), of PC12D pheochromocytoma cells. 215 66

Calponin isolated from chicken gizzard smooth muscle inhibits the actin-activated MgATPase activity of smooth muscle myosin in a reconstituted system composed of contractile and regulatory proteins. ATPase inhibition is not due to inhibition of myosin phosphorylation since, at calponin concentrations sufficient to cause maximal ATPase inhibition, myosin phosphorylation was unaffected. Furthermore, calponin inhibited the actin-activated MgATPase of fully phosphorylated or thiophosphorylated myosin. Although calponin is a Ca2(+)-binding protein, inhibition did not require Ca2+. Furthermore, although calponin also binds to tropomyosin, ATPase inhibition was not dependent on the presence of tropomyosin. Calponin was phosphorylated in vitro by protein kinase C and Ca2+/calmodulin-dependent protein kinase II, but not by cAMP- or cGMP-dependent protein kinases, or myosin light chain kinase. Phosphorylation of calponin by either kinase resulted in loss of its ability to inhibit the actomyosin ATPase. The phosphorylated protein retained calmodulin and tropomyosin binding capabilities, but actin binding was greatly reduced. The calponin-actin interaction, therefore, appears to be responsible for inhibition of the actomyosin ATPase. These observations suggest that calponin may be involved in regulating actin-myosin interaction and, therefore, the contractile state of smooth muscle. Calponin function in turn is regulated by Ca2(+)-dependent phosphorylation.
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PMID:Smooth muscle calponin. Inhibition of actomyosin MgATPase and regulation by phosphorylation. 216 34

This study investigates the role of protein kinase C and of myosin light chain kinase in mediating platelet hyperresponsiveness in spontaneously hypertensive rats (SHR). For this purpose, 32P-labeled washed platelets of both SHR and normotensive controls Wistar-Kyoto (WKY) were challenged either with a receptor-mediated agonist (thrombin) or with direct activators of myosin light chain kinase and protein kinase C. Such enzymatic activities were assessed by measuring changes in 32P-labeling of their respective target proteins, namely myosin light chain (20 KDa) and the 47 KDa protein. In resting platelets, the patterns of protein phosphorylation were similar between SHR and WKY, suggesting that the two cell types were in a comparable quiescent status. By contrast, in both dose-response and time-course studies, thrombin promoted a significantly greater phosphorylation of the 20- and 47 KDa proteins in platelets of SHR compared with that for WKY. Sensitivity of myosin light chain kinase to the calcium ionophore A23187 and of protein kinase C to both phorbol ester and dioctanoylglycerol was apparently not different between the two cell types. The data indicate that the exaggerated thrombin-induced protein phosphorylation observed for platelets of SHR is not linked to alterations in protein kinase C and/or myosin light chain kinase per se. These results therefore suggest that platelet hyperresponsiveness in SHR is likely to be related, at least in part, to abnormalities in receptor-mediated transmembrane signalling.
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PMID:Receptor-dependent and -independent protein phosphorylation in platelets of spontaneously hypertensive rats. 217 66

MDL 27,032 [4-propyl-5-(4-pyridinyl)-2(3H)-oxazolone] is a novel vasodilator whose mechanism of action has not been elucidated. We investigated whether smooth muscle relaxation by MDL 27,032, in vitro, may involve an alteration in the activity of protein kinase C, cyclic AMP (cAMP)-dependent protein kinase or myosin light chain kinase by investigating the effects of MDL 27,032 on cyclic nucleotide phosphodiesterases (PDEs) and protein kinase activities. Strips of dog femoral artery or saphenous vein contracted with phorbol 12-myristate 13-acetate (PMA) were relaxed by 100 microM concentrations of MDL 27,032, as well as by other known inhibitors of PDEs [3-isobutyl-1-methylxanthine and papaverine], myosin light chain kinase (W-7) and protein kinase C (H-7 and polymyxin B). In contrast to 3-isobutyl-1-methylxanthine and papaverine, MDL 27,032 was either inactive or weak as an inhibitor of purified PDE types I, II, IVa and IVb. Similarly, it was a weak inhibitor of myosin light chain kinase. However, MDL 27,032 was a significantly more potent inhibitor of protein kinase C and cAMP-dependent protein kinase in cytosolic extracts of dog vein. Kinetic experiments utilizing purified rat brain protein kinase C revealed that inhibition with MDL 27,032 was competitive with Mg(++)-ATP (Ki 24 microM) and noncompetitive with phospholipid, diacylglycerol, PMA, calcium or substrate proteins. Inhibition of the catalytic subunit of cAMP-dependent protein kinase was also competitive with Mg(++)-ATP (Ki 14.3 microM). Similar results were obtained with MDL 27,032 and H-7 on both enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:MDL 27,032 [4-propyl-5-(4-pyridinyl)-2(3H)-oxazolone], an active site-directed inhibitor of protein kinase C and cyclic AMP-dependent protein kinase that relaxes vascular smooth muscle. 217 6

We examined the tyrosine kinase inhibitor erbstatin and several derivatives for their ability to inhibit serine/threonine protein kinases in vitro. Erbstatin was found to inhibit protein kinase C (PKC) with an IC50 of 19.8 +/- 3.2 microM. A trihydroxy derivative of erbstatin inhibited PKC with similar potency, whereas the corresponding methoxy derivatives were inactive. Inhibition by erbstatin was competitive with ATP (Ki = 11.0 +/- 2.3 microM) and non-competitive with the phosphate acceptor, either histone or the synthetic peptide kemptide. Action of erbstatin at the catalytic site of PKC was further indicated by the findings that it inhibited the catalytic fragment of PKC but did not inhibit the interaction of phorbol ester with the intact enzyme. Erbstatin had a similar potency against three PKC isozymes (alpha, beta, and gamma) examined. In addition, erbstatin was found to inhibit other serine/threonine kinases (assayed at their Km for ATP). The greatest potency was observed versus the cyclic nucleotide-dependent kinases, while lower potency was seen versus myosin light chain kinase. These observations are discussed in terms of the structure and kinetic properties of PKC and the epidermal growth factor receptor tyrosine kinase.
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PMID:Inhibition of protein kinase C by the tyrosine kinase inhibitor erbstatin. 224 40

Stretching of porcine carotid arterial muscle increased the phosphorylation of the 20 kDa myosin light chain from 0.23 to 0.68 mol [32P]phosphate/mol light chain, whereas stretching of phorbol dibutyrate treated muscle increased the phosphorylation from 0.30 to 0.91 mol/mol. Two-dimensional gel electrophoresis followed by two-dimensional tryptic phosphopeptide mapping was used to identify the enzyme involved in the stretch-induced phosphorylation. Quantitation of the [32P]phosphate content of the peptides revealed considerable light chain phosphorylation by protein kinase C only in the phorbol dibutyrate treated arterial muscle, whereas most of the light chain phosphorylation was attributable to myosin light chain kinase. Upon stretch of either the untreated or treated muscle, the total increment in [32P]phosphate incorporation into the light chain could be accounted for by peptides characteristic for myosin light chain kinase catalyzed phosphorylation, demonstrating that the stretch-induced phosphorylation is caused by this enzyme exclusively.
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PMID:Stretch activates myosin light chain kinase in arterial smooth muscle. 225 11

In this study, we investigated the possible involvement of protein kinase C in the inhibitory effect of neuropeptide Y (NPY) on the electrical stimulation-induced release of radioactivity from mouse atria incubated with [3H]-noradrenaline. The protein kinase C activators, phorbol dibutyrate (PDB, 0.001-1 mumol/l) and phorbol myristate acetate (PMA, 0.001-1 mumol/l), increased the release of noradrenaline in a concentration-dependent manner. Interestingly, the maximum effect on noradrenaline release was significantly greater for phorbol dibutyrate compared to phorbol myristate acetate. The enhancement produced by both phorbol esters was significantly reduced by the protein kinase C inhibitor, K-252a (1 mumol/l). In the presence of the concentration of either phorbol ester (PMA, 0.1 mumol/l, PDB 1 mumol/l), that was supramaximal for increasing the release of noradrenaline, NPY (0.3 mumol/l) significantly inhibited the release of noradrenaline. Moreover, in the presence of the protein kinase C inhibitors, K-252a (1 mumol/l) or polymyxin B (70 mumol/l), NPY (0.3 mumol/l) also significantly inhibited the release of noradrenaline. Therefore, it is concluded that protein kinase C is not involved in the prejunctional inhibitory effect of NPY on noradrenaline release in the mouse atria. Furthermore, since K-252a also inhibits cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase and myosin light chain kinase, it is likely that these kinases are also not involved in the inhibitory mechanism of NPY.
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PMID:Inhibition of noradrenaline release by neuropeptide Y does not involve protein kinase C in mouse atria. 225 91

Endothelin-1 contracts porcine carotid arterial smooth muscle with an ED50 of 10 nM. Contraction is associated with phosphorylation of the 20,000 dalton-regulatory light chain subunits of vascular myosin. Phosphopeptide mapping of light chains isolated from 32PO4-loaded muscle strips stimulated by endothelin-1 (5 x 10(-8) M) and comparison with maps generated from light chains phosphorylated in vitro or muscles stimulated with KCl (110 mM) or angiotensin-II (5 x 10(-8) M) indicates that Ca2(+)-calmodulin activation of myosin light chain kinase is a biochemical pathway stimulated by all three agonists. However, a small amount of phosphate (17%) was detected in a light chain peptide phosphorylated by protein kinase C. Endothelin-1 also stimulated phosphorylation of the thin filament protein, caldesmon, (from 0.35 mol PO4/mol caldesmon to 0.52 mol PO4/mol). Collectively, these results provide evidence that the effects of endothelin-1 on force generation and maintenance in vascular muscle may be dependent upon myosin light chain phosphorylation by Ca2+ calmodulin--requiring myosin light chain kinase and upon a thin filament mechanism that is modulated by phosphorylation of caldesmon.
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PMID:Myosin light chain and caldesmon phosphorylation in arterial muscle stimulated with endothelin-1. 228 Apr 12

Smooth muscle contractile agents cause large increases in crossbridge phosphorylation (Mp) and cycling rates resulting in the rapid development of stress (force/muscle cross-sectional area). Despite temporal declines in Mp and cycling during continued activation, stress is maintained at high levels. This observation led to several different hypotheses describing the regulation of steady-state stress. One proposal is that protein kinase C regulates stress maintenance, whereas another invokes a steady-state dependence on Ca+(+)-calmodulin-dependent myosin light chain kinase. The aim of this study was to investigate the mechanism of stress-maintenance by analyzing the inhibitory efficacy of a protein kinase C inhibitor, H-7 [1-(5-isoquinolinesulfonyl)-2-methylpiperizine], on steady-state values of stress, Mp and crossbridge cycling in rabbit renal and femoral arteries. H-7 effectively inhibited steady-state stress produced by KCl (IC50 = 3.7-4.4 microM) and phenylephrine (PhE) (IC50 = 10.6-15.2 microM). Likewise, increases in the level of Mp and the rate of crossbridge cycling induced by both KCl and PhE were significantly reduced by 10 microM H-7. H-7 did not reduce inositol phosphate production stimulated by PhE, but did reduce early stress development thought to be mediated by inositol phosphate-induced mobilization of intracellular calcium. Calcium-induced increases in stress and Mp produced in saponin-skinned artery strips were reduced by less than 50% by 320 microM H-7.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of the kinase inhibitor, H-7, on stress, crossbridge phosphorylation, muscle shortening and inositol phosphate production in rabbit arteries. 229 93


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