Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of PC12h cells with nerve growth factor (NGF) induced a transient increase in the phosphorylation of a 35,000-dalton protein. This transient increase was observed also when extracts of NGF-treated cells were incubated with [gamma-32P]ATP. In the intact-cell phosphorylation system, treatment with N,2'-dibutyryladenosine 3',5'-cyclic monophosphate (dBcAMP) or 12-O-tetradecanoylphorbol 13-acetate (TPA) also induced a transient increase in the phosphorylation of the 35,000-dalton protein, but the effect was less than that of NGF. An effect comparable to that of NGF was obtained by the combination of dBcAMP and TPA. Pretreatment of PC12h cells with dBcAMP plus TPA for 3 days, which deprived the cells of their ability to respond to a rechallenge with dBcAMP, TPA, or dBcAMP plus TPA by increasing the rate of 35,000-dalton protein phosphorylation, caused only a slight attenuation of the NGF effect, directly indicating a minimal role of cyclic AMP (cAMP)-dependent protein kinase and protein kinase C in the mechanism of the NGF action. Pretreatment of the cells with K-252a, a protein kinase inhibitor, at a concentration of 300 nM almost completely blocked the action of NGF, but scarcely affected the action of dBcAMP, TPA, or dBcAMP plus TPA in intact-cell phosphorylation experiments. This NGF-sensitive 35,000-dalton protein was a ribosomal protein and identified as ribosomal protein S6. The results lead us to conclude that NGF activates some NGF-sensitive component(s), probably some specific protein kinase(s) other than cAMP-dependent protein kinase or protein kinase C, which is suppressed by K-252a and directly or indirectly activates a 35,000-dalton protein kinase(s) [S6 kinase(s)] to increase the rate of phosphorylation of the 35,000-dalton ribosomal protein (S6).
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PMID:Nerve growth factor-induced transient increase in the phosphorylation of ribosomal protein S6 mediated through a mechanism independent of cyclic AMP-dependent protein kinase and protein kinase C. 216 78

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

Two characteristic responses of plant cells to fungal elicitors, induction of phenylalanine ammonia-lyase activity and of ethylene biosynthesis, were studied in suspension-cultured tomato cells. Induction of both responses was completely blocked by 500 nM K-252a, a known inhibitor of mammalian protein kinases. About 100 nM K-252a caused half-maximal inhibition. In vitro, K-252a inhibited protein kinase activity in microsomal preparations from tomato cells. Inhibition was competitive with respect to ATP and had a Ki of about 15 nM. Thus, protein kinases sensitive to K-252a occur in plants and might be important for the plant's response to fungal elicitors.
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PMID:K-252a inhibits the response of tomato cells to fungal elicitors in vivo and their microsomal protein kinase in vitro. 226 87

The rise of the NGF mRNA pool which takes place following exposure of L-929 fibroblasts to serum was prevented in the presence of 5 microM K-252a, a compound which inhibits several species of protein kinase activities. To characterize further this phenomenon, L-929 cells growing in a serum-free medium were exposed to cyclic nucleotide analogs, to a divalent cation ionophore or to the phorbol ester PMA. Only this latter compound induced an enhancement of the NGF mRNA pool, suggesting an involvement of protein kinase C in the upregulation of the NGF transcripts. The effects of PMA or serum also require a synthesis of protein since the level of NGF transcripts remained stable in the presence of cycloheximide.
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PMID:Phorbol 12-myristate 13-acetate (PMA) increases the expression of the nerve growth factor (NGF) gene in mouse L-929 fibroblasts. 231 11

KT5926, (8R*,9S*,11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-14-n-propoxy-2,3 ,9, 10-tetrahydro-8,11-epoxy, 1H,8H, 11H-2,7b,11a-triazadibenzo[a,g]cycloocta[cde] trinden-1-one, was found to be a potent and selective inhibitor of myosin light chain kinase. The compound inhibited both Ca2+/calmodulin-dependent and -independent smooth muscle myosin light chain kinases to a similar extent. The inhibition was not affected by the concentration of calmodulin. Kinetic analyses showed that the mode of inhibition was of the competitive type with respect to ATP (Ki, 18 nM) and of the noncompetitive type with respect to myosin light chain (Ki, 12 nM). These results indicated that KT5926 directly interacted with the enzyme at the catalytic site. KT5926 also inhibited other protein kinases, but with relatively high Ki values; the values for protein kinase C, cAMP-dependent protein kinase, and cGMP-dependent protein kinase were 723, 1200, and 158 nM, respectively. Ca2(+)-ATPase, Na+/K(+)-ATPase, hexokinase, and 5'-nucleotidase were not inhibited by KT5926 at less than 10 microM. The effect of KT5926 on serotonin secretion and protein phosphorylation induced by platelet-activating factor or phorbol ester was examined in rabbit platelets. KT5926 inhibited the phosphorylation of a 20-kDa protein but had no effect on the phosphorylation of a 40-kDa protein, thereby indicating that the compound exerts its selective inhibition of myosin light chain kinase in intact cells. The compound inhibited serotonin secretion induced by platelet-activating factor, but its potency was significantly less than that of K-252a, (8R*,9S*,11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9, 10-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b, 11a-triazadibenzo[a,g]cycloocta [cde]trinden-1-one, which inhibited the phosphorylation of both the 20-kDa protein and the 40-kDa protein. Phorbol ester-induced secretion was not suppressed by KT5926. These results provide the evidence that both the 20-kDa protein phosphorylation by myosin light chain kinase and the 40-kDa protein phosphorylation by protein kinase C substantially contribute to the secretion response in platelets.
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PMID:KT5926, a potent and selective inhibitor of myosin light chain kinase. 232 35

The microbial alkaloid staurosporine is a member of a recently described family of protein kinase inhibitors. [N,N-dimethyl-3H]N-dimethylstaurosporine ([3H]DMS) was prepared from staurosporine by methylation with [3H]methyl iodide. Since staurosporine inhibits protein kinase C (PKC) most potently, the binding of [3H]DMS to this enzyme was examined. Unlike [20-3H(N)]phorbol-12,13-dibutyrate ([3H]PDBu) binding to PKC, [3H]DMS binding was not calcium or phosphatidylserine (PS) dependent. Binding was reversible, with a T1/2 of 69 min and a Koff of 0.01/min. Non-specific binding was defined by a 500-fold molar excess of staurosporine and was less than 10% of total [3H]DMS binding. Specific binding of [3H]DMS was consistent with a single class of binding sites with a Kd of 3.8 +/- 0.6 nM and a Bmax of 675 +/- 30 pmol/g tissue. In competition experiments, staurosporine inhibited [3H]DMS binding with a Ki of 4.7 +/- 0.6 nM, indicating that the two alkaloids had a similar potency for PKC. Also, unlabeled DMS and staurosporine inhibited [3H]DMS binding and PKC catalysis with equivalent potencies. Highly purified rat brain PKC bound equimolar amounts of [3H]PDBu and [3H]DMS. In contrast, crude rat brain PKC, which had been proteolysed to generate a PS and Ca2+ independent enzyme (PK-M) retained the ability to bind [3H]DMS, but not [3H]PDBu. In addition, the kinase inhibitors K-252a and H-7 [1-(5-isoquinolinesulfonyl)-2-methylpiperazine] inhibited [3H]DMS binding, whereas PDBu did not. These results indicate that [3H]DMS is a useful ligand to identify catalytic inhibitors of kinase activity and to explore their mechanisms of action.
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PMID:Characterization of specific [3H]dimethylstaurosporine binding to protein kinase C. 237 70

Possible involvement of protein kinases in the serotonin (5-HT) transport system in platelets and the inhibitory effect of concanavalin A (Con A) on platelet 5-HT uptake were investigated. Staurosporine and K-252a, highly active inhibitors of protein kinases, did not inhibit 5-HT transport, but they antagonized the inhibitory effect of Con A on 5-HT uptake. KT5720, a protein kinase A inhibitor that has no effect on protein kinase C, neither affected 5-HT transport nor antagonized the inhibitory effect of Con A on 5-HT uptake. The Con A effect on 5-HT uptake was also antagonized by LaCl3, a Ca++ entry blocker. When the activity of Ca++ transport into platelets was estimated, Con A was shown to have a stimulative effect, which was antagonized by alpha-methyl-D-mannoside, a specific antagonist of Con A binding to cell membrane glycoproteins. Furthermore, Con A was shown to stimulate the protein kinase C activity of platelets, which phosphorylates a 40-kDa platelet protein; the Con A effects were antagonized by alpha-methyl-D-mannoside, staurosporine and K-252a, but not by KT5720. We suggest that the activation of protein kinase C and phosphorylation of 40-kDa protein might be involved in the inhibitory effect of Con A on platelet 5-HT transport.
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PMID:Effect of concanavalin A on serotonin transport into blood platelets: possible involvement of protein kinase C. 239 68

Binding of [3H]-staurosporine to different protein kinases was time-dependent, reversible and saturable. Scatchard analysis of saturation isotherms indicated one class of binding sites for [3H]-staurosporine with dissociation constants (KD) of 9.6, 2.0, 3.0 and 7.4 nM for protein kinase C, cAMP-dependent protein kinase, tyrosine protein kinase and calcium/calmodulin-dependent protein kinase respectively. [3H]-staurosporine binding was fully displaced by unlabelled staurosporine or the related compound K-252a whereas other protein kinase inhibitors (H-7, H-8 and W-7) did not compete with [3H]-staurosporine. These data confirm that sataurosporine shows no selectivity for different protein kinases and suggest the putative existence of distinct, specific binding sites for [3H]-staurosporine on these enzymes.
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PMID:Characterization of specific binding sites for [3H]-staurosporine on various protein kinases. 239 90

In this study, we investigated the role of calcium and phospholipid-dependent protein kinase (protein kinase C, PKC) in the modulation of histamine release from human basophils. A novel and potent inhibitor of PKC, K-252a, inhibited the release of histamine induced by anti-IgE in a dose-dependent manner with ID50 (the dose required for 50% inhibition of histamine release) of 2.2 x 10(-8) M. Histamine release stimulated with 12-0-tetradecanoyl-phorbol-13-acetate(TPA) was also suppressed by K-252a with maximal inhibition of 48.0 +/- 9.3% at 10(-7) M. In contrast, K-252a did not inhibit the release of histamine in response to FMLP and ionophore A23187. Another inhibitor of PKC, H-7, exhibited a dose-dependent inhibition of anti-IgE-induced histamine release with ID50 of 8.6 x 10(-4) M. H-8 and HA1004, which closely resemble H-7 in chemical structure but are less potent in inhibiting PKC, did not inhibit histamine release stimulated with anti-IgE, but rather enhanced the release at higher concentrations. These results strongly suggest that PKC activation plays a crucial role in the mediation of IgE-mediated histamine release from human basophils.
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PMID:Role of protein kinase C in histamine release from human basophils. 245 80

Previously, we have shown that okadaic acid (OA), isolated from black sponge (Halichondria okadai) causes contraction even in the absence of Ca++ in the saponin-permealized taenia isolated from guinea pig cecum. In the present study, mechanism of action of OA was examined using native actomyosin extracted from chicken gizzard smooth muscle. In the absence of Ca++, OA (0.1-1 microM) induced superprecipitation and increased the Mg++-adenosine triphosphatase activity. The OA-induced superprecipitation was enhanced by Ca++ at a concentration (greater than 0.1 microM) which did not activate the calmodulin-dependent myosin light chain (MLC) kinase. The effect of OA was not affected by the calmodulin inhibitor, trifluoperazine, at a concentration (100 microM) needed to inhibit the Ca++-induced response, but was inhibited markedly by the nonselective kinase inhibitors, amiloride (1 mM) and K-252a (5 microM). The OA-induced superprecipitation in the absence of Ca++ was accompanied by phosphorylation of the 20 K dalton MLC, which also was enhanced by low concentration of Ca++ (greater than 0.1 microM). OA did not change the phosphatase activity which dephosphorylates the phosphorylated MLC. An activator of Ca++- and phospholipid-dependent protein kinase, 12-O-tetradecanoylphorbol 13-acetate (1 microM), did not modulate superprecipitation or phosphorylation of MLC in the presence and absence of OA. Furthermore, inhibitors of Ca++ and phospholipid-dependent protein kinase, 1-(5-isoquinoline-sulfonyl)-2-methylpiperazine dihydrochloride (400 microM) and polymyxin B (100 micrograms/ml), affected neither superprecipitation nor phosphorylation of MLC induced by OA. With a reconstituted system containing purified myosin and MLC kinase, OA induced only slight phosphorylation of MLC.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcium-independent phosphorylation of smooth muscle myosin light chain by okadaic acid isolated from black sponge (Halichondria okadai). 282 58


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