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)

The 93 kDa protein gephyrin is a tubulin binding peripheral membrane protein that is associated with the inhibitory glycine receptor and has been implicated in its anchoring at central synapses. Here, we demonstrate that gephyrin as well as co-purifying tubulin are phosphorylated by a kinase activity which is endogenous to highly purified glycine receptor preparations. This kinase phosphorylates serine and threonine residues and utilizes ATP, but not GTP, as phosphate donor. Its activity is not affected by various activators and/or inhibitors of cyclic nucleotide-dependent kinases, calcium/calmodulin-dependent kinases, or protein kinase C. A five-fold stimulation of kinase activity was, however, observed in the presence of poly-lysine. Phosphorylation of gephyrin and/or tubulin might regulate receptor/cytoskeleton interactions at postsynaptic membrane specializations.
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PMID:The 93 kDa protein gephyrin and tubulin associated with the inhibitory glycine receptor are phosphorylated by an endogenous protein kinase. 131 18

Bovine lung cGMP-binding cGMP-specific phosphodiesterase (cG-BPDE) is a potent and relatively specific substrate for cGMP-dependent protein kinase (cGK) as compared to cAMP-dependent protein kinase (cAK) (Thomas, M. K., Francis, S. H., and Corbin, J. D. (1990) J. Biol. Chem. 265, 14971-14978). A synthetic peptide, RKISASEFDRPLR (BPDEtide), was synthesized corresponding to the sequence surrounding the phosphorylation site in cG-BPDE. BPDEtide retained the cGK/cAK kinase specificity demonstrated by native cG-BPDE: the apparent Km of BPDEtide for cGK was 5-fold lower than that for cAK (Km = 68 and 320 microM, respectively). Vmax values were 11 mumol/min/mg for cGK and 3.2 mumol/min/mg for cAK. The peptide was not phosphorylated to a measurable extent by protein kinase C or by calcium/calmodulin-dependent protein kinase II. Thus, the primary amino acid sequence of the peptide substrate was sufficient to confer kinase specificity. Studies in crude tissue extracts indicated that BPDEtide was the most selective peptide substrate documented for measuring cGK activity. Peptide analogs of BPDEtide were synthesized to determine the contribution of specific residues to cGK or cAK substrate specificity. Substitution of a Lys for the amino-terminal Arg did not reduce cGK/cAK specificity; neither did the exchange of an Ala for the non-phosphorylated Ser nor the removal of the 3 carboxyl-terminal residues. A truncated BPDEtide (RKISASE) served equally well as substrate (Km approximately 90 microM) for both kinases. However, restoration of the Phe, to yield RKISASEF, reproduced the original cGK/cAK specificity for BPDEtide (Km = 120 and 480 microM, respectively), primarily by decreasing the affinity of cAK. Addition of a carboxyl-terminal Phe to the peptide RKRSRAE (derived from the sequence of the cGK phosphorylation site in histone H2B) or to the peptide LRRASLG (derived from the sequence of the cAK phosphorylation site in pyruvate kinase) also improved the cGK/cAK specificity by decreasing the affinity of cAK. These data suggested that the Phe in each substrate tested is a negative determinant for cAK.
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PMID:A phenylalanine in peptide substrates provides for selectivity between cGMP- and cAMP-dependent protein kinases. 131 60

The present study involves the effects on corticotropin (ACTH) release of neuro- and thymoleptic tricyclic antidepressant compounds (TrcACs: chlorpromazine, promethazine, haloperidol, imipramine, amitriptyline) and their interactions with lysine-8-vasopressin (LVP) and corticosterone (B). As an in vitro model, 14-day monolayer pituitary cell cultures of Wistar rats were employed. The ACTH concentrations of the supernatant media were measured by radioimmunoassay. TrcACs augmented ACTH release; their combination with LVP, however, did not result in further stimulation; moreover, when combined with TrcACs + LVP, B did not inhibit, but rather paradoxically increased their ACTH-releasing action. As none of these phenomena were followed by relevant changes in intracellular cyclic adenosine monophosphate content, the mechanism of action may be proposed to involve a protein kinase C route.
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PMID:Central effects of tricyclic compounds on the endocrine system--an in vitro study. 132 50

Both keratohyalin granules (KHG) and cornified envelopes were stained histochemically in an indirect immunofluorescent study by antiphosphorylated cystatin alpha antibody, indicating that phosphorylated cystatin alpha is a component of the cornified envelope proteins. When phosphorylated cystatin alpha (P-cystatin alpha) was incubated with epidermal transglutaminase (TGase) and Ca2+ ions, polymerized protein was produced by formation of epsilon-(gamma-glutamyl)lysine cross-linking peptide bonds between lysine residues of cystatin alpha and glutamine residues of suitable protein(s) in the enzyme preparation. However, phosphorylated and non-phosphorylated cystatins were polymerized to similar extents by the TGase. Immunofluorescent and immunoelectron microscopic observations revealed that P-cystatin alpha could be detected in vivo in the KHG and cornified envelopes. Treatment of sphingosine, a specific inhibitor of protein kinase C, markedly suppressed the incorporation of cystatin alpha into KHG. Thus phosphorylation of cystatin alpha by protein kinase C may play an important role in targeting cystatin alpha into KHG.
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PMID:Phosphorylated cystatin alpha is a natural substrate of epidermal transglutaminase for formation of skin cornified envelope. 135 32

Transglutaminase 1 (TG1) is an enzyme that is expressed at the late stage of terminal differentiation of keratinocytes and catalyzes the epsilon-(gamma-glutamyl)lysine cross-linking reaction to form a highly insoluble cell envelope. To elucidate the mechanism of TG1 gene expression in keratinocytes, we examined the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA), dexamethasone, 1,25-dihydroxyvitamin D3, and retinoic acid on the levels of TG1 mRNA in cultured normal human epidermal keratinocytes (NHEK). Treatment of NHEK with TPA, up to 10 nM, markedly increased the levels of TG1 mRNA in a dose-dependent manner. The effect by treatment with 1 nM TPA reached a peak after 16 h of incubation (20-fold above the basal level). In contrast, phorbol had no effect on TG1 gene expression. The induction of TG1 mRNA expression by TPA was inhibited by 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7) and staurosporine. Dexamethasone at a concentration of 1 microM also increased the TG1 mRNA levels, but the maximum induction was observed (3-fold above the basal level) after 72 h of incubation. The effect of dexamethasone was not suppressed by H-7. Moreover, 1 microM of retinoic acid completely inhibited the induction of TG1 mRNA by both TPA and dexamethasone. 1,25-Dihydroxyvitamin D3 showed no effect on the TG1 mRNA levels. From these results, we suggest that the expression of TG1 gene may be upregulated by protein kinase C and glucocorticoid receptor systems and down-regulated by the retinoic acid receptor system.
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PMID:Regulation of transglutaminase 1 gene expression by 12-O-tetradecanoylphorbol-13-acetate, dexamethasone, and retinoic acid in cultured human keratinocytes. 135 18

We investigated the possible role of tyrosine phosphorylation in the activation process of mast cells by cross-linking of cell-bound IgE antibodies. Bone marrow-derived mouse mast cells (BMMC) were sensitized with mouse IgE antiDNP mAb and then challenged with multivalent Ag DNP conjugates of human serum albumin. Analysis of phosphotyrosine-containing proteins in their lysates by SDS-PAGE and immunoblotting revealed that cross-linking of cell-bound IgE antibodies induced a marked increase in tyrosine phosphorylation of several proteins. To obtain direct evidence for activation of protein-tyrosine kinases (PTK), phosphotyrosine-containing proteins in lysates of mast cells were affinity purified, and kinase activity of the immunoprecipitates was assessed by an in vitro kinase assay. The results clearly showed activation of PTK upon cross-linking of Fc epsilon RI. Activation of PTK was not detected by the same assay when the sensitized BMMC were challenged with monovalent DNP-lysine. Treatment of sensitized BMMC with either Ca2+ ionophore or PMA failed to induce the activation of PTK. A representative IgE-independent secretagogue, thrombin, induced histamine release from BMMC but failed to induce activation of PTK. The results excluded the possibility that PTK activation is the consequence of an increase in intracellular Ca2+ or activation of protein kinase C. Addition of genistein, a PTK inhibitor, to sensitized BMMC before Ag challenge inhibited not only Ag-induced PTK activation, but also inositol 1,4,5-trisphosphate production, and histamine release in a similar dose-response relationship. Other PTK inhibitors, such as lavendustin A and tyrphostin RG50864, also inhibited the Ag-induced activation of PTK and histamine release. The results collectively suggest that activation of PTK is an early event upstream of the activation of phospholipase C, and is involved in transduction of IgE-dependent triggering signals to mediator release.
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PMID:Tyrosine phosphorylation is required for mast cell activation by Fc epsilon RI cross-linking. 137 48

A set of peptides derived from myelin basic protein was synthesized and the kinetics of their phosphorylation by protein kinase C was studied. The replacement or the removal of the N-terminal Gln had no effect on the activity of the parent peptide. The removal of the following Lys or Arg led to a systematic decrease in substrate activity. The modifications in the C-terminal part of the peptide had a weaker influence on the parameters Vmax and KM than those in the N-terminal. The rather regular dependence of the activity of substrates upon their structure does not allow the strict definition of a minimum substrate for protein kinase C.
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PMID:Peptide fragments of myelin basic protein as substrates of protein kinase C. 138 95

Two calcium-dependent phospholipid- and membrane-binding proteins have been purified from bovine brain. These are termed CaBP33 and CaBP37. Complete sequence analysis has revealed that these two proteins are isoforms of annexin V. Despite an apparent difference of 4 kDa between the two proteins on SDS-PAGE, only two amino-acid substitutions were found. These are, in CaBP33, Ser-36 and Lys-125 and in CaBP37, Thr-36 and Glu-125. This corresponds to a mass difference of 15 Da. This was confirmed by electrospray mass spectrometric analysis. Both isoforms can be phosphorylated substoichiometrically in vitro by protein kinase C at residue Thr-22.
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PMID:Novel isoforms of CaBP 33/37 (annexin V) from mammalian brain: structural and phosphorylation differences that suggest distinct biological roles. 142 Mar 35

A cytosolic insulin-sensitive serine kinase has been purified to apparent homogeneity in parallel from livers of control or acutely insulin-treated rats. The kinase is labile and requires rapid purification for stability. The kinase migrates as a band of apparent Mr = 90,000 on denaturing gels and elutes as a monomer on Superose 12 gel filtration. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis and renaturation, the 90-kDa band presumed to be the kinase shows kinase activity toward myelin basic protein in situ. Substrates of the kinase include Leu-Arg-Arg-Ala-Ser-Leu-Gly (Kemptide), ribosomal protein S6, S6 peptide, a proline-rich peptide substrate, microtubule-associated protein 2, and myelin basic protein. The kinase also phosphorylates histones H1 and H2B, but does not autophosphorylate to a significant stoichiometry. The activity of the kinase is inhibited by fluoride, glycerophosphate, p-nitrophenyl phosphate, p-nitrophenol, heparin, quercetin, poly-L-lysine, and potassium phosphate, but is unaffected by calcium, cAMP, spermine, protein kinase inhibitor peptide, phorbol myristate acetate, calcium plus phosphatidylserine, or vanadate. The kinase will utilize magnesium (10 mM) as well as manganese (1 mM) as a cofactor for maximal phosphotransferase activity. The kinase is not detected by immunoblotting with antibodies directed against protein kinase C or type II S6 kinase. Taken together, these properties distinguish this kinase from other insulin-sensitive kinases that have been described previously. The purified kinase from livers of insulin-treated rats shows a 5-20-fold higher specific activity compared to enzyme prepared from control rats, suggesting a covalent modification as the mechanism of activation. Incubation of purified, insulin-stimulated kinase with purified phosphatase 2A leads to deactivation of the kinase activity, and the phosphatase inhibitor nitrophenyl phosphate blocks this deactivation. The insulin-activated kinase fails to immunoblot with anti-tyrosine phosphate antibodies. Taken together, these results indicate that insulin activates this novel cytosolic protein kinase by a mechanism that causes its phosphorylation on serine or threonine residues.
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PMID:Purification and characterization of a cytosolic insulin-stimulated serine kinase from rat liver. 153 38

Bacteroides spp. may contribute to the chronicity of mixed infections by affecting the normal functions of polymorphonuclear leukocytes (PMN). This study evaluated the physiologic and biochemical responses of human peripheral blood PMN to a variety of strains of the oral periodontal pathogen Porphyromonas (Bacteroides) gingivalis. Strain 381 and ATCC type strain 33277 caused rapid and lasting depolarization of the electrochemical potential that exists across the PMN membrane by a mechanism that was independent of activation of the pertussis toxin-sensitive G protein or protein kinase C. Membrane depolarization did not initiate increases in intracellular calcium or respiratory burst activation, and activity was not inhibited by surface proteolysis or sugars. However, membrane depolarization was associated with inhibition of PMN responses to the chemotactic peptide N-formylmethionyl leucyl phenylalanine. Membrane-depolarizing activity was isolated with the outer membrane of strain 381 by surface extraction of the bacteria by using Zwittergent 3,14, followed by Sephacryl S-200 gel filtration chromatography. The partially purified outer membrane components were heat stable, were not inhibited by tosyl-lysine chloromethyl ketone, and inhibited N-formylmethionyl leucyl phenylalanine-stimulated superoxide production. The results suggest that outer membrane components of P. gingivalis 381 and 33277 have porinlike activity that can depolarize PMN membranes and immobilize PMN responses to chemotactic peptides. This may prove to be an important virulence characteristic of these strains.
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PMID:Depolarization of polymorphonuclear leukocytes by Porphyromonas (Bacteroides) gingivalis 381 in the absence of respiratory burst activation. 165 60


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