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)

The activities of rat brain protein kinase C isoenzymic fractions separated by hydroxyapatite chromatography were measured with histone H1 or the oligopeptide Ala-Ala-Ala-Ser-Phe-Lys-Ala-Lys-Lys-amide as substrates. The oligopeptide was a better substrate than histone H1 for nearly all of the protein kinase C fractions. Two subfractions of type III isoenzyme were resolved (IIIa and IIIb); type IIIb was characterized by a very low histone kinase activity compared to its peptide kinase activity. In some brain extracts a phospholipid-dependent but Ca2+-inhibited protein kinase was also observed which was eluted from the hydroxyapatite column between type II and III isoenzymes of protein kinase C.
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PMID:Two components of type III protein kinase C with different substrate specificities and a phospholipid-dependent but Ca2+-inhibited protein kinase in rat brain. 254 54

We have evaluated the possibility that a major, abundant cellular substrate for protein kinase C might be a calmodulin-binding protein. We have recently labeled this protein, which migrates on sodium dodecyl sulfate-gel electrophoresis with an apparent Mr of 60,000 from chicken and 80,000-87,000 from bovine cells and tissues, the myristoylated alanine-rich C kinase substrate (MARCKS). The MARCKS proteins from both species could be cross-linked to 125I-calmodulin in a Ca2+-dependent manner. Phosphorylation of either protein by protein kinase C prevented 125I-calmodulin binding and cross-linking, suggesting that the calmodulin-binding domain might be located at or near the sites of protein kinase C phosphorylation. Both bovine and chicken MARCKS proteins contain an identical 25-amino acid domain that contains all 4 of the serine residues phosphorylated by protein kinase C in vitro. In addition, this domain is similar in sequence and structure to previously described calmodulin-binding domains. A synthetic peptide corresponding to this domain inhibited calmodulin binding to the MARCKS protein and also could be cross-linked to 125I-calmodulin in a calcium-dependent manner. In addition, protein kinase C-dependent phosphorylation of the synthetic peptide inhibited its binding and cross-linking to 125I-calmodulin. The peptide bound to fluorescently labeled 5-dimethylaminonaphthalene-1-sulfonyl-calmodulin with a dissociation constant of 2.8 nM, and inhibited the calmodulin-dependent activation of cyclic nucleotide phosphodiesterase with an IC50 of 4.8 nM. Thus, the peptide mimics the calmodulin-binding properties of the MARCKS protein and probably represents its calmodulin-binding domain. Phosphorylation of these abundant, high affinity calmodulin-binding proteins by protein kinase C in intact cells could cause displacement of bound calmodulin, perhaps leading to activation of Ca2+-calmodulin-dependent processes.
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PMID:Phosphorylation-regulated calmodulin binding to a prominent cellular substrate for protein kinase C. 255 40

Spinal cord slice preparation and intracellular recording techniques were used to examine the effects of phorbol esters on the sodium- and calcium-dependent action potentials, the excitatory synaptic transmission, the basal (resting) and the dorsal root stimulation-evoked release of 9 endogenous amino acids, including glutamate and aspartate, and the responsiveness of the rat dorsal horn neurons to excitatory amino acids (glutamic, kainic, quisqualic, and N-methyl-D-aspartic). 4-beta-Phorbol-12, 13-dibutyrate and 4-beta-phorbol-12, 13-diacetate produced minor alterations in membrane potential and resistance, but they broadened the sodium-dependent action potential and reduced the duration of the calcium-dependent action potential. In addition, phorbol esters caused a marked and long-lasting increase in the amplitude and the duration of excitatory postsynaptic potentials (EPSPs) evoked in dorsal horn neurons by orthodromic stimulation of a lumbar dorsal root. Phorbol esters produced a brief increase in the basal and electrically evoked release of endogenous excitatory (glutamic, aspartic) and inhibitory amino acids (glycine, GABA). In addition, the rates of release of alanine, serine, and threonine were also elevated. In the presence of TTX, phorbol esters selectively enhanced, in a reversible manner, the depolarizing responses of dorsal horn neurons to N-methyl-D-aspartic acid and L-glutamate but not the responses to kainic or quisqualic acids. The potentiation of the NMDA response was blocked by APV, a specific NMDA receptor antagonist. Thus, phorbol esters appear to enhance excitatory synaptic transmission in the rat spinal dorsal horn slice preparation by acting both at pre- and postsynaptic sites. Phorbol esters could potentiate excitatory synaptic transmission by acting predominantly at a postsynaptic site (NMDA receptor), since the duration of the increased responsiveness of dorsal horn neurons to glutamate and NMDA correlates better with the enhancement of EPSPs than with the increased release of the stimulation-evoked glutamate and aspartate. The increased release of endogenous amino acids is consistent with a presynaptic (terminal) site of action, but it could also be explained by enhanced interneuronal activity. Although our results suggest that in the rat spinal dorsal horn protein kinase C may have a role in controlling the release of putative excitatory and inhibitory neurotransmitters and may also be involved in the regulation of postsynaptic NMDA receptors, the identity of endogenous substance(s) participating in these effects is presently unknown.
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PMID:Multiple effects of phorbol esters in the rat spinal dorsal horn. 257 84

Little is known about the important cellular substrates for protein kinase C (PKC) and their function in the cellular processes influenced by this kinase. This paper describes the molecular characteristics of a prominent cellular substrate for PKC in chicken cells, known as the myristoylated alanine-rich C kinase substrate, or MARCKS protein. The chicken protein was studied because it was apparently at least 20 kilodalton smaller than its mammalian counterpart; we hoped that regions of sequence similarity might point to conserved regions of biological importance. Using the bovine MARCKS cDNA as a probe, we selected a positive clone from a chicken brain cDNA library that contained an insert of about 1.5 kilobase, in which a single open reading frame encoded a protein of 281 amino acids, 27.7 kilodaltons, pI 5.26. This protein contained the sequences of ten tryptic peptides derived from the purified chicken brain protein. Expression of the cDNA insert in mammalian cells confirmed that the open reading frame encoded a protein that comigrated on two-dimensional electrophoresis with the authentic chicken protein, and could be phosphorylated by exposure of the cells to active phorbol esters. When the chicken and bovine protein sequences were compared, the two major regions of sequence identity were: 1) the amino terminal region containing a myristoylation consensus sequence and an mRNA splice site, and 2) a highly basic internal domain of 25 amino acids that contained all of the serines known to be phosphorylated by PKC in the intact protein. These conserved regions are likely to represent domains of some functional importance for this widely distributed cellular substrate for PKC.
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PMID:Molecular cloning, sequence, and expression of a cDNA encoding the chicken myristoylated alanine-rich C kinase substrate (MARCKS). 260 63

We isolated and sequenced a cDNA clone encoding the bovine "80- to 87-kDa" protein, a major cellular substrate for protein kinase C. An open reading frame of 1005 base pairs predicted a protein of 335 amino acids (Mr, 31,949). Despite this predicted size, the protein migrated on SDS/polyacrylamide gels with an apparent molecular weight of 80-87,000 after expression of the cDNA in cells lacking the protein. It was highly enriched in alanine (28.4 mol %), contained an amino-terminal myristoylation consensus sequence, and included a 25-residue basic domain containing the known protein kinase C phosphorylation sites. Two mRNA species (2.6 and 4.4 kilobases) were most highly expressed in brain, spinal cord, spleen, and lung, in parallel with the distribution of immuno-reactive protein. Genomic blot analysis indicated the likelihood of a single gene coding for this mRNA. We propose the name myristoylated alanine-rich C kinase substrate (MARCKS) for this protein.
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PMID:Molecular cloning, characterization, and expression of a cDNA encoding the "80- to 87-kDa" myristoylated alanine-rich C kinase substrate: a major cellular substrate for protein kinase C. 272 63

A 29-residue synthetic peptide, Leu530-Leu-Tyr-Glu-Met-Leu-Ala-Gly-Gln-Ala-Pro-Phe-Glu-Gly-Glu-Asp -Glu-Asp- Glu-Leu-Phe-Gln-Ser-Ile-Met-Glu-His-Asn-Val-NH2(558), corresponding to part of the catalytic domain of protein kinase C, is a potent activator of the enzyme, with a Ka of approx. 10 microM. Activation was 59 +/- 4% of that observed with phosphatidylserine, predominantly due to an increased Vmax, partially calcium-dependent, observed with all three isoenzymes (alpha, beta, gamma), and resulted in autophosphorylation. It is proposed that the region between Gly528 and Arg583 is part of the protein substrate binding region of protein kinase C and synthetic peptide analogs of this region activate the enzyme by blocking the action of the enzyme's basic pseudosubstrate autoregulatory region.
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PMID:A synthetic peptide analog of the putative substrate-binding motif activates protein kinase C. 273 83

The peptide Leu-Asp-Asp-Ser-Lys-Arg-Val-Ala-Lys-Arg-Lys-Leu-Ile-Glu, which corresponds to sequence 124 to 137 of c-erb-A protein, was synthesized and tested as substrate for protein kinase C (PKC). Although a typical recognition sequence for PKC, consisting of a cluster of basic residues, is found on the C-terminus side of serine, its phosphorylation was totally prevented by the presence of the two acidic residues on the amino-terminus side. Three analogs in which aspartyl residues were successively replaced with alanine were studied and the influence of the acidic side chain in modulating phosphorylation by PKC was thus possible to determine. The results show that the presence of a single aspartyl residue located in positions i-1 or i-2 with respect to the phosphorylable residue can almost totally abolish the positive effect of a highly favorable cluster of basic residues. These observations highlight the role of negative substrate specificity determinants in settling the protein substrate profile of protein kinase C.
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PMID:Evidence for negative control in protein kinase C substrate specificity. 275

The intracellular signal pathways that mediate pigmentation in human skin are unknown. We now report that a diacylglycerol (DAG) analogue 1-oleoyl-2-acetyl-glycerol (OAG) 25-100 microns strikingly increased the melanin content of cultured human melanocytes in a dose dependent manner without altering growth rate. The pigment increase occurred within 24 h, was accompanied by increased incorporation of the melanin precursor L-3,4-dihydroxyphenyl alanine (DOPA), required new protein synthesis, and was completely blocked by the protein kinase C (PKC) inhibitors H-7 and sphingosine. A PKC-inactive DAG isomer had no effect on melanin per cell. These results implicate protein kinase C and its effector DAG in melanogenesis.
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PMID:Human melanogenesis is stimulated by diacylglycerol. 215 70

A novel protein kinase which could be inhibited specifically by gangliosides has been partially purified from the particulate fraction of guinea pig brain through extraction with nonionic detergent, ion-exchange chromatography, hydrophobic chromatography, hydroxylapatite chromatography, and gel filtration. The ganglioside-inhibited kinase activity was eluted with a Stokes radius of 29-30 A, corresponding to a globular protein of approximately 40,000 in molecular weight. Only gangliosides, especially polysialogangliosides, are potent inhibitors for this enzyme preparation. The modulatory action of the glycolipids on the kinase activity is not time-dependent, indicating that the mode of inhibition may not be mediated through a ganglioside-dependent proteolytic process. Calcium was not required for the inhibitory effects of the various gangliosides tested, suggesting that prior formation of Ca2+.ganglioside complexes are not necessary. The partially purified ganglioside-inhibited protein kinase can phosphorylate exogenous substrates such as a synthetic peptide Leu-Arg-Arg-Ala-Ser-Leu-Gly. The optimal pH for this reaction occurred between 7.0 and 7.4. Mg2+ (5-10 mM) is required for the enzymic activity and cannot be substituted by Mn2+. Although the nature of the authentic substrates for this ganglioside-inhibited protein kinase is yet unknown, a search for other potential substrates revealed that the synthetic peptide Arg-Arg-Lys-Ala-Ser-Gly-Pro-Pro-Val was the best phosphate acceptor tested so far. Other substrate specificity studies also showed that the ganglioside-inhibited protein kinase is distinct from either the ganglioside-stimulated protein kinase or protein kinase C. Thus, it is possible that gangliosides can act as bio-modulators which may confer a synchronistic action on these three different protein kinase systems.
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PMID:Ganglioside-modulated protein phosphorylation. Partial purification and characterization of a ganglioside-inhibited protein kinase in brain. 282 49

Protein phosphatase T from rat liver, so termed due to its activity toward [32P-Thr]casein and its marked preference for the phosphopeptide Arg-Arg-Ala-Thr(P)-Val-Ala over its phosphoseryl derivative (Donella Deana, A., Marchiori, F., Meggio, F. and Pinna, L.A. (1982) J. Biol. Chem. 257, 8565-8568), is shown here to belong to the family of type 2A protein phosphatase according to Cohen's nomenclature (Ingebritsen, T.S. and Cohen, P. (1983) Eur. J. Biochem. 132, 255-261). In particular, protein phosphatase T is endowed with phosphorylase phosphatase activity that is stimulated by protamine, histone H1 and heparin, it is inhibited by spermine, it does not bind to heparin-Sepharose and it readily dephosphorylates the phosphopeptide Arg-Arg-Leu-Ser(P)-Ile-Ser-Thr-Glu-Ser reproducing the phosphorylation site of the alpha-subunit of phosphorylase kinase. The Mr of protein phosphatase T determined by gel filtration under non-denaturating conditions is about 150 kDa and its activity ratio toward histone H1 phosphorylated by protein kinase C versus histone H1 phosphorylated by cAMP-dependent protein kinase is unusually high. Some properties of protein phosphatase T, such as its weak binding to DEAE-cellulose and its high stimulation by protamine as compared to a relatively poor stimulation by histone H1, suggest that it may be similar to subtype 2Ao of protein phosphatase 2A.
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PMID:Identification of pseudo 'phosphothreonyl-specific' protein phosphatase T with a fraction of polycation-stimulated protein phosphatase 2A. 282 78


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