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)

Cys-cdc2(8-20), a synthetic peptide derived from p34cdc2, was previously reported to be a specific and efficient substrate of a pp60c-src-related tyrosine kinase isolated from bovine spleen (the spleen tyrosine kinase) (Litwin, C.M.E., Cheng, H.-C., and Wang, J.H. (1991) J. Biol. Chem. 266, 2557-2566). The longer peptide, cdc2(1-24), was found to be phosphorylated by the kinase with similar efficiency, and Tyr15 was the only amino acid residue phosphorylated. This indicated that the amino acid sequence of cdc2(8-20) peptide, EKI-GEGTYGVVYK, contained the structural features important for protein tyrosine kinase substrate activity. A stepwise procedure using synthetic peptides was employed to investigate such structural features. First, a computer search of protein sequences homologous to cdc2(8-20) uncovered five protein kinases containing homologous sequence with tyrosine at a position corresponding to Tyr15 of p34cdc2. Second, a peptide derived from ribosomal S6 protein kinase (rsk(436-456] was synthesized. The rsk(436-456) peptide contained a segment, ETIGVGSYSVCKR, which is highly homologous to that of cdc2(8-20). It was found to be a very poor substrate of the spleen tyrosine kinase. Third, peptide analogs of cdc2(6-20) with single substitutions of amino acid residues Lys9, Glu12, Thr14, Gly16, Val18, and Tyr19 by amino acid residues at corresponding positions of rsk were synthesized and tested as spleen tyrosine kinase substrates. Only Glu12 and Thr14 substituted peptide analogs showed decreased substrate activities. (The substrate activity of a peptide is the ability of the peptide to serve as the substrate of the spleen tyrosine kinase. It was determined of the spleen tyrosine kinase. It was determined either by the kinetic parameters (Km and Vmax) of phosphorylation of the peptide or by the initial phosphorylation rate of the peptide by the spleen tyrosine kinase.) An analog with double substitution at Glu12 An analog with double substitution at Glu12 and Thr14 was found to be almost as poor a substrate as the rsk peptide. In addition, peptide analogs with Tyr15 substituted by Phe or D-Tyr had poor substrate activities as well as weak inhibitory activities. Thus, Glu12, Thr14, and Tyr15 residues of p34cdc2 contained structural components essential for the efficient phosphorylation of the peptides derived from p34cdc2 by the pp60c-src-related spleen tyrosine kinase.
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PMID:Structural basis of specific and efficient phosphorylation of peptides derived from p34cdc2 by a pp60src-related protein tyrosine kinase. 171 44

p19 is a highly conserved 19-kDa cytosolic protein that undergoes phosphorylation in mammalian cells upon activation of several distinct signal transduction pathways. Its expression is widespread but developmentally regulated. To determine the in vivo phosphorylation site(s) of p19, the protein was purified from bovine brain and resolved into the unphosphorylated form (p19) and a mixture of the two predominant phospho-forms (pp19). Proteolytic fragments of p19 and pp19 were examined by liquid chromatography/mass spectrometry (LC/MS). We detected ion masses corresponding to fragments spanning the entire amino acid sequence as deduced from the cDNA except for those predicted to contain an unmodified amino terminus. Instead, the digests revealed ions corresponding to peptides lacking the initiator methionine and containing an N-acetylated alanine at the amino terminus. The analysis of pp19, but not that of p19, revealed two sets of ions representing peptides whose m/z values differed by 80 atomic mass units, the incremental mass of a phosphate residue. These putative phosphate-bearing peptides were sensitive to alkaline phosphatase treatment. Using combined trypsin and V8 protease digestions, the phosphorylation sites were mapped to Ser-25 and Ser-38, in the peptides Leu-Ile-Leu-Ser*-Pro-Arg and Phe-Pro-Leu-Ser*-Pro-Pro-Lys, respectively. Interestingly, both phosphoserines are in a very similar sequence context, suggesting that a single proline-directed serine protein kinase, possibly p34cdc2, is responsible for phosphorylation of both sites in vivo.
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PMID:Analysis of phosphoprotein p19 by liquid chromatography/mass spectrometry. Identification of two proline-directed serine phosphorylation sites and a blocked amino terminus. 173 1

The human trk oncogene (originally identified in a colon carcinoma) was activated by a genetic rearrangement which resulted in replacement of the extracellular ligand-binding domain of the proto-trk transmembrane receptor by non-muscle tropomyosin sequences. The product of the trk oncogene, a protein of 70 kDa (p70trk), possesses tyrosine-specific protein kinase activity, is autophosphorylated in vitro on tyrosine and is phosphorylated on serine, threonine and tyrosine residues in trk-transformed cells. By site-directed mutagenesis of trk oncogene cDNA, the codon for lysine (367) at the putative ATP-binding site was changed to that for methionine and the codons for tyrosines (503 and 504) at the putative autophosphorylation sites were changed to those for phenylalanine. Replacement of Lys-367 by methionine results in a biologically inactive, kinase-negative mutant. Phe-ala mutants of trk showed drastically reduced ability to induce morphologic transformation, anchorage-independent growth and tumorigenicity in mouse NIH3T3 cells and showed reduced in vitro tyrosine kinase activity when assayed by autophosphorylation and phosphorylation of histone as exogenous substrate. The present study indicates the role of these specific conserved residues in regulating the biochemical and biological properties of p70trk oncoprotein.
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PMID:Mutational analysis of conserved residues in the tyrosine kinase domain of the human trk oncogene. 183 50

Calcium- and phospholipid-dependent protein kinase (protein kinase C; PKC) may be an important mediator in transduction of some of the cellular actions of insulin. We studied PKC activity in freshly isolated circulating mononuclear cells obtained from healthy subjects and patients with non-insulin-dependent (type II) diabetes mellitus (NIDDM). The kinase activity was measured using a specific nonapeptide substrate, Ala-Ala-Ala-Ser-Phe-Lys-Ala-Lys-Lys-amide. There was negligible calcium- and phospholipid-independent kinase activity in cytosolic and particulate fractions of cells from both control and diabetic subjects. Total (cytosolic and particulate) PKC activity of mononuclear cells from poorly controlled diabetic patients was significantly reduced compared with controls; this reduction was mainly due to a decrease in the cytosolic kinase activity. Tumor-promoting phorbol ester (TPA, 0.1 mumol/L) induced translocation of PKC activity in control cells; in contrast, this subcellular redistribution was not observed in cells from a majority of poorly controlled diabetic subjects. Increased calcium influx into the cells caused by the calcium ionophore A23187-triggered translocation of PKC activity in control cells, while it was ineffective in cells from poorly controlled diabetic patients. Cells from well-controlled diabetic patients demonstrated TPA-induced translocation of the PKC activity approaching that of control cells. The total PKC activity in cells from patients with good glycemic control was normal. Impaired activation of PKC is thus associated with the insulin resistance found in patients with poorly controlled NIDDM.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Impaired translocation of protein kinase C activity in human non-insulin-dependent diabetes mellitus. 186 31

Platelet-activating factor is a potent proinflammatory lipid mediator which directly stimulates neutrophil chemotaxis, degranulation, aggregation, and superoxide radical (O2-) production. PAF also modifies or 'primes' neutrophil responses to other agents. Although a relatively weak direct oxidative agonist, PAF markedly enhances O2- release evoked by phorbol myristate acetate (PMA) and the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), increasing the maximal rate of O2- production by a calcium-dependent mechanism. PAF also increases protein kinase activity in the membrane fraction of neutrophils. In search of a mechanism for oxidative priming by PAF, we investigated the role of PAF in modifying PMA-induced activation/translocation of protein kinase C (PKC) in human neutrophils. In the presence of PAF and PMA both PKC and calcium-, phospholipid-independent protein kinase activities in particulate fractions increase markedly over activities detected in the presence of PMA alone. The increase in particulate protein kinase activities requires the presence of cytochalasin B and is calcium-dependent. The PKC-enhancing effect of PAF may be involved in the mechanism whereby the phospholipid 'primes' neutrophils for augmented oxidative responses to some stimuli but the exact role of PKC in neutrophil oxidative metabolism remains to be defined.
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PMID:Priming of neutrophil oxidative responses by platelet-activating factor. 196 14

The first two steps of de novo pyrimidine synthesis in Saccharomyces cerevisiae are catalyzed by a multifunctional protein, coded by the URA2 gene and which has the carbamoyl-phosphate (CPSase) synthetase and aspartate transcarbamylase (ATCase) activities. The native enzyme purified from protease-B-deficient URA2-transformed cells, was phosphorylated in vitro using catalytic subunits of pure cAMP-dependent protein kinase. After electrophoresis under denaturing conditions, a single 240-kDa species was found to be phosphorylated. Trypsin digestion of this species gave a single, very acidic phosphopeptide upon isoelectric focussing. Purification by HPLC followed by amino acid sequencing of this peptide, showed a phosphoserine at the expected consensus sequence Arg-Arg-Phe-Ser. Knowledge of the URA2 gene sequence allowed the site to be located in the peptide link between dihydroorotase-like and ATCase domains. Such a location may explain why phosphorylation of the URA2 protein changed neither CPSase and ATCase activities nor their sensitivity to UTP, their common specific inhibitor.
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PMID:Yeast carbamoyl-phosphate-synthetase--aspartate-transcarbamylase multidomain protein is phosphorylated in vitro by cAMP-dependent protein kinase. 197 85

A cytoskeletal extract of pure axoplasm, highly enriched with neurofilaments (ANF), was prepared from the giant axon of the squid. This ANF preparation also contained potent kinase activities which phosphorylated the Mr greater than 400,000 (high molecular weight) and Mr 220,000 squid neurofilament protein subunits. High salt (1 M) extraction of this ANF preparation solubilized most of the neurofilament proteins and kinase activities and gel filtration on an AcA 44 column separated these two components. The neurofilaments eluted in the void volume of the column while the kinase activities eluted in the 17-44-kDa range of the column. Two major kinase activities were measured in this peak of activity. One of these strongly phosphorylated the phosphate acceptor peptide Leu-Arg-Arg-Ala-Ser-Leu-Gly (Kemptide) and was completely inhibited by the selective inhibitor of cAMP-dependent kinase Thr-Thr-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-Ile- NH2 (Wiptide). Since addition of cAMP did not stimulate activity, this suggested that this kinase was a free catalytic subunit of cAMP-dependent kinase associated with the neurofilaments. The second kinase activity most effectively phosphorylated alpha-casein, and this activity was not affected by Wiptide. The alpha-casein phosphorylating activity (ANF kinase) was the principal activity responsible for neurofilament protein phosphorylation, and was not inhibited by various inhibitors against second messenger regulated kinases, suggesting it was related to the casein kinase family. Four lines of evidence indicate ANF kinase was similar to casein kinase I. These were: 1) the apparent molecular weight determined by gel filtration and the chromatographic elution profile on phosphocellulose column corresponded to casein kinase I; 2) heparin, an inhibitor of casein kinase II at 2-5 micrograms/ml, stimulated both ANF kinase and purified casein kinase I at these concentrations, while CKI-7, a relatively selective inhibitor of casein kinase I, inhibited ANF kinase in a comparable dose-response fashion; 3) purified casein kinase I strongly phosphorylated both ANF protein subunits (like ANF kinase) whereas casein kinase II was relatively ineffective; and 4) tryptic peptide maps of the HMW and Mr 220,000 neurofilament proteins after phosphorylation by ANF kinase or purified casein kinase I showed similar 32P-peptide patterns.
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PMID:Principal neurofilament-associated protein kinase in squid axoplasm is related to casein kinase I. 200 43

To determine the contribution of phosphate acceptor substrate to the pattern of activity of calcium-dependent, phospholipid-sensitive protein kinase (protein kinase C, PKC), we assayed cytosolic and particulate PKC activity for histone, troponin, myosin light chain (MLC), and endogenous cellular proteins in human neutrophils stimulated with phorbol myristate acetate (PMA), the chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) and synergistic stimulation with both agonists. In general, phosphotransferase activity in neutrophil subfractions toward troponin and endogenous proteins paralleled that toward histone, but MLC was a poor substrate for PKC and the pattern of phosphotransferase activity differed from that seen with the other substrates. Furthermore, the phosphorylation of endogenous neutrophil cytosolic proteins increased significantly after stimulation with FMLP, suggesting an endogenous cytosolic substrate(s) which increased in concentration following stimulation. We conclude that histone is a useful phosphate acceptor for study of PKC activity in human neutrophils, but substrate variability occurs and may influence interpretation of results in assays of PKC activity.
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PMID:Substrate dependence of human neutrophil protein kinase C. 205 46

Various pharmacological effectors were used to investigate the mechanism of arachidonic acid release by N-formyl-methionyl-leucyl-phenylalanine (fMLP) and platelet-activating factor (PAF) in guinea pig alveolar macrophages. The fMLP- and PAF-stimulated arachidonic acid release (i) was mimicked by sodium fluoride and inhibited by Bordetella pertussis toxin, suggesting the participation of a guanine nucleotide-binding protein; ii) was mimicked by A23187 but was insensitive to the calmodulin inhibitor R24571, making the involvement of a calmodulin-dependent pathway unlikely; and (iii) was mimicked by 12-O-tetra-decanoyl phorbol 13 acetate (TPA) and was, like the TPA-stimulated release, markedly decreased when protein kinase C (PKC) had been down-regulated by TPA (65% decrease) or inhibited by sphingosine, a diacylglycerol-competitive PKC inhibitor shown to completely abolish the enzyme activity from alveolar macrophages at 40 microM. Moreover, PAF and fMLP, under conditions where they stimulated arachidonic acid release, promoted an appreciable, albeit transient, translocation of PKC, suggesting a possible involvement of the enzyme in the agonist-stimulated process. However, staurosporine, another PKC inhibitor decreasing PKC activity from alveolar macrophages by 60% at 20 nM, failed to alter fMLP- and PAF-stimulated release. These data lead us to suggest that fMLP- and PAF-stimulated arachidonic acid release is mediated by mechanisms involving either a staurosporine-insensitive PKC isoform or a sphingosine-sensitive coupling between a pertussis toxin-sensitive guanine nucleotide-binding protein and phospholipase A2. Finally, the fMLP- and PAF-stimulated arachidonic acid release was inhibited by cholera toxin and was, like A23187-stimulated release, potentiated by N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H8), an exclusive protein kinase A inhibitor in alveolar macrophages, suggesting a negative regulation by protein kinase A.
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PMID:Mechanism of N-formyl-methionyl-leucyl-phenylalanine- and platelet-activating factor-induced arachidonic acid release in guinea pig alveolar macrophages: involvement of a GTP-binding protein and role of protein kinase A and protein kinase C. 211 77

In the Triton X-100-treated polymorphonuclear leukocytes (PMN), which were stimulated with formyl-Met-Leu-Phe (FMLP) for 1 min, a 64,000 molecular weight protein (p64) was preferentially phosphorylated by the incubation with [gamma-32P]ATP in the presence of Mg2+, but not in the presence of Ca2+. Phosphoamino acid analysis of pp64 revealed that the p64-kinase was a serine-specific protein kinase. The p64 was maximally phosphorylated in the first minute, suggesting that the rapid phosphorylation was related to the initial reaction for activation of the FMLP-stimulated PMN functions. The FMLP-stimulated phosphorylation of p64 was slightly inhibited by the addition of cGMP in the reaction mixture. However, addition of cAMP, the cyclic nucleotide-dependent kinase inhibitor (H-8), protein kinase C-inhibitor (H-7) or Ca/calmodulin-dependent kinase inhibitor (W-7), showed no effect on the phosphorylation. These data suggest that phosphorylation of p64 seems to be a novel protein kinase specific to p64.
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PMID:Formyl-Met-Leu-Phe-dependent serine kinase for a 64,000 molecular weight protein of polymorphonuclear leukocytes in a cell-lysate system. 214 31


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