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)

Translocation of Ca2+/phospholipid-dependent protein kinase (PKC) activity from cytosolic to membrane fractions was assessed in washed human platelet suspensions. Phorbol myristate acetate (PMA) induced a rapid loss of PKC activity from the cytosolic compartment in stirred platelets, which was not accompanied by measurable increases in membrane-associated activity, but was paralleled by a decrease in total cellular enzyme activity (cytosol plus membrane). When platelet aggregation was prevented by not stirring, (i) cytosolic activity was decreased by PMA, (ii) significant and maintained (1-15 min with PMA) increases in membrane-bound PKC were detected, and (iii) the decline in total enzyme activity was markedly slower. In stirred platelets, total and specific inhibition of PMA-induced aggregation by a fibrinogen-derived peptide (RGDS, i.e. Arg-Gly-Asp-Ser) promoted maximal increases in membrane-associated PKC in the presence of PMA and completely prevented the loss in cellular activity. Thrombin and collagen both induced a decrease in cytosolic PKC and a loss of total activity, but a significant rise in membrane activity was seen only with collagen; ADP had no detectable effect on enzyme distribution. These results demonstrate an agonist-induced redistribution of PKC and indicate that platelet aggregation may play an important role in the proteolysis, and hence persistence, of membrane-associated PKC. This observation has implications for the potency and duration of PKC-mediated responses induced by agonists and exogenous PKC activators.
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PMID:Receptor- and phorbol-ester-mediated redistribution of protein kinase C in human platelets. Evidence that aggregation promotes degradation of protein kinase C. 259 39

A 40-kDa fragment of chicken smooth muscle myosin light chain kinase was produced and partially purified from a bacterial expression system. This fragment exhibits calmodulin binding and substrate phosphorylation properties similar to those of the isolated chicken gizzard enzyme. A series of 3'-deletion mutants was prepared and used to produce proteins with the same NH2 terminus but with COOH termini varying over 180 amino acids. Results show that truncation of the enzyme at Ser-512 (based on the amino acid numbering system described for the partial cDNA clone by Guerriero, V., Jr., Russo, M. A., Olson, N. J., Putkey, J. A., and Means, A. R. (1986) Biochemistry 25, 8372-8381) does not alter calmodulin binding, calmodulin regulation, or enzymatic properties. Removal of an additional 5 residues from the COOH terminus completely inhibits calmodulin binding and results in an inactive kinase that can be fully activated by limited proteolysis. Site specific mutations within these 5 residues demonstrate that Gly-508 and Arg-509 are independently involved in calmodulin-dependent binding and activation of myosin light chain kinase. Truncation of the enzyme at residues within the protein kinase catalytic domain results in inactive protein that cannot be activated by proteolysis.
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PMID:Myosin light chain kinase structure function analysis using bacterial expression. 267 19

A cDNA clone for the catalytic subunit of murine cAMP-dependent protein kinase was placed into two expression vectors, pLWS-3 and pLSW-4. For pLWS-3, the entire coding region of the catalytic subunit was inserted into the NdeI site of pT7-7 under the control of the T7 promoter. pLWS-4 contains a polycistronic transcript under control of the lac UV5 promoter encoding for the type I regulatory subunit followed by the catalytic subunit. Significant expression was achieved with pLWS-4 in Escherichia coli 222 and JM101; however, the catalytic subunit was produced in an insoluble form. In the case of the catalytic subunit produced in E. coli BL21(DE3) by pLWS-3, the catalytic subunit accounted for approximately 30% of the total bacterial protein. Up to 5 mg of this catalytic subunit per liter of culture was in the soluble extract. Solubility was improved substantially when induction was carried out at 30 degrees C instead of 37 degrees C. This recombinant catalytic subunit was purified by phosphocellulose chromatography, followed by ammonium sulfate precipitation and gel filtration. A Mr of 38,000 was estimated based on size exclusion chromatography and on polyacrylamide gel electrophoresis. The recombinant protein had a free alpha-amino-terminal Gly in contrast to the mammalian enzyme which is myristylated at the amino-terminal glycine. The lack of acylation did not significantly alter the activity of the enzyme. The specific activity of 19 mumol/min/mg is comparable to the mammalian enzyme. The Km values for Kemptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly) (43 microM) and MgATP (18.5 microM also were comparable. The absence of the acyl group also did not prevent holoenzyme formation. Holoenzyme activation by cAMP was indistinguishable for holoenzyme made with mammalian catalytic subunit and recombinant catalytic subunit. The recombinant enzyme was more sensitive than the mammalian enzyme to heat denaturation at 49 degrees C. The t1/2 for the recombinant catalytic subunit was 0.7 min in contrast to 3.9 min for the mammalian enzyme. This difference in stability may be attributable to the lack of the acyl group. The recombinant enzyme was particularly sensitive to heat denaturation in the presence of low concentrations (0.01%) of Triton X-100.
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PMID:Expression of the catalytic subunit of cAMP-dependent protein kinase in Escherichia coli. 268 67

PKI-(5-24)-amide is a 20-residue peptide with the sequence, Thr5-Thr-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-A la-Ile-His- Asp24-NH2, that corresponds to the active portion of the heat-stable inhibitor protein of cAMP-dependent protein kinase (Cheng, H.-C., Kemp, B. E., Pearson, R. B., Smith, A. J., Misconi, L., Van Patten, S. M., and Walsh, D. A. (1986) J. Biol. Chem. 261, 989-992). Amino acid residues in PKI-(5-24)-amide responsible for the potent inhibition (Ki = 2.3 nM) of the catalytic subunit of protein kinase were further investigated using deletion and substitution analogs of the synthetic peptide. Residues 5, 23, and 24 were not required for activity since the 17-residue PKI-(6-22)-amide retained full potency. Sequential removal of the first seven amino acids from the NH2 terminus of PKI-(5-24)-amide caused a progressive 50-fold loss of inhibitory potency. In contrast, substitution of either Thr6, Asp9, or Ile11 with alanine, or Ala8 by leucine, in PKI-(5-22)-amide produced less than 3-fold decreases in potency. Of the 2 aromatic residues in PKI-(5-22)-amide, the individual substitution of Phe10 and Tyr7 by alanine caused, respectively, 90- and 5-fold decreases in inhibitory potency, demonstrating important roles for each. This NH2-terminal portion of the peptide is believed to contain a significant portion of alpha-helix. Many recognition or structural determinants are also essential in the COOH-terminal portion of PKI-(5-22)-amide. In addition to the basic subsite provided by the three arginines, several other of the residues are critical for full inhibitory potency. Substitution of Ile22 by glycine in either PKI-(5-22)-amide or PKI-(14-22)-amide lowered the inhibitory potency by 150- and 50-fold, respectively. Separate replacement of Gly17 or Asn20, in either PKI-(5-22)-amide or PKI-(14-22)-amide, caused 7-15-fold decreases in potency. Substitution of both Gly17 and Asn20 together (in PKI-(14-22)-amide) produced a synergistic loss of inhibitory activity. [Leu13,Ile14]PKI-(5-22)-amide, a doubly substituted analog exhibited a 42-fold increase in Ki value. We conclude that Ser13 and/or Gly14, Gly17, Asn20, and Ile22 each contribute important features to the binding of these inhibitory peptides to the protein kinase, either by providing recognition determinants, inducing structure, and/or allowing essential peptide backbone flexibility.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Primary structural determinants essential for potent inhibition of cAMP-dependent protein kinase by inhibitory peptides corresponding to the active portion of the heat-stable inhibitor protein. 272 99

The minimal structure in the heat-stable inhibitor protein of cAMP-dependent protein kinase required for a low nanomolar potency of inhibition is the peptide Thr6-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-+ ++Ile22-NH2 (PKI-(6-22)-amide). While primary structural determinants for interaction with the protein kinase are distributed throughout the 17 residues of this peptide, we have previously shown that phenylalanine 10 in the NH2-terminal portion is a particularly important determinant for high affinity binding (Glass, D. B., Cheng, H.-C., Mende-Mueller, L., Reed, J., and Walsh, D. A. (1989) J. Biol. Chem. 264, 8802-8810). To investigate this requirement further, peptide analogs of PKI-(6-22)-amide in which various natural and nonstandard amino acids are substituted for phenylalanine 10 have been synthesized and tested for inhibitory potency against the catalytic subunit of the protein kinase. Consistent with the importance of the hydrophobicity of phenylalanine, an alanine 10 substitution analog exhibited a 270-fold decrease in inhibitory potency, whereas the leucine 10 analog lost only 33-fold in activity as compared to the parent peptide PKI-(6-22)-amide. Peptides containing the spatial conformation analogs D-phenylalanine, homophenylalanine, or phenylglycine were 60-120-fold less potent than the parent peptide. Peptides containing various para-substituted phenylalanines at position 10 were only 5-11-fold less potent. One exception to this was (4'-azidophenylalanine 10)PKI-(6-22)-amide, which was nearly equipotent with the parent inhibitor. The most potent analogs were those peptides containing highly aromatic residues at position 10. The 2'-thienylalanine 10, tryptophan (formyl) 10, tryptophan 10, and the 1'-naphthylalanine 10 analogs were 3-fold less potent, equipotent, slightly more potent, and 4-fold more potent than the parent peptide inhibitor, respectively. We conclude that phenylalanine 10 in PKI-(6-22)-amide, and presumably in the native protein inhibitor, interacts through specific hydrophobic and/or aromatic binding to a hydrophobic pocket or cleft near the active site of the protein kinase.
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PMID:Protein kinase inhibitor-(6-22)-amide peptide analogs with standard and nonstandard amino acid substitutions for phenylalanine 10. Inhibition of cAMP-dependent protein kinase. 276 75

The amino acid sequence of a region on chromosomal protein HMG-I from human cells that is phosphorylated by casein kinase II has been determined. The sequence is: Leu-Glu-Lys-Glu-Glu-Glu-Glu-Gly-Ile-Ser-Gln-Glu-Ser(P)-Ser(P)-Glu-Glu-Gl u-Gln. It corresponds to the C-terminal residues 90-107 of HMG-I [(1989) Mol. Cell. Biol. 9, 2114-2123]. Sequence analysis of the native peptide (90-107) after treatment, which specifically converts phosphoserine residues to S-ethylcysteine, revealed that 70-80% of serine residues 102 and 103 were phosphorylated in vivo. Both residues were fully phosphorylated in vitro by incubation with casein kinase II. These results suggest that casein kinase II is involved in the regulation of HMG-I function in the cells.
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PMID:Identification of sites on chromosomal protein HMG-I phosphorylated by casein kinase II. 280 54

The pH dependence of kinetic parameters and inhibitor dissociation constants for the adenosine cyclic 3',5'-monophosphate dependent protein kinase reaction has been determined. Data are consistent with a mechanism in which reactants selectively bind to enzyme with the catalytic base unprotonated and an enzyme group required protonated for peptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly) binding. Binding of the peptide apparently locks both of the above enzyme residues in their correct protonation state. MgATP preferentially binds fully ionized and requires an enzyme residue (probably lysine) to be protonated. The maximum velocity and V/KMgATP are pH independent. The V/K for Ser-peptide is bell-shaped with pK values of 6.2 and 8.5 estimated. The pH dependence of 1/Ki for Leu-Arg-Arg-Ala-Ala-Leu-Gly is also bell-shaped, giving pK values identical with those obtained for V/KSer-peptide, while the Ki for MgAMP-PCP increases from a constant value of 650 microM above pH 8 to a constant value of 4 mM below pH 5.5. The Ki for uncomplexed Mg2+ obtained from the Mg2+ dependence of V and V/KMgATP is apparently pH independent.
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PMID:Chemical mechanism of the adenosine cyclic 3',5'-monophosphate dependent protein kinase from pH studies. 282 Apr 83

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

Four mutants with amino acid substitution(s) at or near the putative phosphorylation site (Arg142 Arg143 Thr144 Ser145) of the regulatory subunit of cAMP-dependent protein kinase were obtained by site-directed mutagenesis. Three mutants, BCY1A1a145 (Ser145 to Ala), BCY1His143 (Arg143 to His) and BCY1Asn144, Ala145 (Thr144 to Asn and Ser145 to Ala) complemented a bcy1 mutant, whereas BCY1Gly143 (Arg143 to Gly) did not. In addition, mutant, BCY1Asn144, Ala145 exhibited a dominant cold-sensitive phenotype, which can be most easily explained by the functional alteration of the regulatory subunit of cAMP-dependent protein kinase by the mutations. Analyses of these mutant genes revealed that phosphorylation of the regulatory subunit is not a prerequisite for the regulation of the cAMP-dependent protein kinase activity in responding to the cAMP level.
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PMID:Mutant regulatory subunit of 3',5'-cAMP-dependent protein kinase of yeast Saccharomyces cerevisiae. 282 90

A combination of metabolic labeling and chemical or enzymatic modification was employed to isolate and biochemically characterize a set of glycosyl-phosphatidylinositol (gly-PI) molecules synthesized by T lymphocytes. Gly-PI displayed unique patterns of synthesis following mitogen activation relative to the phosphoinositides and major structural lipids. The increase with time in gly-PI was paralleled by the appearance of insulin receptors. Gly-PI molecules were sensitive to hydrolysis by a PI-specific phospholipase C and were rapidly (15 sec) degraded in response to insulin binding. The product of this hydrolysis is believed to be a novel inositol phosphate-glycan (IP-gly) that was shown to inhibit the activity of a cAMP-dependent protein kinase. These results demonstrate that T cells contain a structurally related set of gly-PI molecules, at least one of which is sensitive to insulin and may function as a second messenger of hormone action.
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PMID:Regulation and function of an insulin-sensitive glycosyl-phosphatidylinositol during T lymphocyte activation. 283 76


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