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)

Regulation of the asparaginase activity rhythm in L. michotii has previously been shown to be dependent on a reversible phosphorylation process. Asparaginase was isolated as a purified protein complex having self-phosphorylating capacities, which were analyzed. In vivo phosphorylation of asparaginase complex was performed synchronously with the rhythm of asparaginase activity. In vitro self-phosphorylation of asparaginase complex resulted from the activity of an ATP-Mg2+-dependent protein kinase, which phosphorylated protein at threonine residues and was not dependent on cyclic AMP, Ca2+ or calmodulin. Dephosphorylation of this complex was due to a Mg2+-Zn2+-dependent protein phosphatase, molybdate inhibited, the specificity of which, for low-molecular-weight nonprotein phosphoesters, was broad.
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PMID:Reversible self-phosphorylation of asparaginase complex in Leptosphaeria michotii: characterization of associated protein kinase and protein phosphatase activities. 302 34

We have characterized protein phosphorylation in vitro in subcellular fractions from Drosophila melanogaster heads. Optimal conditions for the incorporation of 32P into proteins, and its dependence on ATP, divalent cations, and cyclic nucleotides have been determined, as well as the effect of inhibitors of ATPase, protein phosphatase, and protein kinase on protein phosphorylation. Among these inhibitors, Zn2+ was found to affect the incorporation of 32P into specific bands and p-hydroxymercuribenzoate was found to be most suited for freezing the activity of both kinases and phosphatases. Cyclic AMP-dependent protein kinase (cAMP-dPK) activity was present in both supernatant (S2) and particulate (P2) fractions, with the majority (60-85%, depending on the homogenization medium) being associated with S2, as determined by phosphorylation of exogenous synapsin I. cAMP-dPK catalyzed the phosphorylation of at least 18 endogenous polypeptides in S2 and at least 10 endogenous polypeptides in P2. These proteins could be classified on the basis of the extent of stimulation of phosphorylation by cyclic nucleotides, dependence on cyclic nucleotide concentration, and rate of phosphorylation. A phosphoprotein of 51 kilodaltons (pp51) was a major component of the S2 and P2 fractions and displayed properties expected from the regulatory subunit of the cAMP-dPK, R-II. A phosphoprotein doublet of approximately 37 kilodaltons (pp37) was stimulated to the largest extent by cAMP in the P2 and S2 fractions. The phosphorylation of several proteins in both fractions was significantly lowered by the mammalian Walsh inhibitor of cAMP-dPK, whereas in some cases the stimulation of phosphorylation of the same proteins by exogeneous cAMP was relatively small. Phosphoproteins from two learning mutants known to be deficient in cAMP metabolism, dnc and rut, were analyzed for their extent of phosphorylation in the presence of a stable cAMP analogue; no significant differences from normal were detected, suggesting that the genetic defect in cAMP metabolism is not accompanied by constituent abnormalities in phosphorylated substrates in the adult fly, and that the physiological defects in these mutants result from aberrations in the interaction of the cAMP cascade with normal substrates. The majority of Ca2+/calmodulin kinase activity (80-90%, depending on the homogenization procedure) was associated with S2, as revealed by phosphorylation of exogenous synapsin I. Two endogenous substrates for this kinase in P2 had molecular masses of approximately 45 and 87 kilodaltons. At least 11 substrates for the Ca2+/calmodulin-dependent kinase were detected in S2.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In vitro protein phosphorylation in head preparations from normal and mutant Drosophila melanogaster. 304 Sep 7

A protein kinase activity was identified in preparations of DNA-replicative complex from the budding yeast Saccharomyces cerevisiae. The activity phosphorylated only a few of the endogenous proteins in the replicative fraction, and it displayed a marked preference for a 48-kDa polypeptide. Despite this relative specificity, the protein kinase activity was capable of utilizing exogenously added histone as substrate. The 48-kDa polypeptide was phosphorylated on serine residue(s) exclusively by the endogenous activity in the replicative-complex preparation. The activity was not stimulated by cAMP, cGMP, Ca2+/phosphatidylserine/diacylglycerol, or Ca2+/calmodulin. It did not utilize Ca2+ or Zn2+ in the place of Mg2+, and Mn2+ was only 22% as effective in fulfilling the divalent-cation requirement. Most importantly, the protein kinase activity was heat-sensitive in replicative fractions from the cell division cycle 7 (cdc7) mutant, which arrests at or close to the G1/S boundary of the cell cycle at restrictive temperature. Thus, the activity is CDC7-dependent. An effect of heat treatment on replicating activity in the replicative fraction from cdc7 cells was also found. This result and the finding that the protein kinase activity copurified with replicating activity in the preparations suggest that the CDC7 gene product and the protein kinase activity, whether or not they are the same entity, interact with yeast replicative complex. All of these results raise the possibility that phosphorylation of components of the replication machinery may play a role in the control of initiation of DNA replication during the cell cycle. It is possible that the phosphorylation observed is part of a protein kinase cascade that regulates progress through the G1 phase of the cell cycle.
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PMID:CDC7-dependent protein kinase activity in yeast replicative-complex preparations. 328 Nov 61

Neurofilament (NF) protein kinase, partially purified from NF preparations [Toru-Delbauffe & Pierre (1983) FEBS Lett. 162, 230-234], was found to be distinct from both the casein kinase present in NFs and the cyclic AMP-dependent protein kinase which is able to phosphorylate NFs. NF-kinase phosphorylated the three NF protein components. The amount of phosphate incorporated per molecule was higher for NF 200 than for NF 145 and NF 68. Other proteins present in the NF preparations were also used as NF-kinase substrates. Two of them might correspond to the myelin basic proteins with Mr values of 18,000 and 21,000. Four other substrates in the NF preparation were not identified (respective Mr values 53,000, 55,000, 65,000 and greater than 300,000). NF kinase also phosphorylated two additional brain-cell cytoskeletal elements: GFAp and vimentin. Casein, histones and phosvitin, currently used as substrates for protein kinase assays, were very poor phosphate acceptors. Half-maximal NF-kinase activity was obtained at an NF protein concentration of about 0.25 mg/ml in heated, salt-washed, NF preparations. The specific activity was about 5 pmol of 32P incorporated/min per microgram of NF kinase preparation protein. ATP was a phospho-group donor (Km 8 X 10(-5) M), but GTP was not. NF-kinase activity remained stable at 65 degrees C for more than 1 h. The enzyme was not degraded by storage at -20 degrees C for several months in a buffer containing 50% (w/v) sucrose. Maximal activity was obtained with 5 mM-Mg2+ (Mg2+ could be replaced by Co2+); Zn2+ and Cu2+ inhibited the reaction. NF-kinase was not dependent on cyclic AMP, cyclic GMP, Ca2+ or Ca2+ plus dioleoylglycerol and phosphatidylserine.
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PMID:Properties of neurofilament protein kinase. 346 81

A novel protein kinase activity was characterized from the cytosolic fraction of isolated rabbit gastric glands. The kinase phosphorylated a major 33,000 Da endogenous protein (pp33) and was stimulated by Zn2+ and Mn2+ with Kact of 1.0 and 7.5 mM, respectively. Mg2+ and Ca2+ failed to stimulate any pp33 kinase activity. The kinase utilized both ATP and GTP as phosphate donors with a Km of 10 microM for both. The pp33 protein displayed an isoelectric point of 7.5 to 7.8 and was phosphorylated predominantly on threonine residues. The kinase activity is clearly differentiable from all reported kinase activities and appeared to be enriched in rabbit gastric fundic mucosa. The results indicate that gastric fundic mucosa contains a novel protein kinase activity.
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PMID:A novel protein kinase activity in rabbit gastric gland cytosol. 381 50

We have investigated the epidermal growth factor (EGF)-stimulated tyrosine-specific protein kinase activity in quiescent cultures of diploid human fibroblasts that have a well characterized mitogenic response to EGF. We developed a method of permeabilizing cells with digitonin or other agents that permitted the rapid labeling of cellular proteins with exogenously added [gamma-32P]ATP while allowing only about 25% of marker cytosolic enzymes to escape from the cells. When phosphatases were inhibited with zinc and vanadate, EGF induced up to 8-fold stimulation of the incorporation of radioactivity from [gamma-32P]ATP into a 35-kDa band on sodium dodecyl sulfate gels. Alkali treatment of gels showed that EGF stimulated the phosphorylation of bands with apparent molecular masses of 170, 45, 35, 26, 22, and 21 kDa. Phosphoamino acid analysis was performed on the 170- and 35-kDa bands and revealed that the EGF-stimulated phosphorylation was on tyrosyl residues. The 35-kDa band was resolved into four spots by two-dimensional gel electrophoresis. The most acidic form was the most prominent and it was precipitated by an antiserum against a 35-kDa protein from A-431 cells; heretofore, this protein has only been reported to be phosphorylated in an EGF-dependent manner by A-431 membranes in vitro (Fava, R. A., and Cohen, S. (1984) J. Biol. Chem. 259, 2636-2645). This antiserum also precipitated a 35-kDa phospho-protein from extracts of intact [32P]orthophosphate-labeled fibroblasts which was phosphorylated on tyrosine in an EGF-dependent manner. None of the forms of the 35-kDa phosphoproteins labeled in permeabilized cells were immunologically related to the 34-kDa protein that is a substrate for the tyrosyl kinase encoded by Rous sarcoma virus. Other mitogens (serum, insulin, platelet-derived growth factor, and thrombin) did not detectably stimulate phosphorylation in permeabilized cells.
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PMID:Epidermal growth factor stimulates tyrosine phosphorylation of specific proteins in permeabilized human fibroblasts. 387 22

Antibodies raised against the protein encoded by a lacZ-CDC28 in-frame fusion were shown to immunoprecipitate the CDC28 product from yeast cell lysates. The polypeptide p36CDC28 is a phosphoprotein of apparent Mr 36,000. Immune complexes prepared from yeast cell lysates by using anti-CDC28 antibody were found to possess a protein kinase activity, as determined by the transfer of label from [gamma-32P]ATP to a coprecipitated Mr 40,000 protein of unknown identity or function (p40). This activity was absent or thermolabile when extracts were prepared from several different cdc28 temperature-sensitive strains. The protein kinase activity was dependent on Zn2+ and transferred phosphate specifically to serine and threonine residues.
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PMID:Protein kinase activity associated with the product of the yeast cell division cycle gene CDC28. 388 21

Rat liver cytosol casein kinases 1 and 2 were stimulated by free Mg2+, but the optimal concentration of cation varied with both the casein kinase and the protein substrate used. Mn2+, but neither Ca2+ nor Zn2+, could efficiently substitute for Mg2+ in forming the bivalent-cation-ATP complex used as substrate, but free Mn2+ was inhibitory. The magnitude of these effects depended on the type of casein kinase and the protein substrate used. These results support the idea that, besides the effects of Mg2+ as a component of the Mg-ATP complex, or through interaction with the protein substrate, free Mg2+ is an allosteric effector of both casein kinases.
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PMID:Effect of bivalent cations on rat liver cytosol casein (glycogen synthase) kinases 1 and 2. Influence of the protein substrate. 393 31

Coated vesicles prepared from bovine brains contained a protein kinase activity which catalyzed the phosphorylation of endogenous structural proteins, Mr 150 000, 120 000, 48 000 and 32 000. An endogenous protein, Mr 48 000 was most strongly phosphorylated by this kinase. This protein kinase also phosphorylated exogenous proteins, phosvitin intensely and casein slightly but not histone or protamine. The enzyme activity was independent of cyclic nucleotides or Ca2+/calmodulin. Mg2+ stimulated the kinase activity. Some divalent cations were substituted for Mg2+; the potency decreased in the order Mn2+, Mg2+, Co2+, Ca2+, Zn2+. Two separate subfractions, the outer coat and the inner vesicle (core), were prepared from coated vesicles by a urea treatment followed by sucrose density gradient centrifugation and dialysis. The kinase activity was found predominantly in the coat subfraction.
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PMID:Protein kinase and its endogenous substrates in coated vesicles. 614 72

Epidermal growth factor stimulates a cyclic AMP-independent protein kinase associated with membrane vesicles derived from human epidermoid carcinoma cells (Carpenter, G., King, L., Jr., and Cohen, S. (1979) J. Biol. Chem. 254,. 4884-4891). The kinase specifically phosphorylates tyrosyl residues in a Mr = 150,000 membrane protein (Ushiro, H., and Cohen, S. (1980) J. Biol. Chem. 255, 8363-8365). We show that the reverse reaction, catalyzed by a phosphotyrosyl-protein phosphatase associated with the membrane, is inhibited by Zn2+. Dephosphorylation of phosphotyrosyl residues in the Mr = 150,000 protein is completely inhibited by Zn2+ at concentrations as low as 10 microM, whereas other divalent cations have no substantial effect. Inhibition of the phosphatase was reversed by EDTA and the activity in membrane preparations was increased by EDTA or fluoride, agents commonly thought to be phosphatase inhibitors. Acid hydrolysis of the membrane proteins followed by analysis of phosphoamino acids by two-dimensional electrophoresis revealed that the phosphatase hydrolyzed phosphotyrosyl in preference to phosphoseryl residues. The specific inhibition of this phosphatase activity by low concentrations of Zn2+ may be indicative of the physiological importance of Zn2+ in the regulation of cellular phosphotyrosyl-protein levels.
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PMID:Phosphotyrosyl-protein phosphatase. Specific inhibition by Zn. 616 21


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