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)

The authors have previously observed that glucocorticoids dramatically increase the number of interleukin 1 (IL-1) receptors on normal human peripheral blood mononuclear cells (PBMC) (from approximately 100 to 2000 receptors/cell) without significant change in the binding affinity (Kd = approximately 2.6 x 10(-10) M). We, therefore, used such a receptor-enriched glucocorticoid-pretreated PBMC to investigate whether IL-1 induces/increases the phosphorylation of any cell-associated proteins, including possible autophosphorylation of IL-1 receptors. Extraction of 125I-labeled IL-1 alpha cross-linked to IL-1 receptor on steroid-treated PBMC yielded two bands estimated to be 60 and 70 kDa in molecular mass. No molecules were significantly cross-linked with 125I-labeled IL-1 alpha on untreated PBMC. Carrier-free recombinant human IL-1 alpha induced phosphorylation of an acidic 65-kDa protein (pp65) at serine residues within 5 min more effectively in glucocorticoid-treated PBMC than in untreated PBMC. Fractionation of extracts of IL-1-stimulated prednisolone-pretreated PBMC by ultracentrifugation showed that pp65 is located in the cytosol, suggesting that pp65 is not the IL-1 receptor itself. Protein kinase inhibitors, HA1004 and W-7, but not H-7, significantly inhibited the induction of the phosphorylation of 65-kDa protein by IL-1. These data indicate that the glucocorticoid-induced IL-1 receptor is functional and either contains or is closely associated with a serine kinase that is distinct from protein kinase C.
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PMID:Phosphorylation of a cytosolic 65-kDa protein induced by interleukin 1 in glucocorticoid pretreated normal human peripheral blood mononuclear leukocytes. 296 Jul 34

Insulin-stimulated protein kinase activities detected in Xenopus oocyte membrane were examined. The plasma membrane proteins solubilized in a buffer containing Triton X-100 were immunoprecipitated with anti-phosphotyrosine antibodies and adsorbed materials were eluted with a buffer containing p-nitrophenyl phosphate. The eluate contained protein serine kinase activity toward H1 histone which was increased 2-3 fold by insulin. Protein tyrosine kinase activity was also exhibited in Xenopus oocyte membrane and the close parallel to serine kinase activity was observed in response to insulin. These results suggest that insulin-stimulated serine kinase is activated through the phosphorylation by protein tyrosine kinase.
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PMID:Insulin-stimulated serine kinase in Xenopus oocyte plasma membrane. 296 34

K+ at high concentrations (52-72 mM hypertonic KCl) has been reported to induce reverse transformation in the 6m2 cell, which is a clone of normal rat kidney cells (NRK) infected with a temperature-sensitive transformation virus. When exposed to high K+, 6m2 cells grown at the permissive temperature (33 degrees C) exhibit normal morphology and reduced soft agar growth, characteristics of cells grown at nonpermissive temperature (39 degrees C). In the current study, flattening of cells and rearrangement of surface microvilli were demonstrated by scanning electron microscopy to occur within 6 hr of exposure to high K+, similar to the effect of temperature shift to 39 degrees C. Exposure to K+ resulted in a 90% inhibition of P85gag-mos-associated serine kinase activity within 5 min, with a subsequent reduction of up to 75% of the synthesis of this protein. These alterations in the putative transforming protein were similar to those induced by temperature shift and were considered to be the basis for retrotransformation. The cell microtubular system and F-actin cables were affected more slowly by K+ than by a temperature shift to 39 degrees C. The former did not achieve the fine reticulum network seen in NRK cells until 72 hr later, but the latter remained aberrant. The effect on the enzyme might be mediated by alteration in phosphorylation, but the mechanism by which kinase inactivation induces retrotransformation is not yet known.
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PMID:Potassium inhibition of transforming protein P85gag-mos and reversal of the transformed phenotype in 6m2 cells. 296 57

Two systems in vitro are described that show insulin-stimulated phosphorylation of the insulin receptor on serine residues. In the first system, insulin receptor was purified partially from Fao rat hepatoma cells by direct solubilization of the cells in Triton X-100 and chromatography on wheat-germ-agglutinin-agarose. Phosphorylation of these preparations with [gamma-32P]ATP in the presence or absence of insulin resulted in 32P incorporation exclusively into phosphotyrosine residues. Serine kinase activity towards the insulin receptor was reconstituted by adding extracts of Fao cells. Prior exposure of the cells to insulin stimulated serine kinase activity towards the insulin receptor in extracts 7.2-fold. A receptor serine kinase activity enhanced by treatment of cells with cyclic AMP analogues was also retained in the reconstituted system. In the second system, insulin receptor and insulin-sensitive serine kinase activity towards the insulin receptor were co-purified from human placenta. The protocol involved preparation of membranes, before solubilization and chromatography on wheat-germ-agglutinin-agarose, by using gentle procedures designed not to disrupt a potentially labile association between the insulin receptor and the serine kinase. Serine kinase activity in these preparations towards the insulin receptor was stimulated up to 10-fold by insulin, and the stoicheiometry of serine phosphorylation was estimated to be approx 0.8 mol/mol of insulin receptor for phosphorylations performed in the presence of insulin. Thus a preparation of insulin receptor is described for the first time that is phosphorylated to high stoicheiometry on serine in an insulin-dependent manner. Conditions that facilitate recovery and assay of serine kinase activity are defined and discussed. These systems provide a basis for characterizing the nature of the insulin-sensitive serine kinase that phosphorylates the insulin receptor, and defining its role in insulin action and control of receptor function.
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PMID:Two systems in vitro that show insulin-stimulated serine kinase activity towards the insulin receptor. 296 79

The synthesis and testing of potential multisubstrate inhibitors of tyrosine-specific protein kinases are described. One of the substrates, ATP, was mimicked by the known kinase inhibitor 5'-[4-(fluorosulfonyl)benzoyl]adenosine, which was covalently linked via the sulfonyl moiety to tyrosine mimics. The resulting multisubstrate inhibitors were tested for their ability to inhibit the transfer of phosphate from ATP to a protein acceptor by p60v-abl, the tyrosine kinase encoded by the transforming gene (v-abl) of the Abelson murine leukemia virus (A-MuLV). Although the series of inhibitors displayed moderately potent activity (IC50 values as low as 19 microM), the absence of large effects produced by modification of the tyrosine mimic suggests that they do not behave as multisubstrate inhibitors but bind primarily through the adenosine moiety common to all the inhibitors. This interpretation is strengthened by the finding that the inhibitors lack specificity, inhibiting a serine kinase at comparable concentrations.
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PMID:Synthesis and evaluation of multisubstrate inhibitors of an oncogene-encoded tyrosine-specific protein kinase. 1. 297 May 50

Exposure of A-431 cells to epidermal growth factor (EGF) results in a rapid enhancement (approximately 10-fold) of cytosolic serine protein kinase activity. The increase in serine kinase activity may be detected using a number of peptide and protein substrates. Enhancement of kinase activity occurs within 1 min of exposure of the cells to EGF and reaches a maximum in 5 min. Similar results were obtained with a variety of cell lines. We have partially purified the EGF-activated kinase from A-431 cells. It has an apparent molecular mass of approximately 100 kDa by gel filtration. One distinguishing property of the enzyme is its sensitivity to inhibition by micromolar quantities of polyarginine; polylysine has no effect. The EGF-activated kinase is unaffected by cyclic nucleotides, Ca2+/calmodulin, Ca2+/diolein/phosphatidylserine, or heparin. The enhancement of cytosolic serine kinase activity in A-431 cells appears to be an early event in cell "activation" by a number of biological response modifiers including EGF, bradykinin, 12-O-tetradecanoylphorbol-13-acetate, and histamine.
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PMID:Activation of a cytosolic serine protein kinase by epidermal growth factor. 297 35

Insulin receptor was co-purified from human placenta together with insulin-stimulated kinase activity that phosphorylates the insulin receptor on serine residues. By using this 'in vitro' system, the mechanism of activation of the serine kinase by insulin was explored. Peptide 1150, histone, poly(Glu-Tyr), eliminating Mn2+ (Mg2+ only), treatment at 37 degrees C (1 h), N-ethylmaleimide, phosphate, beta-glycerol phosphate and anti-phosphotyrosine antibody all inhibited insulin-receptor tyrosine kinase activity and the ability of insulin to stimulate phosphorylation of the insulin receptor on serine. Additionally, direct stimulation of the receptor tyrosine kinase by vanadate increased serine phosphorylation of the insulin receptor. Insulin-stimulated tyrosine phosphorylation preceded insulin-stimulated serine phosphorylation of the insulin receptor. The activity of the insulin-sensitive receptor serine kinase was not augmented by cyclic AMP, cyclic GMP, Ca2+, Ca2+ + calmodulin, Ca2+ + phosphatidylserine + diolein or spermine, or inhibited appreciably by heparin. Additionally, the serine kinase phosphorylated casein or phosvitin poorly and was active with Mn2+. This indicates that it is distinct from Ca2+, Ca2+/phospholipid, Ca2+/calmodulin, cyclic AMP- and cyclic GMP-dependent protein kinases, casein kinases I and II and insulin-activated ribosomal S6 kinase. Taken together, these data indicate that a novel species of serine kinase catalyses the insulin-dependent phosphorylation of the insulin receptor and that activation of this receptor serine kinase by insulin requires an active insulin-receptor tyrosine kinase.
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PMID:Evidence that a novel serine kinase catalyses phosphorylation of the insulin receptor in an insulin-dependent and tyrosine kinase-dependent manner. 297 46

An antiserum directed against amino acid residues 37-55 [anti-mos (37-55) serum] of the predicted v-mos sequence was used to precipitate p37mos from Moloney murine sarcoma virus-124 (Mo-MuSV-124) acutely infected 3T3 cells. Proteins with sizes ranging from p37mos to 43 kDa (p43) were found to be phosphorylated when anti-mos (37-55) immune complexes containing p37mos were incubated with [gamma-32P]ATP and Mn2+. The phosphorylation of p37mos and p43 could be specifically blocked when the anti-mos (37-55) serum was incubated with 37-55 cyclic mos peptide prior to immunoprecipitation, but not if the serum was preincubated with an unrelated peptide representing amino acids of the myc protein sequence. Anti-mos (37-55) immune complexes from uninfected 3T3 cells did not produce any phosphorylated proteins the size of p37mos or p43. However, a 50-kDa protein (p50) was phosphorylated in both unblocked and mos peptide-blocked anti-mos (37-55) immune complexes from infected 3T3 cells, and in immune complexes from uninfected cells. Quercetin, an inhibitor of some protein kinases, inhibited the kinase phosphorylating p50 but not the kinase phosphorylating p37mos and p43. Preabsorption of the cell extract prior to immunoprecipitation with an excess of formalin-fixed Staphylococcus aureus, complexed with preimmune normal rabbit serum IgG, specifically removed the kinase phosphorylating p50. The amount of in vitro phosphorylated p37mos and p43 in the immune-complex kinase assay reached a maximum in extracts of 3T3 cells 2-3 days postinfection with Mo-MuSV 124 but decreased to trace levels after 5 days. Metabolically and in vitro phosphorylated p37mos generated an identical pattern of phosphopeptides upon partial V8 protease digestion. Based on peptide mapping and a kinetic analysis of the in vitro phosphorylation reaction, p37mos appears to be a precursor to the p43 phosphorylated species. Phosphoamino acid analyses revealed only phosphoserine in in vitro phosphorylated p37mos and p43mos. It was concluded that p37mos is closely associated with a serine kinase activity and that the in vitro phosphorylation of p37mos may lead to formation of a highly modified mos protein (p43) by way of superphosphorylation.
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PMID:Serine kinase activity associated with Maloney murine sarcoma virus-124-encoded p37mos. 299 8

The insulin receptor is an integral membrane glycoprotein (Mr approximately 300,000) composed of two alpha-subunits (Mr approximately 130,000) and two beta-subunits (Mr approximately 95,000) linked by disulphide bonds. This oligomeric structure divides the receptor into two functional domains such that alpha-subunits bind insulin and beta-subunits possess tyrosine kinase activity. The amino acid sequence deduced from cDNA of the single polypeptide chain precursor of human placental insulin receptor revealed that alpha- and beta-subunits consist of 735 and 620 residues, respectively. The alpha-subunit is hydrophilic, disulphide-bonded, glycosylated and probably extracellular. The beta-subunit consists of a short extracellular region which links the alpha-subunit through disulphide bridges, a hydrophobic transmembrane region and a longer cytoplasmic region which is structurally homologous with other tyrosine kinases like the src oncogene product and EGF receptor kinases. The cellular function of insulin receptors is dual: transmembrane signalling and endocytosis of hormone. The binding of insulin to its receptor on the cell membrane induces transfer of signal from extracellular to cytoplasmic receptor domains leading to activation of cell metabolism and growth. In addition, hormone-receptor complexes are internalized leading to intracellular proteolysis of insulin, whereas receptors are recycled to the membrane. These phenomena are kinetically well-characterized, but their molecular mechanisms remain obscure. Insulin receptor in different tissues and animal species are homologous in their structure and function, but show also significant differences regarding size of alpha-subunits, binding kinetics, insulin specificity and receptor-mediated degradation. We suggest that this heterogeneity of receptors may be linked to the diversity in insulin effects on metabolism and growth in various cell types. The purified insulin receptor phosphorylates its own beta-subunit and exogenous protein and peptide substrates on tyrosine residues, a reaction which is insulin-sensitive, Mn2+-dependent and specific for ATP. Tyrosine phosphorylation of the beta-subunit activates receptor kinase activity, and dephosphorylation with alkaline phosphatase deactivates the kinase. In intact cells or impure receptor preparations, a serine kinase is also activated by insulin. The cellular role of two kinase activities associated with the insulin receptor is not known, but we propose that the tyrosine- and serine-specific kinases mediate insulin actions on metabolism and growth either through dual-signalling or sequential pathways.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Protein kinase activity of the insulin receptor. 301 97

Insulin responsive protein kinase activities of wheat germ purified glycoproteins were examined. Glycoproteins were first incubated without or with insulin, and then exposed to a serum containing antibodies to insulin receptor. Thereafter, both immunoprecipitates and supernatants were studied for their kinase activity toward histone. Incubation with anti receptor antibodies promoted insulin receptor beta subunit and histone phosphorylation. More important insulin receptor depleted extract contained a kinase activity toward histone, that was increased by preincubation with insulin. This stimulation was observed only when insulin was added before the immunoprecipitation of insulin receptors. Alkali treatment and phosphoamino acids analysis revealed that the kinase activity remaining in the supernatant is serine specific. These findings suggest, that a serine kinase activity is associated with the insulin receptor, that it can be separated from the insulin receptor with anti receptor antibodies, that the serine kinase is activated by the hormone-receptor complex.
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PMID:Presence of an insulin-stimulated serine kinase in cell extracts from IM-9 cells. 302 Nov 23


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