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)

A variety of effects of cyclic AMP on cellular and subcellular phenomena suggest that there may be other modes of action of cyclic AMP then activation of protein kinase. It is also known that developing embryos contain cyclic AMP and its related enzymes. In order to explore the role of cyclic AMP in embryogenesis, a survey of proteins capable of binding cyclic AMP in the embryonic supernatant of Drosophila melanogaster was carried out. As the result, two cyclic AMP-binding proteins were found and characterized. The one (L) is, as expected, associated with protein kinase and has a dissociation constant of about 10(-9) M. Its molecular weight of 21 000 daltons is extremely small when compared with similar proteins in other organisms. The other (H), whose function is yet to be found, has a molecular weight of about 200 000 daltons and has a dissociation constant of about 10-7 M. Some laxity in binding specificity of the latter protein among adenosine nucleotides was observed, but cyclic AMP is the strongest ligand among them.
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PMID:Cyclic AMP binding proteins in early embryos of Drosophila melanogaster. 16 85

Dibutyryl cyclic AMP and theophylline kill S49.1 mouse lymphoma tissue culture cells. When cells are grown in soft agar with these drugs, the few clones that survive are resistant to cytolysis. The rate of mutation to resistance is 1-3 times 10-7/cell/generation in both diploid and tetraploid cells. The incidence of mutants is increased by treatment with a chemical mutagen, ICR 191. The mutation is consistently associated with greatly reduced or absent cytoplasmic cyclic AMP binding protein. These results suggest that a somatic mutation leads to a defect of the protein kinase regulatory subunit and that activity of this kinase is required for induction of cell death by cyclic AMP.
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PMID:Somatic genetic analysis of cyclic AMP action: selection of unresponsive mutants. 16 36

N-6,O-2'-dibutyryl adenosine 3',5'-monophosphate kills cultured mouse lymphosarcoma cells, but not resistant mutants derived by a single-step clonal selection. Resistant clones lack the cyclic AMP binding proteins present in wild type, cyclic AMP sensitive clones. Both endogenous cyclic AMP, accumulated in response to isoproterenol or cholera toxin, and exogenous dibutyryl cyclic AMP induce cyclic AMP phosphodiesterase, slow growth, and eventually kill wild type cells. In the resistant mutants, however, the endogenous and exogenous cyclic nucleotides appear to be completely inactive. These results indicate that an intracellular receptor for cyclic AMP, previously shown to be associated with a cyclic AMP-dependent protein kinase, mediates cyclic AMP's regulation of growth and phosphodiesterase synthesis.
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PMID:Somatic genetic analysis of cyclic AMP action: characterization of unresponsive mutants. 16 37

Cyclic adenosine monophosphate (cyclic AMP) and 11 derivatives were applied to rat cerebellar Purkinje cells by iontophoresis. Cyclic AMP inhibited 63 percent of the cells, while the 8-parachlorophenylthio- and 8-benzylthio- analogs of cyclin AMP inhibited the spontaneous firing of 92 and 89 percent of cells, respectively. The ability of the 11 analogs to inhibit neuronal firing correlated ( r= + .78) with their reported potency in activating cyclic AMP-dependent protein kinase. These results extend previous studies, pointing to the mediation by cyclic AMP of the noradrenergic inhibition of Purkinje neurons, and provide new physiological evidence that protein phosphorylation is a major step in the action of cyclic AMP.
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PMID:Analogs of cyclic adenosine monophosphate: correlation of inhibition of Purkinje Neurons with Protein Kinase Activation. 16 39

Endogenous and hormone-induced protein (polypeptide) phosphorylations were studied in isolated rat fat cells, in fat pads, and in subcellular fractions obtained from fat tissue under different physiological conditions. Insulin (25-100 muU/ml) increased the incorporation of 32P into two proteins: insulin-phosphorylated proteins (IPP 140 and IPP 50; similar to 140,000 and 50,000 daltons, respectively). Epinephrine (10(-7)-10(-6) M) increased the incorporation of 32P into another protein: epinephrine-phosphorylated protein (EPP 60-65; similar to 60,000-65,000 daltons). Endogenous IPP 140 phosphorylation in fat cells obtained from fasted and refed rats was similar to that of insulin in normal cells. Studies of insulin and epinephrine interactions showed that insulin increased IPP 140 phosphorylation even in the presence of epinephrine or lithium (25 mM times 10(-3) M). dibutyryl cyclic AMP (5 times 10(-4) M) markedly stimulated EPP 60-65 phosphorylation, but neither epinephrine (10(-7)-10(-6) M) nor dibutyryl cyclic AMP reproduced insulin's phosphorylation of APP 140. Lithium inhibited both endogenous and epinephrine-stimulate EPP 60-65 phosphorylation, but did not inhibit that induced by dibutyryl cyclic AMP. These findings suggest that insulin stimulated a specific, cyclic AMP independent protein kinase for IPP 140 phosphorylation. Cell-free extracts from insulin-treated fat tissue catalyzed the specific transfer of 32P from ATP to IPP 140 more rapidly than control extracts. No differences in the total receptor protein or total protein kinase activity using [gamma(-32P]ATP were noted between insulin-treated and control preparations. IPP 140 may be either (a) an insulin-sensitive protein kinase (phosphotransferase) or (b) a protein whose function is regulated by an insulin-sensitive protein kinase or phosphatase.
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PMID:Actions of insulin, epinephrine, and dibutyryl cyclic adenosine 5'-monophosphate on fat cell protein phosphorylations. Cyclic adenosine 5'-monophosphate dependent and independent mechanisms. 16 23

Human chorionic somatomammotropin extracted and purified from placenta at term was proved to have a lipolytic action in the epididymal fat pad of rats. The following mechanism appears to be involved in the lipolytic action of the hormone; human chorionic somatomammotropin activates adenyl cyclase, thereby increasing the concentration of cyclic AMP in the tissue, which, in turn, activates protein kinase to lead to the activation of hormone sensitive lipase.
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PMID:Lipolytic action of human chorionic somatomammotropin. 16 57

A solubilized preparation of cytochrome P-450, obtained by treatment of mitochondria from bovine corpora lutea with phospholipase A, contained all of the necessary components for the cholesterol side chain cleavage activity. The solubilized cytochrome -450 preparation could be isolated essentially free of endogenous cholesterol side chain cleavage activity by various fractionation techniques. A cholesterol side chain cleavage enzyme system was reconstituted using the isolated cytochrome P-450 preparation and purified adrenodoxin and adrenodoxin reductase (components of the enzyme system purified from the adrenal cortex). Protein kinase was partially purified from the cytosol fraction of bovine corpora lutea. It was purified 43-fold and the activity was highly dependent on cyclic adenosine 3:5-monophosphate (cyclic AMP). When ATP and this partially purified cyclic AMP-dependent protein kinase were added to the reconstituted cholesterol side chain cleavage enzyme assay in which cytochrome P-450 was limiting, a stimulation (20 to 74%) of the conversion of cholesterol into pregnenolone was observed. This stimulation was statistically significant with p value less than 0.001. The stimulatory effect of the protein kinase appeared to be dependent on ATP and was not mimicked by bovine serum albumin, indicating that the effect was specific for protein kinase. Protein kinase caused a phosphorylation of the cytochrome P-450 preparation when large amounts of this preparation were used in the assay. It is concluded from these results that the direct activation of the cytochrome P-450 component of the cholesterol side chain cleavage by protein kinase may be one of the ways by which cyclic AMP mediates the effect of luteinizine.
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PMID:Protein kinase stimulation of a reconstituted cholesterol side chain cleavage enzyme system in the bovine corpus luteum. 16

Daily intraperitoneal injection of cadmium chloride (0.25 or 1 mg/kg) to rats for 45 days significantly elevated the endogenous levels of cyclic AMP (cAMP) in hepatic tissue. However, the cAMP binding to hepatic protein kinase was decreased following cadmium administration, as was the kinase activity ratio. Although both doses of cadmium produced slight alterations in the cAMP-independent form of hepatic protein kinase, only the 1.0 mg/kg dose significantly depressed (24%) the activity of the cAMP-dependent enzyme. In contrast to liver, chronic exposure to cadmium significantly reduced the endogenous cAMP levels in kidney cortex. Although treatment with the lower dose (0.25 mg/kg) failed to alter either the cAMP-binding capacity of the renal enzyme or the kinase activity ratio, the higher dose (1 mg/kg) of cadmium did cause a significant increase in both parameters. In addition, cadmium treatment produced a significant decrease in both the cAMP-dependent and the independent forms of protein kinase in kidney cortex. Data suggest that the concentration of cAMP as well as its interaction with cAMP-dependent and independent forms of protein kinase, are altered in both kidney and liver following the prolonged exposure to cadmium.
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PMID:Influence of chronic exposure to cadmium on hepatic and renal cyclic AMP-protein kinase system. 16 69

1. Cell-free lysates of human peripheral blood lymphocytes contained two casein kinase activities and two histone kinase activities, which could be separated by chromatography on DEAE-Sephadex. 2. Neither of the casein kinase activities were stimulated by cyclic AMP. The major activity was eluted from DEAE-Sephadex between 0.4 and 0.45M-KCl, had a molecular weight of approx. 130,000 (sucrose density gradients) and was stimulated by KCl (maximum 150mM). It also formed higher-molecular-weight aggregates when centrifuged in sucrose gradients containing 150mM-KCl. The minor activity was not retained by DEAE-Sephadex, had a molecular weight of approx. 50,000 and was not stimulated by KCl. 3. The major histone kinase activity was stimulated by cyclic AMP and was eluted from the DEAE-Sephadex column between 0.05 and 0.2M-KCl. The other activity was not stimulated by cyclic AMP and was insensitive to the rabbit muscle protein kinase inhibitor. 4. Evidence was obtained suggesting that the lymphocyte casein kinases were located primarily in the nuclei.
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PMID:Multiple protein kinases from human lymphocytes. Identification enzymes phosphorylating exogenous histon and casein. 16 64

Using a homogeneous enzyme from rabbit skeletal muscle, it has been demonstrated that the cyclic adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase reaction is reversible. In addition to the phosphorylated protein substrate, the reverse reaction requires Mg2+, ADP, and cyclic AMP when the holoenzyme is used as the source of enzyme. It is independent of cyclic AMP when the catalytic subunit of the protein kinase is used. The optimum pH for the reverse reaction with 32P-labeled casein as the substrate is 5.7, essentially the same as that for the forward reaction. Among the nucleotide subtrates tested, ADP serves as the best phosphoryl group acceptor. The Km of the enzyme for ADP is 3.3 mM and that for 32P-casein is 1.7 mg/ml. The equilibrium constant at 30 degrees is approximately 0.042 at a magnesium concentration of 10 mM and a pH of 6.9. This result indicates that the free energy of hydrolysis (deltaG0obs) of the phosphorylated protein substrate is relatively high, i.e. approximately -6.5 kcal/mol under these conditions.
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PMID:Reversibility of adenosine 3':5'-monophosphate-dependent protein kinase reactions. 16 60


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