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)

1. Various proteins isolated from bovine tracheal smooth muscle were examined as phosphate acceptor substrates for a cyclic AMP-dependent protein kinase isolated from the same tissue. A fraction prepared in a manner similar to that of skeletal muscle troponin was the best substrate of the presumptive contractile proteins isolate. Actomyosin and tropomyosin were relatively poor substrates. 2. An assay was developed for the rapid detection in a large number of samples of the muscle specific substrate for the protein kinase on which we reported previously. 3. Using this assay, the muscle specific substrate found in bovine tracheal smooth muscle was partially purified resulting in a preparation which when resolved by polyacrylamide gel electrophoresis showed a single peak of 32P incorporated, and which could be further characterized. 4. Our findings suggest that the substrate contains a protein subunit of molecular weight 19 000, which can be phosphorylated at serine and threonine residues, in the presence of cyclic AMP and protein kinase. The phosphate is in a covalent ester linkage with these residues. 5. A phosphoprotein phosphatase was isolated from the bovine tracheal smooth muscle. 6. Bovine tracheal smooth muscle contains cyclic AMP dependent protein kinase and phosphoprotein phospahatase activity as well as the muscle specific substrate, suggesting that these elements may be part of a mechanism which regulates smooth muscle tone.
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PMID:Cyclic AMP-stimulated phosphorylation of bovine tracheal smooth muscle contractile and non-contractile proteins. 18 31

Previous reports from this laboratory and others have established that both the rabbit and human erythrocyte membranes contain multiple protein kinase and phosphate acceptor activities. We now report that these membranes also contain phosphoryl acceptor sites for the soluble cyclic AMP-dependent and -independent protein kinases from rabbit erythrocytes. The rabbit erythrocyte membrane, which does not contain a cyclic AMP-dependent protein kinase, has at least four polypeptides (Bands 2.1, 2.3, 4.5, and 4.8) which are phosphorylated in the presence of the soluble cyclic AMP-dependent protein kinases I, IIa, and IIb isolated from rabbit erythrocyte lysates. The resulting phosphoprotein profile is very similar to that obtained for the cyclic AMP-mediated autophosphorylation of human erythrocyte membranes. The activities of the soluble cyclic AMP-dependent protein kinases toward the membranes have been studied at several pH values. Although the substrate specificity of the three kinases is similar, polypeptide 2.3 appears to be phosphorylated to a greater extent by kinase IIa than by I or IIb. This occurs at all pH values studied. Also apparent is that the pH profile for membrane phosphorylation is different from that of histone phosphorylation. The phosphorylation of membrane proteins can also be catalyzed by the soluble erythrocyte casein kinases. These enzymes are not regulated by cyclic nucleotides and can use either ATP or GTP as their phosphoryl donor. Polypeptides 2.1, 2.9, 4.1, 4.5, 4.8, and 5 of both human and rabbit erythrocyte membranes are phosphorylated in the presence of GTP and the casein kinases. This reaction is optimal at pH 7.5. Experiments were performed to determine whether the phosphorylation of the membranes by the soluble and membrane-bound kinases is additive or exclusive. Our results indicate that after maximal autophosphorylation of the erythrocyte membranes, phosphoryl acceptor sites are available to the soluble cyclic AMP-dependent and -independent protein kinases. Furthermore, after maximal phosphorylation of the membranes with one type of soluble kinase, further 32P incorporation can occur as a result of exposure to the other type of soluble kinase.
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PMID:Phosphorylation of rabbit and human erythrocyte membranes by soluble adenosine 3':5'-monophosphate-dependent and -independent protein kinases. 18 4

The reversible deactivation of chicken adipose tissue hormone-sensitive lipase alpha(previously activated with Mg2+ ATP and adenosine 3':5'-monophosphate) required Mg2+ and was inhibited by phosphate. These results are consistent with the assumption that deactivation of the protein kinase-activated enzyme is catalyzed by a lipase phosphatase. Cholesterol ester is catalyzed by a lipase phosphatase. Cholesterol ester hydrolase similarly was activated and reversibly deactivated. The activity of endogenous lipase phosphatase in pH 5.2 precipitate fractions was reduced, and in some cases eliminated, by incubation at 50 degrees for 20 min in buffer containing 20% glycerol. Heating at 50 degrees greatly increased the apparent percentage activation of triglyceride and cholesterol ester hydrolases but this was due to a selective decrease in basal (nonactivated) hydrolase activities. Essentially all endogenous lipase phosphatase could be removed by treatment of the pH 5.2 precipitate fraction with ATP-Sepharose affinity gel. The addition of a partially purified preparation of rat liver phosphorylase phosphatase deactivated triglyceride and cholesterol ester hydrolases. The deactivation process was concentration, 5 mM) and was inhibited by 5 mM phosphate and by phosphorylase alpha. Reversible deactivation of hormone-sensitive lipase alpha was also observed with crude prepa- and by phosphorylase alpha. Reversible deactivation of hormone-sensitive lipas alpha was also observed with crude preparations of phosphoprotein phosphatases from rat and turkey hearts, and from rat epididymal fat pads. Thus, hormone-sensitive lipase is deactivated by a variety of phosphoprotein phosphatases from different tissues and different species, implying a low degree of specificity for the deactivating system.
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PMID:Role of phosphoprotein phosphatases in reversible deactivation of chicken adipose tissue hormone-sensitive lipase. 19 Feb 35

Ripe Xenopus oocytes in first meiotic prophase when incubated with progesterone in vitro progress synchronously in 3 to 5 h without interphase to second meiotic metaphase where they remain until fertilization or activation. Using highly purified preparations of regulatory and catalytic subunits of adenosine 3':5'-monophosphate-dependent protein kinase from muscle, this progesterone-stimulated cell division sequence was found to be inhibited by microinjection of the catalytic subunit and induced directly in the absence of progesterone after microinjection of regulatory subunit. Dose-response curves revealed that half-maximal effects of regulatory and catalytic subunits occurred at an internal concentration of approximately 0.1 muM. These results indicate that the catalytic subunit is necessary and sufficient to block progesterone-stimulated meiotic cell division. Other experiments revealed that the catalytic subunit was inhibitory only during the first hour after progesterone exposure, suggesting that initial steps in meiotic cell division are affected. Control experiments demonstrate that the muscle cAMP-dependent protein kinase subunits may interact with the endogenous oocyte protein kinase. The results support a model in which meiotic cell division is regulated by a phosphoprotein subject to control by cAMP-dependent protein kinase.
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PMID:Progesterone-stimulated meiotic cell division in Xenopus oocytes. Induction by regulatory subunit and inhibition by catalytic subunit of adenosine 3':5'-monophosphate-dependent protein kinase. 19 Feb 38

A phosphoprotein phosphatase that catalyzes the dephosphorylation of cyclic adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase from bovine cardiac muscle has been purified to homogeneity by a modification of the procedure of Brandt et al. (Brandt, H., Capulong, Z.L., and Lee, E. Y. C. (1975) J. Biol. Chem. 250, 8038-8044). Treatment of the enzyme preparation with ethanol during the early stages of purification results in activation concomitant with reduction in molecular weight to 30,000. The purified activated enzyme has a Km for phospho-protein kinase in the presence or absence of 1.2 mM Mn2+ of 5 and 22 micronM, respectively. Phosphatase activity on phospho-protein kinase but not on other phosphoprotein substrates was cAMP-dependent. This selective activation by cAMP reflects the preference of the phosphatase for the free, phosphorylated cAMP-binding protein rather than the phosphoholoenzyme.
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PMID:Purification of phosphoprotein phosphatase from bovine cardiac muscle that catalyzes dephosphorylation of cyclic AMP-binding protein component of protein kinase. 19 23

Similar time courses were obtained for decreases in the rate of calcium transport by cardiac sarcoplasmic reticulum vesicles previously phosphorylated by cAMP-dependent protein kinase and dephosphorylation of the 22,000-dalton phosphoprotein in these membranes. Dephosphorylation of the 22,000-dalton phosphoprotein can be attributed to a phosphoprotein phosphatase in the sarcoplasmic reticular membranes. This membrane-bound phosphoprotein phosphatase may play a role in the reversal of the relaxation-promoting effect of catecholamines on the heart.
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PMID:Phosphoprotein phosphatase-catalyzed dephosphorylation of the 22,000-dalton phosphoprotein of cardiac sarcoplasmic reticulum. 20 87

Filamin is a high molecular weight protein that binds to actin filaments in cells. It is found in large amounts in several different cells and tissues, including smooth muscle, fibroblasts, platelets, and macrophages. It is immunologically related to the previously described macrophage high molecular weight actin-binding protein but clearly different from erythrocyte spectrin. Filamin is a phosphoprotein; it is phosphorylated in vivo in intact tissues and cells. It can be phosphorylated in vitro with endogenous kinases; cyclic AMP stimulates this phosohorylation. Furthermore, the purified protein can be phosphorylated by purified cyclic AMP-dependent protein kinase. In smooth muscle homogenates, the stimulation of filamin phosphorylation by cyclic AMP is specific. Cyclic GMP and Ca2+ do not increase its phosphorylation, although they do stimulate phosphorylation of other proteins.
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PMID:Cyclic AMP-dependent phosphorylation of the actin-binding protein filamin. 20 86

Inhibitor-1 from rabbit skeletal muscle was phosphorylated by protein kinase dependent on adenosine 3' :5'-monophosphate (cyclic AMP), but not by phosphorylase kinase or by glycogen synthetase kinase-2. Protein phosphatase-III, isolated and stored in the presence of manganese ions to keep it stable, was in a form which catalysed a rapid dephosphorylation and inactivation of inhibitor-1. The kinetic constants for the dephosphorylation of inhibitor-1 [Km = 0.7 micron, V(rel) = 40] were comparable to those for the dephosphorylation of phosphorylase kinase [Km =1.1 micron, V (rel) = 62] and phosphorylase [Km = 5.0 micron, V (rel) = 100]. The dephosphorylation of inhibitor -1 was inhibited by inhibitor-2, indicating that it was catalysed by protein phosphatase-III, and not by another enzyme that might be contaminating the preparation. When protein phosphatase-III was diluted into buffers containing excess EDTA, it lost activity initially, but after 90 min, the activity reached a plateau that remained stable for at least 20h. The initial loss in activity varied with the substrate that was tested; it was 20-30% with phosphorylase a, 50-60% with phosphorylase kinase and greater than or equal to 95% with inhibitor-1. This form of protein phosphatase-III was inhibited by inhibitor-1 in a noncompetitive manner, and the Ki for inhibitor-1 was 1.6 +/- 0.3 nM. The phosphorylase phosphatase, phosphorylase kinase phosphatase and glycogen synthetase phosphatase activities of protein phosphatase-III were inhibited in an identical manner by inhibitor-1. This result emphasizes the potential importance of inhibitor-1 in the regulation of glycogen metabolism, since it can influence the state of phosphorylation of three different enzymes. The formation of the inactive complex between inhibitor-1 and protein phosphatase-III was reversed by incubation with trypsin (which destroyed inhibitor-1, but not protein phosphatase-III) or by dilution of the inactive complex. Kinetic studies, using the form of protein phosphatase-III which dephosphorylated inhibitor-1 very rapidly, demonstrated three unusual features of the system: (a) inhibitor-1 was still as powerful and inhibitor of the dephosphorylation of phosphorylase a and phosphorylase kinase a even under conditions where it was being rapidly dephosphorylated; (b) inhibitor-1 was not an inhibitor of its own dephosphorylation; (c) phosphorylase a did not effect the rate of dephosphorylation of inhibitor-1 even when it was present in a 50-fold molar excess over inhibitor-1. The result of these three properties is that inhibitor-1 is preferentially dephosphorylated by protein phosphatase-III even in the presence of a large excess of other phosphoprotein substrates. Inhibitor-1 was also dephosphorylated by protein phosphatase-II. The kinetic constants for the dephosphorylation of inhibitor-1 [Km = 2.8 micron, V (rel) = 200] and the alpha-subunit of phosphorylase kinase [Km = 3.7 micron, V (rel) = 100]were comparable...
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PMID:The regulation of glycogen metabolism. Phosphorylation of inhibitor-1 from rabbit skeletal muscle, and its interaction with protein phosphatases-III and -II. 20 45

The avian sarcoma virus (ASV) protein responsible for cellular transformation in vitro and sarcomagenesis in animals was studied structurally with special reference to the sites of phosphorylation on the polypeptide. The product of the ASV src gene, pp60src, is a phosphoprotein of 60,000 daltons. We found that pp60src contained two major sites of phosphorylation, one involving phosphoserine and the other involving phosphothreonine and possible addtional minor sites of phosphorylation. By using N-formyl[35S]methionyl-tRNAf as a radiolabeled precursor in the cell-free synthesis of the src protein in conjunction with partial proteolysis mapping, we determined that the major phosphoserine residue was located on the amino-terminal two-thirds of the molecule and that the phosphothreonine was located on the carboxy-terminal third. We further determined that the phosphorylation of pp60src in cell extracts involved at least two protein kinases, the one that phosphorylated the major serine site being cyclic AMP dependent and the other, acting on the threonine residue, being a cyclic nucleotide-independnet phosphotransferase. Finally, analysis of the pp60src isolated from cells infected with a temperature-sensitive src gene mutant of ASV revealed that phosphorylation of the major threonine residue was severely reduced when infected cells were grown at the nonpermissive temperature, whereas a phosphorylation pattern characteristic of the wild-type pp60src was observed at the permissive temperature. As pp60src has an associated protein kinase activity, the possible involvement of phosphorylation-dephosphorylation reactions in the functional regulation of ASV transforming protein enzymatic activity is discussed.
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PMID:Structural analysis of the avian sarcoma virus transforming protein: sites of phosphorylation. 21 58

Genetic analyses have defined a single gene (src) as that portion of the avian sarcoma virus (ASV) genome which encodes the protein directly responsible for ASV-induced neoplastic transformation. We have recently identified the polypeptide product of the src gene of the Schmidt-Ruppin (SR) strain of ASV, a 60,000-dalton phosphoprotein designated pp60(src), and have further determined that pp60(src) acts as a protein kinase. Essential to the identification and characterization of the pp60(src) protein of SR-ASV was the use of serum (TBR serum) from rabbits bearing SR-ASV-induced tumors. TBR serum was, however, strain specific, recognizing pp60(src) from SR-ASV-transformed cells only. We report here that sera from marmosets bearing tumors induced by the Bryan or SR strains of ASV (TBM sera) contain antibody which precipitates the transforming gene product from cells transformed by the SR, Bryan, Prague, or Bratislava strains of ASV. In contrast, rabbits bearing tumors induced by either the Bratislava or Bryan strains of ASV, or hamsters with SR-ASV-induced tumors did not produce antibody to pp60(src) from any strain of ASV. The 60,000-dalton polypeptides immunoprecipitated with TBM serum from cells transformed by each of the above virus strains are phosphoproteins. One-dimensional peptide mapping by limited proteolysis revealed that the pp60(src) proteins are structurally very similar, but not identical. Furthermore, all of the viral pp60(src) proteins have an associated phosphotransferase activity. In addition to detecting the viral src proteins, TBM serum was able to immunoprecipitate an antigenically related protein from normal uninfected avian cells.
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PMID:Detection of the viral sarcoma gene product in cells infected with various strains of avian sarcoma virus and of a related protein in uninfected chicken cells. 22 73


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