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)

When highly purified myelin from rat sciatic nerve was incubated with [gamma-32P]ATP, protein components of the membrane were phosphorylated indicating the presence of both the substrate (receptor protein) and an endogenous kinase in the membrane. Polyacrylamide gel electrophoresis of the phosphorylated membrane proteins followed by scintillation counting of gel slices and autoradiography showed that the polypeptides of molecular weights 28000, 23000 and 19000 were phosphorylated, and 32P from [gamma-32P]ATP having been incorporated into serine residues of the substrate proteins. Phosphorylation of purified myelin was Mg2+-dependent, was optimal at pH 6.5 and was not stimulated by adenosine 3',5'-monophosphate. We found that proteins other than those in myelin, such as phosvitin, casein, protamine and histones, can also act as a substrate for the membrane associated kinase. Muscle protein kinase inhibitor had no effect on the endogenous phosphorylation of myelin proteins or on the phosphorylation of phosvitin by peripheral nerve myelin protein kinase. However, the phosphorylation of histone by peripheral nerve myelin protein kinase was inhibited by the protein kinase inhibitor. After washing the membrane with 150 mM KCl the protein kinase that utilizes histone as substrate was found in the supernatant. In contrast, the endogenous phosphorylation of membrane proteins or the phosphorylation of phosvitin by the membrane associated kinase was not affected by washing. From these findings we conclude that at least two protein kinase systems exist in purified peripheral nerve myelin. One system is not inhibited by muscle kinase inhibitor, is tightly bound to the membrane and utilizes as its receptor proteins either exogenous phosvitin or endogenous membrane proteins. The second system is inhibited by muscle kinase inhibitor, is removable from the membrane and utilizes histones as its receptor proteins.
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PMID:Protein kinases associated with peripheral nerve myelin. 1. Phosphorylation of endogenous myelin proteins and exogenous substrates. 0 57

Protein kinase activities were identified in a soluble and a particulate fraction from the A. coronaria of cattle. For both protein kinase activities Mg++ is essential. Protamine was used as a substrate of the protein kinase activity of the soluble fraction. The pH optimum of the protein kinase activity of the soluble fraction is around 6.5. The Km-value of the protein kinase for ATP is 1.9 +/- 0.4 - 10(-5) M. cAMP stimulates the protein kinase activity more effectively than cGMP. Ca++ cannot replace Mg++; monovalent cations (Na+ and K+) show no influence. The protein kinase activity of the fraction was determined via endogenous phosphorylation. By means of the cAMP-dependent particulate protein kinase 72 to 80 percent of the serine residues are phosphorylated. The pH optimum of the protein kinase activity of the particulate fraction lies around 7.0. The Km-value of the enzyme for ATP is 6.6 +/- 0.8 - 10(-5) M. cGMP stimulates the protein kinase of the particulate fraction better than cAMP. For the protein kinase activity of this fraction Ca++ replaces Mg++ in the endogenous phosphorylation but not in the exogenous phosphorylation (protamine). In the presence of Mg++ and in the additional presence of Na+ or K+, the protein kinase activity is suppressed in the endogenous phosphorylation whereas it is stimulated in the exogenous phosphorylation.
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PMID:[Demonstration of protein kinase activities in the coronary artery of cattle]. 1 87

A phosphoprotein kinase (ATP : protein phosphotransferase, EC 2.7.1.37) from calf thymus nuclei was purified by DEAE-cellulose chromatography, hydroxyapatite, and Sepharose 6B gel filtration. The enzyme is a cyclic AMP-independent protein kinase by the following criteria: (a) the protein kinase did not bind cyclic AMP; (b) no inhibition of activity was obtained with the heat-stable protein kinase inhibitor from rabbit skeletal muscle; (c) the regulatory subunit of cyclic AMP-dependent protein kinase had no effect on activity; and (d) no inhibition was obtained with antibody to cyclic AMP-dependent protein kinase. The nuclear cyclic AMP-independent protein kinase readily phosphorylated protamine on serine and to a lesser extent on threonine. Homologous nucleoplasmic RNA polymerase (EC 2.7.7.6) is a better substrate than arginine-rich histone, phosvitin or casein. Physical characteristics of the enzyme are described.
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PMID:Purification and properties of a cyclic AMP-independent protein kinase from calf thymus nuclei. 2 35

The interaction between pyridoxal 5'-phosphate and the convertible serine of glycogen phosphorylase has been investigated by using: specific interconverting enzymes, phosphorylase kinase and phosphorylase phosphatase; effectors, glucose and glucose 6-phosphate; and a protein kinase and trypsin. Both phosphorylase kinase and phosphorylase phosphatase utilized the native protein while having little influence on the apoprotein. Removal of a peptide containing the critical serine residue gave phosphorylase b' from which the pyridoxal 5'-phosphate in phosphorylase has an important effect on enzymic interconversion.
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PMID:Pyridoxal phosphate-dependent conformational states of glycogen phosphorylase as probed by interconverting enzymes. 16 24

Two tryptic phosphopeptides containing the sites on the alpha and beta subunits of phosphorylase kinase which are phosphorylated by protein kinase, dependent on adenosine 3':5'-monophosphate (cyclic AMP), have been isolated and their amino acid sequences have been determined. 32P-labelled phosphorylase kinase, containing 1.9 mol phosphate per mol enzyme, was digested with an equimolar quantity of trypsin for 2.5 min at pH 7.0, 20 degrees C. This treatment released nearly all the 32P radioactivity associated with the beta subunit as trichloroacetic-acid-soluble material. Only a small proportion of the 32P radioactivity associated with the alpha subunit was solubilised, the remainder being removed in the trichloroacetic acid pellet. The beta-subunit tryptic phosphopeptide was completely resolved from traces of the alpha-subunit phosphopeptide by gel filtration on Sephadex G-25. Further purification by peptide mapping separated the phosphopeptide into four components, each derived from the same nine-amino-acid segment of the betachain, which was found to possess the sequence: Gln-Ser-Gly-Ser(P)-Val-Ile-Tyr-Pro-Leu-Lys. The four components were produced by the partial cyclisation of the N-terminal glutaminyl residue, and by the presence of two alleles for the beta subunit in the rabbit population, which led to a valine-isoleucine ambiguity. The alpha-subunit phosphopeptide was liberated from the trichloroacetic acid pellet by redigestion with trypsin. It was the largest component in the digest which remained soluble in 5% trichloroacetic acid, and obtained in a highly purified form by a single filtration on Sephadex G-50. The peptide comprised 39 amino acids of which nine were serine and three were threonine residues. Only one residue, the serine at position three from the amino terminus, was phosphorylated. The amino-terminal sequence of the peptide was shown to be: Arg-Leu-Ser(P)-Ile-Ser-Thr-Glu-Ser-Glx-Pro-Asx-Gly. The sequences confirm the stoichiometry of the reaction and the absolute specificity of cyclic-AMP-dependent protein kinase for just two of the 200 serine residues in the enzyme. These results and an inspection of the rate of phosphorylation of a number of skeletal muscle proteins, including each enzyme of the glycolytic pathway, lead to the conclusion that cyclic-AMP-dependent protein kinase is an extremely specific enzyme. The molecular basis of this specificity is discussed.
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PMID:The hormonal control of activity of skeletal muscle phosphorylase kinase. Amino-acid sequences at the two sites of action of adenosine-3':5'-monophosphate-dependent protein kinase. 16 50

Non-histone chromosomal proteins are phosphorylated and dephosphorylated within the intact nucleus by two independent sets of reactions, a protein kinase reaction which transfers the terminal phosphate group of a variety of nucleoside and deoxynucleoside triphosphates to serine and threonine residues in the proteins, and a phosphatase reaction which cleaves these phosphoserine and phosphothreonine bonds and releases inorganic phosphate. Several lines of evidence are consistent with the hypothesis that the phosphorylation and dephosphorylation of these proteins is involved in gene control mechanisms, including the findings that phosphorylated non-histone proteins are highly heterogeneous and their phosphorylation patterns are tissue specific, changes in their phosphorylation correlate with changes in chromatin structure and gene acticity, addition of phosphorylated non-histone proteins increases RNA synthesis in vitro. and phosphorylated non-histone proteins bind specifically to DNA. Cyclic AMP has both stimulatory and inhibitory properties on non-histone protein phosphorylation, depending on the enzyme fraction and substrate employed A specific protein component whose phosphorylation is inhibited by cyclic AMP has been found to be associated with RNA polymerase. The cyclic AMP-induced decrease in the phosphorylation of this protein correlates with an enhancement of RNA synthesis in vitro. These results suggest that both phosphorylation and dephosphorylation of chromatin-associated proteins may be involved in the control of gene readout.
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PMID:Phosphorylation of non-histone proteins in the regulation of chromosome structure and function. 16 80

An adenosine 3':5'-monophosphate-dependent protein kinase II (ATP:protein phosphotransferase, EC 2.7.1.37) was partially purified from the cytosol fraction of an exponentially growing culture of Tetrahymena pyriformis. Protein kinase II represented approximately 90% of the cytosolic protein kinase activity. The enzyme had a high degree of substrate specificity for calf thymus and Tetrahymena histones as compared to casein, protamine and phosvitin. The enzyme incorporated the terminal phosphate of ATP into serine and threonine residues of all the histone fractions. The apparent Km of the enzyme for adenosine 3':5'-monophosphate (cyclic AMP) was 1-10-minus 8 M. Protein kinase II was also activated by other cyclic nucleotides with apparent Km values in the range 2.k-10-minus 6 M. Ther specific activity of the cyclic AMP-dependent protein kinase of Tetrahymena decreases markedly from initial high values during the transition from the lag to early log phase of growth. This is followed by a shrp increase in the activity of the enzyme as the log phase of growth progresses. The specific activity of the enzyme increases rapidly during the heat-induced synchronization of Tetrahymena cells. The capacity for rapid phosphorylation of multiple classed of organelle-specific phosphoproteins and the level of cyclic AMP were maximal in Tetrahymena during the earliest phase of growth. These results demonstrate that the cell cycle of Tetrahymena may be coordinated by marked variations in the level of cyclic AMP which in turn regulate the cyclic AMP-dependent protein kinase.
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PMID:Changes in cyclic AMP-dependent protein dinase activity in Tetrahymena pyriformis during the growth cycle. 16 17

Plasma membranes have been prepared from porcine thyroid glands using sucrose gradients. The fractions having a density in sucrose of 1.18 g/ml mainly contained plasma membranes and were moderately contaminated with other subcellular components as shown by marker enzyme data. Purified plasma membranes incubated in the presence of [32-P]gamma ATP incorporated 32-P. Kinetics of incorporation of 32-P into endogenous substrates studied in various buffers and with increasing ATP concentration suggest a phosphodephosphorylating system related to cAMP-dependent protein kinase and phosphoprotein phosphatase activities. The two enzymatic activities associated with plasma membranes have been demonstrated using exogenous substrates. cAMP increases and fluoride ions decrease the extent of membrane phosphorylation. The specific activity of protein kinase was 10-12 times higher than in the initial homogenate and was only slightly enhanced in the presence of 0.5% Nonidet as compared to microsomal fraction. cAMP binding to membrane proteins was 3 times higher than to the other particulate fractions. TSH present in the incubating medium or added after 5 min of 32-P labelling induced a rapid stimulation of endogenous phosphorylation followed by a rapid decrease. Phosphorylated membrane substrates were analyzed: high voltage paper electrophoresis after partial hydrolysis indicated that [32-P]phosphate is incorporated into serine and threonine residues as o-phosphate derivatives. SDS-polyacrylamide gel electrophoresis showed several 32--labelled fractions. When enhanced by cAMP, no specific phosphorylation of protein components was observed.
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PMID:Phosphorylation of purified thyroid plasma membranes incubated with [32-P]ATP. 16 13

Heat-denatured chicken egg white lysozyme and the reduced carboxymethylated maleylated derivative of this protein were found to serve as substrates for rabbit skeletal muscle cyclic AMP-dependent protein kinase. The native form of the protein was not a substrate. Two phosphoryl groups per mole of lysozyme were incorporated in the reaction. It was determined that the phosphoryl moieties were bound to serine 24 and serine 50 in the modified protein. Serine 24 was phosphorylated approximately 3 times as fast as serine 50. Reduced carboxymethylated maleylated derivatives of bovine serum albumin, phosphorylase b, and creatine kinase also served as substrates for the protein kinase whereas their native forms did not. The reduced carboxymethylated maleylated derivative of the inhibitory subunit of troponin was a poorer substrate than the native form of the protein. Maleylated histones F1 and F2b were also poorer substrates than the nonderivatized forms. The significance of these experiments with reference to the specificity of cyclic AMP-dependent protein kinase is discussed.
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PMID:Effect of denaturation on the susceptibility of proteins to enzymic phosphorylation. 16 38

A manyfold increase in phosphorylation of cardiac sarcoplasmic reticulum (SR) was seen when SR was incubated in the presence of a bovine cardiac cyclic AMP-dependent protein kinase and cyclic AMP. This phosphoprotein had stability characteristics of a phosphoester in which the phosphate is incorporated largely into serine, and its formation did not required calcium ions, unlike the formation of acyl phosphoprotein intermediate of calcium-transport ATPase which is present within the same membrane. When examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein kinase-catalyzed phosphorylation occurred at a 22,000-dalton component of the cardiac sarcoplasmic reticulum. This 22,000-dalton protein has been named "phospholamban" (lambda alpha mu beta alpha nu epsilon iota nu = to receive), based on its ability to receive phosphate from ATP. Phosphorylation of phospholamban by cyclic AMP-dependent protein kinase was associated with the stimulation of calcium transport by the cardiac sarcoplasmic reticulum. This stimulation was accompanied by an increase in the calcium-activated ATPase activity, indicating that the overall rate of calcium transport rather than its efficiency is enhanced by protein kinase. The 22,000-dalton phopholamban was susceptible to trypsin. Brief digestion with trypsin in the presence of 1 M sucrose prevented subsequent phosphorylation of phospholamban, while leaving the calcium pump apparently intact. Incubation of trypsin-treated sarcoplasmic reticulum with cyclic AMP-depentent protein kinase did not result in the stimulation of calcium transport. These results may suggest that phospholamban is a modulator of the calcium pump of the cardiac sarcoplasmic reticulum.
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PMID:Regulation of calcium transport in cardiac sarcoplasmic reticulum by cyclic AMP-dependent protein kinase. 17 97


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