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)

One of the low molecular weight components of myosin, g2, was isolated by alkali treatment of myosin and was chemically modified with a spin label reagent, 4-maleimido-2,2,6,6-tetramethylpiperidinooxyl. The label on g2 showed a rather weakly immobilized ESR spectrum and it was clearly affected by Ca2+; the half-maximal change was at around pCa 4. The spin-labeled g2 was incorporated into myosin by exchange with the intrinsic g2 of myosin in 0.6 M KSCN or 4 M LiC1. The label on g2 became strongly immobilized on association with myosin. Under the conditions used, ESR spectral change due to Ca2+ occurred at two different concentration ranges, which were as low as pCa 8 and at around pCa 4. Phosphorylated g2 was isolated from myosin after the protein kinase [EC 2.1.1.37]-catalyzed phosphorylation of myosin and it was also modified with the maleimide label. Dephosphorylation of the phosphorylated g2 was performed using E. coli alkaline phosphatase [EC 3.1.3.1]. The effects of Ca2+ on the ESR spectra of phosphorylated and dephosphorylated g2 were investigated on the state associated with myosin. A change in the ESR spectrum from strongly immobilized to weakly immobilized states was observed with both g2 chains on the addition of Ca2+. However, the effective concentration ranges of Ca2+ were quite different; around pCa 4 for the phosphorylated g2 and around pCa 8 for the dephosphorylated g2. The results indicate that g2 undergoes a conformational change at physiological levels of Ca2+ sufficient to saturate troponin, but it does not do so after phosphorylation.
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PMID:Ca2+-induced conformational changes of spin-labeled g2 chain bound to myosin and the effect of phosphorylation. 18 78

Cardiac myofibrils were purified from canine myocardium, and the regulatory proteins (troponin + tropomyosin) were extracted and shown to contain endogenous cyclic AMP-dependent protein kinase activity. Other cyclic nucleotide stimulated the protein kinase activity but only at higher concentrations. The enzyme was able to catalyze phosphorylation of conventional substrates such as histones and casein as well as a component of the regulatory protein fraction with a molecular weight of 28,000 daltons. Endogenous phosphorylation required the presence of Mg2+ and was inhibited by Ca2+. A protein kinase inhibitor obtained from skeletal muscle inhibited the cyclicAMP-dependent phosphorylation. Escherichia coli alkaline phosphatase dephosphorylated the endogenous substrates. The level of phosphorylation found is severalfold higher than we have previously reported. A protein kinase, with its close association with the regulatory proteins, seems to be well suited to transmitting the message from the cyclic AMP to the regulatory proteins, a phenomenon that may influence the cardiac contractility via the troponin phosphorylation. The inhibitory effect of troponin on actomyosin might be changed by its state of phosphorylation.
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PMID:Phosphorylation of cardiac regulatory proteins by cyclic AMP-dependent protein kinase. 18 66

A procedure for the purification of cholesterol ester hydrolase from bovine adrenal cortical 105000 x g supernatant is described. Preincubation of a crude enzyme extract with [gamma-32P]ATP followed by purification resulted in the isolation of a phosphorylated preparation of cholesterol ester hydrolase. The phosphorylated cholesterol ester hydrolase appeared to be composed of 4 subunits, each having a molecular weight of 41000 +/- 280, only one of which may be phosphorylated. Preincubation of the crude enzyme preparation with [alpha-32P]ATP followed by purification did not produce a phosphorylated preparation of cholesterol ester hydrolase. Cyclic-AMP-dependent protein kinase, cyclic AMP, ATP and magnesium ions were required for activation of purified cholesterol ester hydrolase in vitro and the time course of activation closely paralleled the time course of phosphorylation of the enzyme. The addition of ATP, cyclic AMP and magnesium ions to the bovine adrenal cortical 105000 x g supernatant produced a 2.5-fold stimulation in cholesterol ester hydrolase activity. This stimulation was abolished if protein kinase inhibitor was added prior to the addition of ATP cyclic AMP and magensium ions. The addition of magnesium ions or calcium ions to a crude preparation of cholesterol ester hydrolase was found to inhibit activity; however the same additions made to a purified preparation of cholesterol ester hydrolase were not inhibitory. The decrease in cholesterol ester hydrolase activity on incubation with magnesium ion was accompanied by a loss of 32P radioactivity from the protein. Preincubation of a crude preparation of cholesterol ester hydrolase with alkaline phosphatase resulted in a deactivation of cholesterol ester hydrolase. It is suggested that bovine adrenal cortex cholesterol ester hydrolase is activated by a phosphorylation catalysed by a cyclic-AMP-dependent protein kinase. Deactivation of cholesterol ester hydrolase is accomplished by dephosphorylation catalysed by a phosphoprotein phosphatase, dependent on magnesium or calcium ions.
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PMID:Purification and control of bovine adrenal cortical cholesterol ester hydrolase and evidence for the activation of the enzyme by a phosphorylation. 18 99

Myocardial acidic non-histone nuclear proteins (NHPs) contain endogenous protein kinase activity. Phosphocellulose chromatography of purified NHPs identifies nine separate peaks of protein kinases which can phosphorylate both endogenous and exogenous substrates to a variable degree; endogenous NHPs are the best substrates. Cyclic AMP-stimulated protein kinase induced phosphorylation of endogenous and exogenous substrates; the extent of this stimulation varied according to the protein kinase fraction and substrate used. Cyclic AMP also enhanced NHP-induced stimulation of RNA polymerase activity. This enhancement was dependent on protein kinase-induced phosphorylation of NHPs since it was prevented by alkaline phosphatase pretreatment. It is concluded that nuclear protein kinases regulate myocardial RNA synthesis by enhancing phosphorylation of NHPs and that this regulation is under cyclic AMP control.
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PMID:Adenosine 3',5'-monophosphate-dependent protein kinases of myocardial non-histone nuclear proteins. 19 45

The catalytic subunit of rabbit skeletal muscle cyclic AMP-dependent protein kinase I can catalyze self-phosphorylation. The autophosphorylation reaction uses ATP as the phosphoryl donor, requires Mg2+, and is inhibited by polyarginine. Prior treatment of the catalytic subunit with Escherichia coli alkaline phosphatase in the presence of bovine serum albumin greatly enhances the autophosphorylation of the subunit. The protein-bound phosphate is stable in acid but labile in base. Incubation of the 32P-labeled phosphoenzyme with histones led neither to the phosphorylation of histones nor to a loss of radioactivity from the phosphoenzyme. The results suggest that the phosphoenzyme does not represent an intermediate of the phosphotransferase reaction.
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PMID:Autophosphorylation of rabbit skeletal muscle cyclic AMP-dependent protein kinase I catalytic subunit. 21 18

Rat adipose-tissue glycerol phosphate acyltransferase can be inactivated in a phosphorylation reaction catalysed by cyclic AMP-dependent protein kinase and reactivated by treatment with alkaline phosphatase. These results suggest that phosphorylation of glycerol phosphate acyltransferase may be involved in the hormonal control of esterification.
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PMID:Rat adipose-tissue glycerol phosphate acyltransferase can be inactivated by cyclic AMP-dependent protein kinase. 21 67

Phosphorylation of rat and rabbit troponin from normal skeletal muscles and from skeletal muscles of animals under avitaminosis, denervation and hypokinesia was studied. Phosphorylation was carried out by cAMP-dependent protein kinase with [gamma-33P] as substrate. The incorporation of labelled phosphorus into troponin T of the damaged muscles was decreased as compared to normal. After preliminary dephosphorylation of troponin by alkaline phosphatase immobilized on Sepharose 4B, the ability of damaged muscle troponin for subsequent phosphorylation was also decreased as compared to the control. It may be thus assumed that there exist conformational changes of troponin under muscular system pathologies.
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PMID:[Peculiarities of phosphorylation of skeletal muscle troponin under some forms muscle pathologies]. 21 14

Properties of the helix-destabilizing protein from Lilium meiotic cells, 'R-protein', have been examined after treating it either with alkaline phosphatase or with two types of protein kinase. Dephosphorylation with the phosphatase increases binding capacity for single-strand DNA, but abolishes specificity of binding. Dephosphorylated R-protein binds equally to single and double-strand DNA. The capacity to facilitate denaturation or renaturation of DNA is also abolished by the treatment, but cooperativity characteristics are unaffected. The consequences of protein kinase treatment of native or dephosphorylated R-protein depend upon the origin of the kinase. Heterologous cyclic-AMP-dependent protein kinase cannot reverse the effects of dephosphorylation. However, it abolishes the binding affinity of either native or dephosphorylated R-protein for DNA. A protein kinase isolated from meiotic cells has no effect on the native protein, but it does restore all native properties tested to the dephosphorylated form after phosphorylating approximately two residues/molecule of protein.
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PMID:The effect of dephosphorylation on the properties of a helix-destabilizing protein from meiotic cells and its partial reversal by a protein kinase. 22 79

Protein kinase activity (ATP:protein phosphotransferase, EC 2.7.1.37) has been found associated with the D2 hybrid protein, a highly purified protein of 107,000 daltons specified by the adenovirus-simian virus 40 (SV40) hybrid Ad2(+)D2, which has many properties associated with authentic SV40 T antigen [Tjian, R. & Robbins, A. (1979) Proc. Natl. Acad. Sci. USA 76, 610-614]. We have now examined some of the biochemical characteristics of the reaction products. Acceptors for the terminal phosphoryl group of [gamma-(32)P]ATP are the purified protein itself and at least four proteins extracted from nuclei of uninfected cells. Purified histones do not serve as substrate for the enzyme. Phosphorylation is markedly reduced by heating the D2 hybrid protein to 50 degrees C for 30 min. The products of phosphorylation are stable to treatment with ethanol/ether, DNase, and RNase, but completely degraded by digestion with Pronase, demonstrating their protein nature. The phosphate bonds are liable to hot alkali and sensitive to digestion with alkaline phosphatase but stable to treatment with hot acid or hydroxylamine. These results provide evidence that (32)P is incorporated into O-phosphoserine or O-phosphothreonine residues of acceptor proteins, indicating that the enzymatic activity is characteristic for protein kinase, and that cell-specified nuclear proteins other than histones may serve as substrates for the enzyme.
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PMID:Protein kinase activity associated with the D2 hybrid protein related to simian virus 40 T antigen: some characteristics of the reaction products. 22 74

Yeast DNA-dependent RNA polymerases I, II, and III are phosphorylated in vivo. Yeast cells were grown continuously in 32Pi and the RNA polymerases were isolated by a new procedure which allows the simultaneous purification of these enzymes from small quantities (35 to 60 g) of cells. Each of the RNA polymerases was phosphorylated. The following phosphorylated polymerase polypeptides were identified: polymerase I subunits of 185,000, 44,000, 36,000, 24,000, and 20,000 daltons; a polymerase II subunit of 24,000 daltons; and polymerase III subunits of 24,000 and 20,000 daltons. The incorporated 32P was acid-stable but base-labile. Phosphoserine and phosphothreonine were identified after partial acid hydrolysis of purified [32P]polymerase I. A yeast protein kinase that co-purifies with polymerase I during part of the isolation procedure was partially purified and characterized. This protein kinase phosphorylates the subunits of the purified polymerases that are phosphorylated in vivo and, in addition, a polymerase I subunit of 48,000 daltons and a polymerase II subunit of 33,500 daltons. Phosphorylation of the purified enzymes with this protein kinase had no substantial effect on polymerase activity in simple assays using native yeast DNA as a template. Preincubation of purified polymerase I with acid or alkaline phosphatase also had no detectable effect on polymerase activity.
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PMID:Phosphorylation of yeast DNA-dependent RNA polymerases in vivo and in vitro. Isolation of enzymes and identification of phosphorylated subunits. 32 61


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