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)

Tyrosine hydroxylase [tyrosine monooxygenase, L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] was highly purified from rat caudate nuclei. When the pure hydroxylase was phosphorylated by incubation with cyclic AMP-dependent protein kinase and [32P]ATP, 32P and tyrosine hydroxylase activity were detected after polyacrylamide gel electrophoresis in a single protein band. After sodium dodecyl sulfate gel electrophoresis, 32P was detected only in a probably active subunit of tyrosine hydroxylase of molecular weight 62,000. Phosphorylation of the hydroxylase increased its activity by 2-fold, and was associated with an increase in Vm without any change in Km for either substrate or cofactor. We propose that the pool of native tyrosine hydroxylase is composed of a mixture of enzyme molecules in both active and probably inactive forms, that the active form is phosphorylated, and that phosphorylation produces an active form of the enzyme at the expense of an inactive one.
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PMID:Direct phosphorylation of brain tyrosine hydroxylase by cyclic AMP-dependent protein kinase: mechanism of enzyme activation. 3 81

A protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) which catalyzes the phosphorylation of troponin T, phosvitin and casein has been purified over 2000 fold from rabbit skeletal muscle. The partial purification of this new enzyme, designated troponin T kinase, involves precipitation of contaminating proteins at pH 6.1, fractionation of the supernatant with (NH4)2SO4 and successive column chromatographies on DEAE-cellulose, hydroxyapatite and Sepharose 6B. The chromatographic patterns on DEAE-cellulose and hydroxyapatite columns show two peaks of troponin T kinase activity. Gel filtration experiments indicate the existence of multiple, possibly aggregated, forms of the enzyme. The purified enzyme does not catalyze the phosphorylation of phosphorylase b, troponin I, troponin C, tropomyosin, protamine, or myosin light chain 2 nor does it catalyze the interconversion of glycogen synthase I into the D form. Troponin T kinase is not affected by the addition of cyclic nucleotides or AMP to the reaction mixture. Divalent cations (other than Mg2+, required for the reaction) do not stimulate the enzyme, and several are inhibitory. Other characteristics of the reaction catalyzed by troponin T kinase, such as Km values for ATP and substrate proteins, pH optima, effect of the concentration of Mg2+, substitution of ATP for GTP have also been studied.
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PMID:Purification and properties of troponin T kinase from rabbit skeletal muscle. 3 14

A method for the preparation of a homogenous catalytic subunit of adenosine 3':5'-monophosphate-dependent protein kinase from pigeon breast muscle was developed. The molecular weight of the enzyme as determined by electrophoresis in the presence of sodium dodecyl sulfate was found to be 42000. The pH optimum of the catalytic subunit was around 8.0. The active site of the catalytic subunit was studied using some derivatives of ATP, containing different reactive groups in the triphosphate chain of the molecule. It may be assumed that the pH optimum of the enzyme inactivation by adenosine 5'-chloromethylpyrophosphonate and the protective effect of ATP suggest covalent binding of the imidazole ring in the enzyme active site. The kinetic mechanism of the protein kinase reaction was studied using the initial rate experiments and reaction product inhibition. The results obtained were consistent with a random Bi-Bi kinetic mechanism.
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PMID:[Some properties of the catalytic subunit of adenosine 3':5'-monophosphate-dependent protein kinase from pigeon breast muscle]. 3 26

cAMP independent glycogen synthase kinase and phosvitin kinase activity was purified from the 180 000 x g supernatant of human polymorphonuclear leukocytes by ammonium sulphate precipitation and phosphocellulose chromatography. The cAMP independent glycogen synthase kinase eluted from the phosphocellulose at 0.54 M NaCl (peak A) separate from the major phosvitin kinase eluting at 0.68 M NaCl (peak B). The kinase activity of both peaks tended to form aggregates, but in the presence of 0.6 M NaCl, the peak B enzyme had Mr 250 000, 7.2S and the peak A enzyme Mr 38 000, 3.8S. The ratio between synthase kinase and phosvitin kinase activity in peak A was 1:3.2 and in peak B 1:31.4. In addition the kinase activities differed with respect to sensitivity to temperature, ionic strength and CaCl2. It is suggested that the peak A enzyme represents the cAMP independent glycogen synthase kinase of leukocytes, whereas the peak B enzyme is a phosvitin kinase, which is insignificantly contaminated with some synthase kinase (peak A) and contains a separate, second synthase kinase. Synthase kinase had Kmapp 4.2 microM for muscle glycogen synthease I and Kmapp 45 microM for ATP. GTP was a poor substrate. The activity was not influenced by cyclic nucleotides, Ca2+, or glucose-6-P. Synthase I from muscle and leukocytes was phosphorylated to a ratio of independence of less than 0.05.
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PMID:Purification and properties of cAMP independent glycogen synthase kinase and phosvitin kinase from human leukocytes. 4 Jan 8

Most of the cyclic AMP-dependent protein kinase activity in propylthiouracil-induced goiters and control rat thyroid glands was found in the soluble fraction. The activity in the particulate fractions was cyclic AMP-independent. Protein kinase activity was 2--3-fold higher in all the subcellular fractions of goitrous tissue than of control tissue. In the presence of Triton X-100, both groups showed a significant increase in kinase activity in all subcellular fractions, and the kinase activity in the particulate fractions could now be slightly stimulated by cyclic AMP. Again, enzyme activity in fractions from goiters was significantly higher than in control tissue. Two major peaks, Types I and II, of soluble cyclic AMP-dependent protein kinase activity could be separated by DEAE-cellulose chromatography. Chronic in vivo stimulation by TSH was associated with a selective increase in Type II isoenzyme activity. Elution and pH profiles, dissociation of subunits with 0.5 M NaCl, and activity ratios (-cyclic AMP/+cyclic AMP) for various substrates for Type II isoenzyme in goitrous and control tissue were similar. The elevated activity in goitrous tissue was manifested by an increase in V for histone, ATP, Mg2+ and cyclic AMP, with no change in the apparent Km.
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PMID:Properties of cyclic AMP-dependent protein kinase in normal and goitrous rat thyroid gland. 4 80

Kinase activity detected in immune complexes containing the src gene product of the avian sarcoma virus has been reported. To further characterize this immune complex kinase, we developed a routine quantitative assay involving trichloroacetic acid precipitation on filters. The enzyme reaction required either Mg2+ or Mn2+, but was inactive with Ca2+. The kinetics of the phosphorylation reaction indicated a transient enzyme activity limited by rapid substrate-dependent inactivation of the enzyme. A variety of nucleoside and deoxyribonucleoside triphosphates (dATP, ATP, GTP, CTP, dGTP, TTP, dCTP) served as phosphoryl donors. The phosphorylation of immunoglobulin G was inhibited by the presence of nucleoside diphosphates. Deoxyribonucleoside diphosphates can either stimulate or inhibit the kinase reaction depending upon the concentration used. The unusual enzymatic properties of the immune complex kinase raise the possibility that the enzyme does not function as a protein kinase in vivo, but rather belongs to a different class of kinases (nucleotide kinases) which adventitiously phosphorylates immunoglobulin G when immunoprecipitated with immune serum.
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PMID:Characterization of an immune complex kinase in immunoprecipitates of avian sarcoma virus-transformed fibroblasts. 4 53

Urocaninase (EC 4.2.1.4.9) from rat liver homogenate has been purified, using protein precipitation at pH 4,8, ammonium sulfate fractionation, gel-filtration through Sephadex G-200 and chromatography on DEAE-cellulose. Upon DEAE-cellulose chromatography urocaninase is separated from the proteins possessing the activity of 3',5'-AMP-dependent protein kinase. The purified enzyme becomes activated after addition of ATP and exogenous protein kinase or one of the fractions resulting from DEAE-cellulose chromatography. Using [gamma-32P]ATP, it has been shown that such activation is accompanied by incorporation of at least one phosphate residue into the enzyme molecule. The mol. weight of urocaninase as determined by gel-filtration is about 110 000. The Km value for urocanate is 15 . 10(-6) M, the isoelectric point lies at 5,6. The mechanism of regulation of the urocaninase activity in rat liver is discussed.
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PMID:[Purification, properties and regulation of urocaninase from rat liver]. 4 82

We have studied the effect of protein phosphokinase (EC 2.7.1.37; ATP:protein phosphotransferase) and phosphoprotein phosphatase (EC 3.1.3.16; phosphoprotein phosphohydrolase) on reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) activity of Rous sarcoma virus. Protein kinase from Rous sarcoma virus-transformed chick embryo fibroblasts was purified by DEAE-cellulose chromatography, Sephadex gel filtration, and isoelectric focusing. Purified reverse transcriptase from Rouse sarcoma virus was preincubated with protein kinase and ATP under conditions allowing incorporation of phosphate into substrate protein. After the preincubation, reverse transcriptase activity was assayed in the presence of poly(rA).oligo(dT) as template. A 2- to 5-fold increase of reverse transcriptase activity was found after the preincubation of reverse transcriptase with protein kinase and ATP. Incubation of reverse transcriptase with heat-treated, inactive protein kinase and ATP had no effect on transcriptase activity. When the transcriptase preparation was incubated with protein kinase and [gamma-32P]ATP and subsequently purified by chromatography on phosphocellulose and Sephadex gel filtration, significant amounts of 32P-labeled proteins were found in the fractions exhibiting reverse transcriptase activity, suggesting 32P incorporation into transcriptase or transcriptase-associated proteins. A 20-60% decrease of reverse transcriptase activity was observed after incubation of reverse transcriptase with phosphatase. The results suggest that phosphorylative modification of reverse transcriptase may be critical in the regulation of reverse transcriptase-catalyzed DNA synthesis.
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PMID:Protein kinase and its regulatory effect on reverse transcriptase activity of Rous sarcoma virus. 5 72

The structural polypeptides of purified viper range in molecular weight from 11,000 to 97,000 daltons and consist of 3 major and about 13 minor polypeptides. The virus contains both protein kinase and reverse transcriptase activities. Several of the structural polypeptides are phosphorylated in vitro by the virus-associated protein kinase. However, most (possibly all) of the viral structural polypeptides are not phosphorylated in vivo. DeoxyATP is as efficient as ATP in donating phosphate for in vitro phosphorylation of viral proteins. In vitro protein phosphorylation always precedes transcription and the virus-associated protein kinase and reverse transcriptase activities can be partially separated by sedimentation in a sucrose gradient.
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PMID:Structural and enzymatic characterization of viper C-type virus. 5 28

Activatable cholesterol esterase and triacylglycerol lipase of rat adrenal were 58-69% recovered in the 100 000 X g supernatant fraction. Activatable triacylglycerol lipase activity was differentiated from the activity of acid lipase and lipoprotein lipase also found in this fraction. Cholesterol esterase was activated 39.7 +/- 13.6% (S.D.) and triacylglycerol lipase 11.9 +/- 2.9% in a reaction dependent on ATP, cyclic AMP, and protein kinase. The two activities were shown by differential inhibition by an organophosphate, and by partial separation on salting out, to be largely due to separate enzymes. The two enzymes bound tightly to substrate emulsions with quantitatively similar distribution between competing emulsions, suggesting concerted binding. Coinciding gel filtration patterns reinforced, The hypothesis of a lipase complex. Cholesterol esterase comprised a major component of higher apparent Km for substrate and molecular weight 3-10(5)-6-10(5) by gel filtration and a minor component of lower apparent Km and heterogeneous molecular weight above 1 million, which was found mostly in complex and lipid.
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PMID:Activatable cholesterol esterase and triacylglycerol lipase activities of rat adrenal and their relationship. 6 45


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