Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

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

Three protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) were detected when the soluble fraction of rabbit kidney medulla was chromatographed on DEAE-cellulose with a linear NaC1 gradient. The first two kinases eluted (Peak 1 and Peak II) were cyclic-AMP-dependent, wheras Peak III was cyclic-AMP-independent. A procedure was developed to separate the catalytic subunit of Peak II cyclic-AMP-dependent protein kinase (representing the bulk of the histone kinase activity) from Peak III protein kinase. In contrast to the catalytic subunit, Peak III protein kinase phosphorylated casein more rapidly than histone. Peak III was insensitive to the heat-stable protein inhibitor of cyclic-AMP-dependent protein kinases and appeared to have a higher requirement for ATP than did the catalytic subunit. Peak III catalyzed the conversion of glycogen synthase (UDPglucose:glycogen alpha-4-glucosyltransferase, EC 2.4.1.11) from the I (glucose-6-phosphate-independent) to the D (glucose-6-phosphate-dependent) form. This conversion was dependent on Mg-2+ and ATP and was unaffected by cyclic AMP, cyclic GMP, or the protein inhibitor. Glycogen synthase I in the soluble fraction of kidney medulla could be converted to the D form by endogenous glycogen synthase I kinase if Mg-2+ and ATP were added. Most of this glycogen synthase I kinase activity was unaffected by cyclic AMP or by the protein inhibitor, suggesting that Peak III may be of major importance in the regulation of glycogen synthase in vivo.
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PMID:Isolation of a glycogen synthase I kinase that is independent of adenosine 3':5'-monophosphate. 16 80

In cell homogenates of Dictyostelium discoideum, strain AX-2, four major soluble protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) and one membrane-associated protein kinase activity were identified. The enzymes showed high affinity for casein. One of the enzymes was purified by affinity chromatography on casein-coated Sepharose. The soluble high molecular weight enzymes phosphorylated histones, whereas the low molecular weight enzymes did not. The same protein kinase species were present in vegetative and aggregation-competent cells. Their specific activity, however, changed during the development to aggregation competence. None of the enzymes was stimulated by cyclic AMP or cyclic GMP, regardless of their origin from vegetative or aggregation-competent cells.
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PMID:Protein kinases of Dictyostelium discoideum, strain AX-2. 22 Oct 22

Protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) and cyclic adenosine 3',5'-monophosphate binding activities have been identified in zoospore extracts of the water mold Blastocladiella emersonii. More than 75% of these activities is found in the soluble fraction. Soluble protein kinase activity is resolved in three peaks(I, II and III) by DEAE-cellulose chromatography. Peak I is casein dependent and insensitive to cyclic AMP. Peak II is histone dependent and cyclic AMP independent; this enzyme is inhibited by the heat-stable inhibitor from bovine muscle. Peak III utilizes histone as substrate and is activated by cyclic AMP.
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PMID:Cyclic AMP-dependent and -independent protein kinases of the water mold, Blastocladiella emersonii. 22 Oct 23

Incubation of simian virus 40 (SV40) tumor (T) antigen-containing immunoprecipitates with [gamma-32P]ATP results in the incorporation of radioactive phosphate into large T antigen. Highly purified preparations of large T antigen from a SV40-transformed cell line, SV80, are able to catalyze the phosphorylation of a known phosphate acceptor, casein. The kinase activity migrates with large T antigen through multiple purification steps. Sedimentation analysis under non-T-antigen-aggregating conditions reveals that kinase activity and the immunoreactive protein comigrate as a 6S structure. The kinase activity of purified preparations of large T antigen can be specifically adsorbed to solid-phase anti-T IgG, and partially purified T antigen from a SV40 tsA transformation is thermolabile in its ability to phosphorylate casein when compared to comparably purified wild-type T antigen. These observations indicate that the SV40 large T antigen is closely associated with protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity.
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PMID:Protein kinase activity associated with simian virus 40 T antigen. 22 52

Triiodothyronine (T3) administration to thyroidectomized rats induces a significant increase in the nucleolus-associated protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity. The general properties of the protein kinase solubilized from liver nucleoli have been investigated. Mg2+ (20 mM) is essential for the reaction and an appropriate concentration of NaCl (100 mM) is required to achieve maximal phosphorylation rates. The optimal pH for casein phosphorylation is 7.6. The kinase phosphorylates casein more efficiently than phosvitin and displays an almost undetectable activity towards histones and protamine. No significant stimulation of the kinase activity by cyclic AMP has been detected. The apparent Km values for casein and ATP are 1.5 mg/ml and 1.5-10(-5) M, respectively, and are not affected by the hormone administration.
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PMID:Increased activity of rat liver nucleolar protein kinase following triiodothyronine administration. 92 18

The phosphorylation in vitro and in vivo of tubulin isolated from HeLa cells has been examined during the cell cylce. The results obtained indicate that: (a) the protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity present in the microtubules, and measured in vitro with exogenous casein as substrate, is maximal in M cells, whereas that present in the cytosol is nearly constant during the S, G-2, and M stages, and decreases during G-1; (b) the patterns through the cell cycle of the maximal number of tubulin sites phosphorylated in vitro and of the microtubular protein kinase activity are similar; (c) the degree of tubulin phosphorylation in vivo is 2- to 3-fold higher in the microtubules isolated from the S and M stages of the cell cycle, than those from G-1 and G-2. This variable phosphate content of tubulin through the cell cycle suggests that such covalent modification might be important to enable tubulin to carry over some of its functions during the cell cycle.
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PMID:Changes in microtubule phosphorylation during cell cycle of HeLa cells. 105 73

The protein substrate specificity of the catalytic subunit of rabbit skeletal muscle cyclic AMP-dependent protein kinase (EC 2.7.1.37; ATP:protein phosphotransferase) has been studied using genetic variants of beta casein. It was found that beta casein-B was phosphorylated at a much greater rate than beta caseins A1, A2, A3, or C. The enhanced phosphorylation of beta casein-B, as compared with the most common variant A2, was attributed to an arginine substitution for a serine at position 122, which caused a nearby residue, serine 124, to become a phosphorylation site for the protein kinase. These results further support the concept that the local primary structure is important in specificity and that arginine may be a specific determinant common to all the local phosphorylation site sequences recognized by the cyclic AMP-dependent protein kinase.
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PMID:Substrate specificity of the cyclic AMP-dependent protein kinase. 105 31

Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) has been purified from hen whole brain. The enzyme was purified 3000-fold using phosphocellulose and calmodulin-Agarose column chromatography. The specific activity was 200 nmol/min/mg protein. Microtubule associated protein-2 (MAP-2) was used as a substrate to assess the activity of the enzyme during purification and for its characterization. CaM-kinase II consisted of alpha and beta/beta' subunits of molecular weights 46,000 and 55,000/52,000, respectively. The ratio of alpha to beta/beta' subunits was 3:1 in the enzyme purified from the whole brain. The enzyme exhibited broad substrate specificity and phosphorylated myelin basic protein, MAP-2, histone II, histone VIII, casein, tubulin, myosin light chains, glycogen synthase, and phosvitin in decreasing order. Phosphorylase b was phosphorylated at a negligible rate. Autophosphorylation of CaM-kinase II for 10 min in the presence of calcium and calmodulin decreased its total activity to 33%, and calcium/calmodulin-independent activity reached 30% after 1 min and then dropped to 14% after 10 min of autophosphorylation. The Km value of ATP was 19 +/- 1.3 microM, and the K0.5 values of calcium and calmodulin were 4.4 +/- 0.5 and 3.0 +/- 0.5 microM, respectively. The latter were determined using myelin basic protein as the substrate. CaM-kinase II exhibited great differences in the calmodulin requirement for phosphorylation of MAP-2, histone II and myelin basic protein. MAP-2 required the least amount of calmodulin for its phosphorylation. Autophosphorylation of CaM-kinase II resulted in decreased mobility of the alpha-subunit but apparently not of the beta/beta' subunits in sodium dodecyl/sulfate-polyacrylamide gel. Antiserum was raised against the CaM-kinase II alpha subunit and used for testing cross-reactivity of hen brain enzyme with that of other species. The antiserum which reacted with both alpha and beta subunits of hen brain CaM-kinase II cross-reacted with only the alpha subunit of rat, mouse, rabbit, cat, dog, pig and human brain samples. The purified hen brain CaM-kinase II is a multifunctional enzyme and resembled rat brain CaM-kinase II in several properties. Immunocross-reactivity suggested that there was similarity in the alpha but not the beta/beta' subunits of the hen brain enzyme and the brain enzyme of other species.
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PMID:Ca2+/calmodulin-dependent protein kinase II from hen brain. Purification and characterization. 131 5


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