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)

The multifunctional Ca2+/calmodulin-dependent protein kinase purified from rat brain cytosol undergoes an intramolecular self-phosphorylation or autophosphorylation. Autophosphorylation produces two strikingly different effects on kinase activity that are dependent on the level of ATP used in the reaction. At low but saturating levels of ATP (5 microM), autophosphorylation causes a 75% reduction in kinase activity, with the residual activity still retaining a dependence on Ca2+ and calmodulin. By contrast, at high but physiological levels of ATP (500 microM), the kinase is converted by autophosphorylation to a form that is autonomous of Ca2+ and calmodulin, with no accompanying reduction in activity. The extent of phosphate incorporation does not determine whether the kinase becomes inhibited or autonomous. Autophosphorylated kinase shows the functional change characteristic of the ATP concentration used during the reaction--inhibited at low ATP and autonomous at high ATP--even when compared at the same level of incorporated phosphate. ATP appears to regulate the site(s) phosphorylated during activation of the kinase and thereby modulates the dual effects of autophosphorylation. Events triggered by transient elevations of cellular Ca2+ may be potentiated and retained by generation of the Ca2+/calmodulin-independent protein kinase activity.
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PMID:Activation of the multifunctional Ca2+/calmodulin-dependent protein kinase by autophosphorylation: ATP modulates production of an autonomous enzyme. 346 20

cDNA clones coding for the beta subunit of rat brain type II Ca2+/calmodulin-dependent protein kinase were isolated and sequenced. The clones, including one containing the entire coding region, hybridize at high stringency to a single band of poly(A)+ RNA of length 4.8 kilobases. The subunit coded for by the clones was identified by in vitro transcription of the cDNA followed by translation of the resulting RNA. The DNA sequence of the clones contains a single long open reading frame (1626 nucleotides) coding for a protein of 542 amino acids with a molecular weight of 60,333, the amino-terminal half of which is homologous to several other protein kinases. Potential ATP- and calmodulin-binding domains were identified. Two independent clones contain an identical 45-nucleotide deletion, relative to the clones described above, resulting in a shorter open reading frame coding for a protein of molecular weight 58,000. This suggests that the minor, 58-kDa beta' subunit of the type II Ca2+/calmodulin-dependent kinase may be synthesized on a separate message.
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PMID:Deduced primary structure of the beta subunit of brain type II Ca2+/calmodulin-dependent protein kinase determined by molecular cloning. 347 Jul 58

Ca2+/calmodulin-dependent protein kinase II contains two types of subunit, alpha (Mr 50,000) and beta (Mr 60,000/58,000), both of which undergo Ca2+/calmodulin-dependent autophosphorylation. Autophosphorylation is known to convert the enzyme to a Ca2+/calmodulin-independent form. In the present study, we have characterized the autophosphorylation sites on rat forebrain Ca2+/calmodulin-dependent protein kinase II that are most likely to be responsible for the generation of Ca2+/calmodulin-independence. Under conditions (0 degree C, low concentrations of ATP) sufficient to generate close to maximal Ca2+/calmodulin-independence, only a few of the phosphorylatable sites on the enzyme became phosphorylated. These autophosphorylation sites were examined by phospho amino acid analysis, two-dimensional thermolytic phosphopeptide mapping, and high-performance liquid chromatography. The time course of phosphorylation of threonine in both alpha and beta subunits was similar to the time course of the generation of Ca2+/calmodulin-independence. Moreover, the time course of phosphorylation of one set of peptides, referred to as peptide 1/1', present in both alpha and beta subunits was similar to the time course of the generation of Ca2+/calmodulin-independence. Threonine was the only amino acid phosphorylated in peptide 1/1'. An additional peptide, referred to as peptide 2, was phosphorylated in the beta subunit. The time course of phosphorylation of peptide 2, which also contained only phosphothreonine, did not parallel the time course of the generation of Ca2+/calmodulin-independence. It is likely that the phosphorylation of a threonine residue on peptide 1/1' is responsible for the generation of Ca2+/calmodulin-independence of Ca2+/calmodulin-dependent protein kinase II.
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PMID:Ca2+/calmodulin-dependent protein kinase II: identification of autophosphorylation sites responsible for generation of Ca2+/calmodulin-independence. 347 99

Purified brain tubulin subjected to an exhaustive phosphatase treatment can be rephosphorylated by casein kinase II. This phosphorylation takes place mainly on a serine residue, which has been located at the carboxy-terminal domain of the beta-subunit. Interestingly, tubulin phosphorylated by casein kinase II retains its ability to polymerize in accordance with descriptions by other authors of in vivo phosphorylated tubulin. Moreover, the V8 phosphopeptide patterns of both tubulin phosphorylated in vitro by casein kinase II and tubulin phosphorylated in vivo in N2A cells are quite similar, and different from that of tubulin phosphorylated in vitro by Ca/calmodulin-dependent kinase II. On the other hand, we have found an endogenous casein kinase II-like activity in purified brain microtubule protein that uses GTP and ATP as phosphate donors, is inhibited by heparin, and phosphorylates phosphatase-treated tubulin. Thus it appears that a casein kinase II-like activity should be considered a candidate for the observed phosphorylation of beta-tubulin in vivo in brain or neuroblastoma cells.
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PMID:Tubulin phosphorylation by casein kinase II is similar to that found in vivo. 347 37

Phospholamban, the cardiac sarcoplasmic reticulum proteolipid, is phosphorylated by cAMP-dependent protein kinase, by Ca2+/phospholipid-dependent protein kinase, and by an endogenous Ca2+/calmodulin-dependent protein kinase, the identity of which remains to be defined. The aim of this study was therefore to characterize the latter kinase, called phospholamban kinase. Phospholamban kinase was purified approximately 42-fold with a yield of 11%. The purified fraction exhibits a specific activity of 6.5 nmol of phosphate incorporated into exogenous phospholamban per minute per milligram of protein. Phospholamban kinase appears to be a high molecular weight enzyme and presents a broad substrate specificity, synapsin-1, glycogen synthase, and smooth muscle myosin regulatory light chain being the best substrates. Phospholamban kinase phosphorylates synapsin-1 on a Mr 30 000 peptide. The enzyme exhibits an optimum pH of 8.6, a Km for ATP of 9 microM, and a requirement for Mg2+ ions. These data suggest that phospholamban kinase might be an isoenzyme of the multifunctional Ca2+/calmodulin-dependent protein kinase. Consequently we have searched for Mr 50 000-60 000 phosphorylatable subunits among cardiac sarcoplasmic reticulum proteins. A Mr 56 000 protein was found to be phosphorylated in the presence of Ca2+/calmodulin. Such phosphorylation alters the electrophoretic migration velocity of the protein. In addition, this protein that binds calmodulin was always found to be present in fractions containing phospholamban kinase activity. This Mr 56 000 protein is therefore a good candidate for being a subunit of phospholamban kinase. However, the Mr 56 000 calmodulin-binding protein and the Mr 53 000 intrinsic glycoprotein which binds ATP are two distinct entities.
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PMID:Characterization and partial purification of cardiac sarcoplasmic reticulum phospholamban kinase. 373 Mar 67

Tyrosine-specific protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity was measured in normal human nonadherent peripheral blood lymphocytes using synthetic peptide substrates having sequence homologies with either pp60src or c-myc. A high level of tyrosine-specific protein kinase activity was found associated with the cell particulate fraction (100 000 X g pellet). High-pressure liquid chromatography and phosphoamino acid analysis of the synthetic peptide substrates substantiated the phosphorylation of tyrosine residues by the particulate fraction enzyme. The human enzyme was also capable of phosphorylating a synthetic random polymer of 80% glutamic acid and 20% tyrosine. Enzyme activity was half-maximal with 22 microM Mg X ATP and had apparent Km values for the synthetic peptides from 1.9 to 7.1 mM. The enzyme preferred Mg2+ to Mn2+ for optimal activity and was stimulated 2-5-fold by low levels (0.05%) of some ionic as well as non-ionic detergents including deoxycholate, Nonidet P-40 and Triton X-100. The enzyme activity was not stimulated by N6;O2'-dibutyryl cyclic AMP (100 microM), N6;O2'-dibutyryl cyclic GMP (100 microM), Ca2+ (200 microM), insulin (1 microgram/ml) or homogeneous human T-cell growth factor (3 micrograms/ml) under the conditions used. Alkaline-resistant phosphorylation of particulate proteins in vitro revealed protein bands with Mr 59 000 and 54 000 suggesting that there are endogenous substrates for the human lymphocyte tyrosine protein kinase.
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PMID:High tyrosine-specific protein kinase activity in normal human peripheral blood lymphocytes. 403 88

After bacteriophage T7 infection, a protein kinase (EC 2.7.1.37; ATP:protein phosphotransferase) activity can be demonstrated in E. coli in vivo by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Cell-free extracts catalyzed the transfer of the terminal phosphoryl group of [(gamma)-(32)P]ATP to endogenous protein acceptor or to added histone. The bond between phosphate and protein shows the characteristics of serine phosphate: it is stable in 1 N HCl (100 degrees ) and cleaved by 1 N KOH (37 degrees ) and by alkaline phosphatase treatment. Moreover, after partial acid hydrolysis, radiophosphate migrates with marker O-phosphoserine on polyethyleneimine-cellulose thin-layer chromatograms. Enzyme activity in uninfected cells is negligible. Ultraviolet irradiation of the phage genome prevents the appearance of the protein kinase; irradiation of the host genome does not. The enzyme activity occurs 4 min after infection and its gene maps in the early region (promoter proximal to gene 1). Ribosomal proteins are phosphorylated in vivo and are substrates in vitro. Enzyme activity in vitro is not changed by addition of cyclic AMP or cyclic GMP.
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PMID:Protein kinase induction in Escherichia coli by bacteriophage T7. 459 95

Increased intracellular adenosine 3':5'-monophosphate (cAMP) levels and activation of cAMP-dependent protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) in vivo were correlated in mouse neuroblastoma cells grown in the presence of 1 mM-6N,O2'-dibutyryl 3':5'-monophosphate (Bt2cAMP). The time course for activation showed that cAMP-dependent protein kinases were activated by 30 min. A heat-stable inhibitor protein inhibited a majority of activated cAMP-dependent protein kinase. Activation of cAMP-dependent protein kinase caused additional phosphorylation of proteins when compared with untreated control cells, as demonstrated by endogenous phosphorylation of proteins in vitro using [gamma-32P]ATP and analysis by two-dimensional polyacrylamide gel electrophoresis. The phosphorylation data show selective phosphorylation of specific proteins by cAMP-independent and cAMP-dependent protein kinase. Among the proteins in the postmitochondrial supernatant fraction phosphorylated by cAMP-dependent protein kinases, two proteins with a molecular weight of 43,000 were heavily phosphorylated. It is suggested that phosphorylation of cellular proteins by cAMP-dependent protein kinases might be involved in the cAMP-modulated biochemical changes in neuroblastoma cells.
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PMID:Phosphorylation of endogenous proteins by adenosine 3':5'-monophosphate-dependent protein kinase in mouse neuroblastoma cells. 625 79

The transforming protein sequences translated from the Rous avian and Moloney murine sarcoma virus src genes are shown to be related to the catalytic chain of bovine cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37). The avian transforming protein, also a protein kinase, shows greatest homology with the bovine protein kinase in the carboxyl-terminal half, where the protein kinase activity is localized. Moreover, lysine occurs in the inferred transforming protein sequences at the position homologous with the proposed ATP-binding lysine of the bovine protein kinase. This relationship is consistent with the hypothesis that the src genes originated in the host genomes, in which they are members of a superfamily of distantly related protein kinases that are normal constituents of mammalian cells. In the host, these sequences are much more highly conserved than in the viruses.
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PMID:Viral src gene products are related to the catalytic chain of mammalian cAMP-dependent protein kinase. 628 46

A soluble Ca2+/calmodulin-dependent protein kinase has been purified from rat brain to near homogeneity by using casein as substrate. The enzyme was purified by using hydroxylapatite adsorption chromatography, phosphocellulose ion-exchange chromatography, Sepharose 6B gel filtration, affinity chromatography using calmodulin-Sepharose 4B, and ammonium sulfate precipitation. On sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gels, the purified enzyme consists of three protein bands: a single polypeptide of 51 000 daltons and a doublet of 60 000 daltons. Measurements of the Stokes radius by gel filtration (81.3 +/- 3.7 A) and the sedimentation coefficient by sucrose density sedimentation (13.7 +/- 0.7 S) were used to calculate a native molecular mass of 460 000 +/- 29 000 daltons. The kinase autophosphorylated both the 51 000-dalton polypeptide and the 60 000-dalton doublet, resulting in a decreased mobility in NaDodSO4 gels. Comparison of the phosphopeptides produced by partial proteolysis of autophosphorylated enzyme reveals substantial similarities between subunits. These patterns, however, suggest that the 51 000-dalton subunit is not a proteolytic fragment of the 60 000-dalton doublet. Purified Ca2+/calmodulin-dependent casein kinase activity was dependent upon Ca2+, calmodulin, and ATP X Mg2+ or ATP X Mn2+ when measured under saturating casein concentrations. Co2+, Mn2+, and La3+ could substitute for Ca2+ in the presence of Mg2+ and saturating calmodulin concentrations. In addition to casein, the purified enzyme displayed a broad substrate specificity which suggests that it may be a "general" protein kinase with the potential for mediating numerous processes in brain and possibly other tissues.
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PMID:Purification and characterization of a Ca2+/calmodulin-dependent protein kinase from rat brain. 650 30


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