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 adenosine 3",5"-monophosphate (cAMP)-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity of cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) from bovine heart is characterized. That the ATPase activity is intimately associated with the catalytic subunit of the enzyme is suggested by the following: (i) the similar dependences of ATPase and protein kinase activities on cAMP; (ii) the dissociation of ATPase activity from the holoenzyme on addition of cAMP and its co-elution with the catalytic subunit on gel filtration chromatography; (iii) the similarity of the relative effectiveness of divalent metal ions in ATPase and protein kinase catalysis; and (iv) the correspondence of kinetically determined Km(MgATP) and Ki(MgADP) values with thermodynamic dissociation constants determined by equilibrium dialysis. The hydrolysis of ATP is stimulated 10- to 20-fold by cAMP in the holoenzyme. The molar specific activity of the catalytic subunit ATPase is approximately 0.7 min-1 with Km(MgATP) = 5 muM. MgADP is a competitive inhibitor of the reaction with a Ki value of approximately muM. The order of the relative effectiveness of metal ions for both ATPase and peptide kinase activities is Mg2+ greater than Mn2+ greater than Ca2+. A possible interpretation of these observations is that the role that the metal ion plays is more directly manifested in bond-breaking than in bond-forming.
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PMID:Cyclic AMP-dependent ATPase activity of bovine heart protein kinase. 21 18

1. We have transfected the rat substance P receptor (SPR) cDNA into the leukemic T-lymphocyte cell line Jurkat (J-wt) in order to study the effects of substance P (SP) on lymphocyte signaling mechanisms and the resultant neuropeptide-induced immunological changes. 2. The SPR cDNA was transfected into J-wt by the method of electroporation. Clones expressing SPRs were selected using a functional assay that measured SP-induced mobilization of intracellular Ca2+ ([Ca2+]i) in a fluorescence activated cell sorter (FACS) and by their expression of specific 125I-SP binding. 3. One clone, J-SPR, was identified and shown by Northern blot and 125I-SP saturation binding techniques to express the 2.2-kb SPR message and approximately 50,000 SPRs/cell with a Kd of 0.3 nM, respectively. Stimulation of J-SPR by SP resulted in the rapid mobilization of [Ca2+]i. This response was dose dependent in the range 10(-11)-10(-6) M SP and was maximal at 10(-7) M SP, with an EC50 of 0.3-0.5 nM SP. We further demonstrated that the SPR is rapidly desensitized following SP stimulation and by activation of the cell's T-cell receptor (TCR). Whole-cell patch-clamp experiments on J-SPR show that SP stimulation induces a Cl- current by a Ca2+ mediated process dependent on Ca2+/calmodulin-dependent protein kinase (CaMK). 4. Stimulation of J-SPR by SP results in changes in the cell surface expression of a number of molecules that play important roles in cell adhesion and activation: the expression of LFA-1 is decreased, and CD2 and IL-2 receptors are increased by 30 min, 6 hr, and 24 hr, respectively, following stimulation, as assessed by antibody staining in a FACS. 5. The expression of functional SPRs in Jurkat lymphocytes will not permit a detailed examination of how the activation of SPRs result in altered immune responses and further elucidate the role this neuropeptide receptor plays in inflammation.
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PMID:Functional and immunological responses of Jurkat lymphocytes transfected with the substance P receptor. 128 54

To investigate the role of calmodulin in stimulus-secretion coupling in pancreatic acinar cells, we studied the effects of W-7, a calmodulin inhibitor, and KN-62, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II), on amylase secretion from rat pancreatic acini. Calmodulin inhibitor (W-7, 100 microM) and Ca2+/CaM kinase II inhibitor (KN-62, 10 microM) reduced amylase secretion stimulated by cholecystokinin (CCK) or carbachol. W-7 and KN-62 also inhibited amylase secretion stimulated by both calcium ionophore (A23187) and phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA). To clarify the role of calmodulin in the interaction of intracellular mediators, pancreatic acini were permeabilized with streptolysin O. Following permeabilization, amylase secretion was stimulated by submicromolar free Ca2+, and this Ca(2+)-dependent amylase secretion was enhanced by guanosine 5'-[gamma-thio]triphosphate (GTP gamma S), TPA or cyclic adenosine 3',5'-monophosphate (cAMP). W-7 and KN-62 had no effects on amylase secretion stimulated by Ca2+ alone, but inhibited the enhancement in Ca(2+)-dependent amylase secretion by GTP gamma S, TPA or cAMP. These data suggest that calmodulin plays an important role in Ca(2+)-dependent amylase secretion from pancreatic acinar cells and in the interaction between Ca2+ and other intracellular messengers.
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PMID:Effects of calmodulin inhibitors on amylase secretion from rat pancreatic acini. 128 79

Cholinergic stimulation of parietal cell secretion is mediated by an increase in intracellular calcium. KN-62, a selective inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMK II), has recently been synthesized (Tokomitsu et al. J. Biol. Chem. 265: 4315-4320, 1990). To define the role of CaMK II in parietal cell secretion, we determined the effects of KN-62 on secretagogue-stimulated acid secretion in isolated rabbit parietal cells. Pretreatment of parietal cells with KN-62 resulted in the inhibition of carbachol-stimulated [14C]aminopyrine uptake over a concentration range of 3 to 60 microM (IC50 of 20 microM). KN-62 (60 microM) reduced carbachol-stimulated aminopyrine uptake to unstimulated levels. KN-62 did not alter carbachol-stimulated increases in cytoplasmic free Ca2+ concentration. High concentrations of KN-62 (60 microM) elicited a small decrease in aminopyrine uptake stimulated by forskolin, but did not significantly inhibit histamine stimulation. A potent CaMK II activity was identified in total membrane from parietal cells. These results suggest that CaMK II may mediate cholinergic-stimulated parietal cell secretion.
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PMID:An inhibitor of Ca2+/calmodulin-dependent protein kinase II, KN-62, inhibits cholinergic-stimulated parietal cell secretion. 131 Feb 21

We surveyed rabbit brain cytosol for a new Ca2+/calmodulin (CaM)-dependent kinase. The renaturation blotting assay (RBA) exploits the ability of blotted SDS-denatured proteins to regain enzymic activity after guanidine treatment. Using RBA, we found that the eluate of rabbit brain cytosol from a CaM affinity column contains at least four electrophoretically distinct protein kinase bands which were autophosphorylated in a Ca2+/CaM-dependent manner. The 49 kDa band and the 60 kDa band were alpha and beta subunit of CaM kinase II, and the 42 kDa band was presumed to be CaM kinase I, but the 80 kDa band could not be attributed to any reported Ca2+/CaM-dependent protein kinases. The 80 kDa protein kinase was isolated by three-step chromatography. We examined the phosphorylation of exogenous substrates by 80 kDa protein kinase, and histone IIIs and myosin light chain were phosphorylated in a Ca2+/CaM-dependent manner. W-7, a specific inhibitor for calmodulin, inhibited this kinase activity, but KN-62, a specific inhibitor for CaM kinase II, had no effect on this protein kinase activity. Autoradiography using boiled rabbit brain homogenate as substrate showed three intrinsic substrates (80 kDa, 60 kDa and 42 kDa), which were phosphorylated in a Ca2+/CaM-dependent manner. These findings suggest that a new Ca2+/CaM-dependent protein kinase could be identified by the RBA.
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PMID:Identification of a 80 kDa calmodulin-binding protein as a new Ca2+/calmodulin-dependent kinase by renaturation blotting assay (RBA). 131 May 91

An antiserum raised against the region of the cardiac ryanodine receptor (residues 2805-2819) containing the phosphorylation site for multifunctional Ca2+/calmodulin-dependent protein kinase (CaM kinase) was used to identify the brain ryanodine receptor. This antiserum, which is cardiac isoform-specific, immunoprecipitated greater than 90% of the [3H]ryanodine receptor binding sites solubilized from guinea pig brain membranes. The immunoprecipitated brain receptor exhibited the characteristic cardiac-type mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The brain ryanodine receptor, like the cardiac ryanodine receptor, was a substrate for CaM kinase. Affinity-purified, site-specific antibodies completely blocked phosphorylation of both brain and cardiac receptors by CaM kinase, and two-dimensional peptide mapping identified the same major 32P-labeled peptide in receptors from both tissues. 125I-Labeled receptors also gave the same peptide maps. These results confirm that mammalian brain expresses the cardiac isoform of the ryanodine receptor. Furthermore, the unique CaM kinase phosphorylation site, which has been shown to regulate Ca2+ channel activity, is conserved.
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PMID:Cardiac-specific phosphorylation site for multifunctional Ca2+/calmodulin-dependent protein kinase is conserved in the brain ryanodine receptor. 131 25

Abnormal phosphorylation of the microtubule associated protein tau component of neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) may result from alterations in protein kinase expression. Calcium/calmodulin dependent protein kinase II (CaM kinase II) has been shown to phosphorylate tau in vitro in such a way to decrease its electrophoretic mobility. A68, apparently a modified form of tau in AD brain, also shows abnormal phosphorylation and slower mobility than tau. To further examine the role of CaM kinase II in AD, in situ hybridization studies were performed on tissues from rat, monkey and human to examine and compare the patterns of CaM kinase II mRNA expression in different brain regions. The most notable differences among the three species were observed in dendrites in layer I of isocortex, in the molecular layer of the dentate gyrus and stratum radiatum and stratum lacunosum-moleculare in hippocampus, where hybridization was detected in rat, but not in monkey or human brain. In addition, comparisons between tau and CaM kinase II mRNA expression were made in tissue from normal aged adults and AD patients, especially in areas prone to NFT formation. CaM kinase II and tau mRNAs were co-expressed in many neuronal populations, both those which are prone to NFT formation as well as those which are rarely affected by AD changes. No major differences in the relative abundance of either CaM kinase II or tau mRNA within particular neuronal populations was noted between normal aged and AD brain. Diminished hybridization was associated with serve neuronal pathology and cell loss.
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PMID:In situ hybridization of calcium/calmodulin dependent protein kinase II and tau mRNAs; species differences and relative preservation in Alzheimer's disease. 131 9

We have investigated regional and temporal alterations in Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) and calcineurin (Ca2+/calmodulin-dependent protein phosphatase) after transient forebrain ischemia. Immunoreactivity and enzyme activity of CaM kinase II decreased in regions CA1 and CA3, and in the dentate gyrus, of the hippocampus early (6-12 h) after ischemia, but the decrease in immunoreactivity gradually recovered over time, except in the CA1 region. Furthermore, the increase in Ca2+/calmodulin-independent activity was detected up to 3 days after ischemia in all regions tested, suggesting that the concentration of intracellular Ca2+ increased. In contrast to CaM kinase II, as immunohistochemistry and regional immunoblot analysis revealed, calcineurin was preserved in the CA1 region until 1.5 days and then lost with the increase in morphological degeneration of neurons. Immunoblot analysis confirmed the findings of the immunohistochemistry. These results suggest that there is a difference between CaM kinase II and calcineurin in regional and temporal loss after ischemia and that imbalance of Ca2+/calmodulin-dependent protein phosphorylation-dephosphorylation may occur.
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PMID:Regional and temporal alterations in Ca2+/calmodulin-dependent protein kinase II and calcineurin in the hippocampus of rat brain after transient forebrain ischemia. 131 54

The early events of signal transduction associated with interleukin-2 (IL-2) binding to its receptor were examined using a human IL-2 dependent T-cell line, Kit225. Cell cycle analysis showed that 90% of Kit225 cells were in the G0/G1 phase after a 72-hr incubation in the absence of exogenous IL-2. At this point, stimulation of the cells with IL-2 resulted in the rapid initiation of RNA and DNA synthesis by 9 and 20 hr, respectively. Within 5 min after addition of IL-2, rapid activation of tyrosine and ribosomal S6 kinases was detected. Addition of IL-2 also increased mRNA levels for c-fos, c-myc, IL-2 receptor alpha, and IL-2 receptor beta chain. These events increased in the absence of detectable changes in free cytosolic [Ca2+]i, inositol phosphate metabolism, or the activity of several kinases including cAMP-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase, or protein kinase C. These findings demonstrate that the signals triggered by IL-2 binding to its receptors are quickly transduced into the nucleus with increased mRNA transcription of activation-associated genes. Furthermore, the data indicate that tyrosine and ribosomal S6 kinases may be important for IL-2-induced cell growth.
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PMID:Signal transduction by interleukin 2 in human T cells: activation of tyrosine and ribosomal S6 kinases and cell-cycle regulatory genes. 131 23

Multifunctional calcium-calmodulin-dependent protein kinase (CaM kinase) transduces transient elevations in intracellular calcium into changes in the phosphorylation state and activity of target proteins. By fluorescence emission anisotropy, the affinity of CaM kinase for dansylated calmodulin was measured and found to increase 1000 times after autophosphorylation of the threonine at position 286 of the protein. Autophosphorylation markedly slowed the release of bound calcium-calmodulin; the release time increased from less than a second to several hundred seconds. In essence, calmodulin is trapped by autophosphorylation. The shift in affinity does not occur in a site-directed mutant in which threonine at position 286 has been replaced by a non-phosphorylatable amino acid. These experiments demonstrate the existence of a new state in which calmodulin is bound to CaM kinase even though the concentration of calcium is basal. Calmodulin trapping provides for molecular potentiation of calcium transients and may enable detection of their frequency.
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PMID:Calmodulin trapping by calcium-calmodulin-dependent protein kinase. 131 63


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