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)

Characteristics of the autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) from the cytosol and in the postsynaptic densities (PSD) of rat brain were investigated. Several proteins were surveyed for their abilities to serve as a substrate for non-autophosphorylated and autophosphorylated CaM kinase IIs from the cytosol and PSD. The tested substrates were separated into two groups. Autophosphorylation of the kinase slightly decreased or did not change its activities towards substrates of the first group: myosin light chain of chicken gizzard, synapsin I, tau factor and microtubule-associated protein 2. In contrast, autophosphorylation of the enzyme increased its activities towards substrates of the second group: syntide-2, histone H1, calcineurin and myelin basic protein. The Ca2+/calmodulin-independent kinase activity increased by autophosphorylation with any of substrates tested. Similar results were obtained with the cytosolic and PSD CaM kinase II. Trifluoperazine and mastoparan, calmodulin binding antagonists, inhibited the activity of the non-autophosphorylated CaM kinase II, but had no effect or only a slight inhibitory effect on the activity of the autophosphorylated CaM kinase II, indicating that the autophosphorylated kinase has no requirement for calmodulin for Ca(2+)-dependent activity and/or a higher affinity for calmodulin The results suggest that the autophosphorylation of CaM kinase II is a subtle mechanism for regulating the interaction between the enzyme and substrate.
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PMID:Autophosphorylation of Ca2+/calmodulin-dependent protein kinase II: effects on interaction between enzyme and substrate. 164 40

The cDNAs encoding the alpha and beta subunits of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) were ligated into the bacterial expression vector pET and expressed in Escherichia coli. The bacterially expressed alpha and beta subunits exhibited Ca2+/calmodulin-dependent activity and were easily purified to apparent homogeneity from cell extracts. To determine the minimum size required for catalytic activity and the properties of the calmodulin-binding domain, mutated CaM kinase II cDNAs were expressed in E. coli and the enzymatic property of expressed proteins was examined. The replacement of Thr-286 of the alpha subunit with the negatively charged amino acid Asp or that of Arg-283 with the neutral amino acid Gly induced the partially Ca2+ independent activity. The mutant enzymes alpha-I(delta 283-478) and alpha-II(delta 359-478), which truncated the C-terminal region of the alpha subunit, exhibited CaM kinase II activity and the activities of alpha-I(delta 283-478) and alpha-II(delta 359-478) were completely independent of and partially dependent on Ca2+ and calmodulin, respectively. However, the truncated protein alpha(delta 250-478), which was only 33 amino acids shorter than the alpha-I(delta 283-478) protein had no enzymatic activity, indicating that alpha-I(delta 283-478) was close to the minimum size of the active form. The mutant enzyme alpha(delta 291-315), which lacked the calmodulin-binding domain exhibited Ca2+ independent activity. The molecular mass was, however, smaller than that expected from the amino acid sequence. The mutant enzyme alpha(delta 304-315), which lacked the C-terminal half of the calmodulin-binding domain of the alpha subunit, however, exhibited Ca(2+)-independent activity without a reduction in molecular size, indicating that residues 304-315 of the alpha subunit constituted the core calmodulin-binding domain.
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PMID:Studies on the regulatory domain of Ca2+/calmodulin-dependent protein kinase II by expression of mutated cDNAs in Escherichia coli. 165 35

We found a novel 81-kDa acidic protein (ACAMP-81) in the bovine brain membrane fraction, which bound to calmodulin in a Ca(2+)-dependent manner. The present study reveals physicochemical properties and phosphorylation of this protein with various protein kinases in vitro. The Stokes radius and sedimentation coefficient were calculated to be 52 A and 2.05 S, respectively, suggesting that the structure of ACAMP-81 is highly elongated. Purified Ca2+/phospholipid-dependent protein kinase (protein kinase C), cAMP-dependent protein kinase, and Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II) catalyzed the incorporation of 1.46, 0.72, and 0.44 mol of phosphate/mol of ACAMP-81, respectively. The amino acid residues of ACAMP-81 phosphorylated by either protein kinase C or cAMP-dependent protein kinase were almost exclusively on serine. Sequential phosphorylation of ACAMP-81 by cAMP-dependent protein kinase and protein kinase C resulted in the additional incorporation of 1.15 mol of [32P]phosphate into ACAMP-81. Comparison of phosphopeptide maps of ACAMP-81 phosphorylated by each kinase revealed that there are two classes of phosphorylatable polypeptide, one is phosphorylatable by both protein kinases which contained two polypeptides and the others are specific sites for protein kinase C.
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PMID:Phosphorylation of bovine brain 81-kDa acidic calmodulin binding protein (ACAMP-81) in vitro. 165 83

A monoclonal antibody was made using the spleen cells of a mouse immunized with chick synaptic membranes and designated as mAb 1D12. It immunoprecipitated 25% of the omega-conotoxin binding protein but no dihydropyridine binding protein solubilized from chick brain membranes. By immunoblotting, a polypeptide of 58-kDa was identified as the antigen of this antibody in chick, rat, rabbit and guinea pig brain. Immunohistochemical observation indicated the immunoreactivity of mAb 1D12 to be localized in the synaptic regions of central and peripheral neurons. In peripheral organs, there was additional staining in the distal portions of nerve fibers. Immunoelectron microscopy showed immunoreactivity to be located in synaptic vesicle and presynaptic plasma membranes. In the subcellular fractionation of rat brain, 58-kDa protein was recovered in the fractions of synaptic vesicles and plasma membranes but not soluble proteins. This protein could be extracted from membranes by Triton X-100 but treatment with EDTA, acid, base or high salt failed to have such effect. Solubilized 58-kDa protein of rat brain was purified by immunoaffinity chromatography using mAb 1D12. Both protein kinase C and Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) phosphorylated purified 58-kDa protein, and maxima of 0.47 and 0.94 mol of phosphates, respectively, were incorporated per mol of 58-kDa protein. 58-kDa protein was not phosphorylated by either cAMP-dependent or cGMP-dependent protein kinase. When present in membranes, it was also phosphorylated by protein kinase C and CaM kinase II. Possible involvement of 58-kDa protein in the protein kinase C and CaM kinase II-mediated regulation of synaptic transmission in central and peripheral neurons is discussed.
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PMID:Protein kinase C and Ca2+/calmodulin-dependent protein kinase II phosphorylate a novel 58-kDa protein in synaptic vesicles. 165 60

Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) is one of the predominant protein kinases in the brain. We found that CaM kinase II immunoreactivity was concentrated in the peripheral halos of Lewy bodies (LBs) in Parkinson's disease and Lewy body-like hyaline inclusions (LBHIs) in amyotrophic lateral sclerosis. An immunoelectron microscopic examination of LBs revealed that the filaments at the periphery of LBs were decorated with immunopositive deposits. Since CaM kinase II has a broad substrate specificity and can phosphorylate neurofilaments and other cytoskeletal proteins, it may play some role in the formation of LBs and LBHIs through the aberrant phosphorylation of the cytoskeletal elements in these inclusions.
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PMID:Ca2+/calmodulin-dependent protein kinase II immunoreactivity in Lewy bodies. 165 93

The molecular conformation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) from the rat forebrain and cerebellum was studied by means of EM using a quick-freezing technique. Each molecule appeared to be composed of two kinds of particles, with one larger central particle and smaller peripheral particles and had shapes resembling that of a flower with 8 or 10 "petals". A favorable shadowing revealed that each peripheral particle had a thin link to the central particle. We predicted that the 8-petal molecules and 10-petal molecules were octamers and decamers of CaM kinase II subunits, respectively, each assembled with the association domains of subunits gathered in the center, and the catalytic domains in the peripheral particles. Binding of antibodies to the enzyme molecules suggested that molecules with 8 and 10 peripheral particles were homopolymers composed only of beta subunit and of alpha subunit, respectively, specifying that CaM kinase II consists of homopolymer of either alpha or beta subunits.
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PMID:Structural features of Ca2+/calmodulin-dependent protein kinase II revealed by electron microscopy. 165 71

The effect of magnesium-free medium on electrical and CaM kinase II activity in the rat hippocampal slice was examined. Experimental slices were incubated in 2 mM Mg, then exposed to magnesium-free medium for 1 h. Control slices were concurrently run in 2 mM Mg. Slices were then frozen and CaM kinase II activity was measured in homogenates. Exposure of hippocampal slices to magnesium-free medium resulted in spontaneous epileptiform activity and a concurrent 38 +/- 5.47% decrease in CaM kinase II activity (range 38.8-75.4% of control; n = 7, P less than 0.001, paired Student's t test). The decrease in CaM kinase II activity was not reversible by treatment with protein phosphatases 1 and 2A (58.8 +/- 4.77% of control activity; range 28.6-69.7, P less than 0.01, paired Student's t-test), indicating that the decrease in CaM kinase II activity cannot be accounted for exclusively by autophosphorylation. The results demonstrate that magnesium-free medium treatment can induce spontaneous epileptiform activity and simultaneous changes in CaM kinase II activity.
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PMID:Exposure of hippocampal slices to magnesium-free medium produces epileptiform activity and simultaneously decreases calcium and calmodulin-dependent protein kinase II activity. 166 Apr

Calcium ion (Ca2+) is considered to be involved in the regulation of numerous cellular processes. CaM kinase II is present at the highest concentration in the brain and is considered to be involved in the regulation and coordination of numerous cellular processes. CaM kinase II is activated by Ca2+/calmodulin and simultaneously undergoes autophosphorylation. It has not been determined whether the enzyme is activated in the cell systems in response to the increase in cytoplasmic Ca2+ concentration. We have studied CaM kinase II in several kinds of cells including the primary cultures of cerebellar granule cells and the cell lines of rat embryo fibroblast 3Y1 cells, neuroblastoma cells, PC12 cells and C6 glioma cells. The immunohistochemical analysis demonstrated the presence of CaM kinase II in all of the cells examined. Furthermore, the kinase in cerebellar granule cells was activated by the stimulation of the glutamic acid receptor. Autophosphorylation of CaM kinase II in 3Y1 cells was stimulated by the addition of growth factors. These results suggest that CaM kinase II undergoes activation and autophosphorylation in response to various stimuli to the cells and is regulated in the dynamic state.
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PMID:[Regulation of Ca2+/calmodulin-dependent protein kinase II in the cell systems in response to cellular stimuli]. 166 Apr 42

1. Presynaptic or simultaneous pre- and postsynaptic voltage-clamp protocols were implemented in the squid giant synapse in order to determine the magnitude and time course of the presynaptic calcium current (ICa) and its relation to transmitter release before and after presynaptic injection of proteins. These included several forms of synapsin I, calcium-calmodulin-dependent protein kinase II (CaM kinase II) and avidin. 2. The quantities and location of these proteins were monitored by fluorescence video-enhanced microscopy during the electrophysiological measurements. 3. Presynaptic injection of dephosphorylated synapsin I inhibited synaptic transmission with a time course consistent with diffusion of the protein through the terminal and action at the active release zone. A mathematical model relating the diffusion of synapsin I into the terminal with transmitter release was developed to aid in the interpretation of these results. 4. Synapsin I inhibition of transmitter release was reversible. 5. The action of synapsin I was highly specific, as phosphorylation of the tail region only or head and tail regions prevented synapsin I from inhibiting release. 6. Injections of heat-treated synapsin I or of avidin, a protein with a size and isoelectric point similar to those of synapsin I, had no effect on transmitter release. 7. CaM kinase II injected presynaptically was found to facilitate transmitter release. This facilitation, which could be as large as 700% of the control response, was related to the level of penetration of the enzyme along the length of the preterminal A mathematical model of this facilitation indicates a reasonable fit between the distribution of CaM kinase II within the terminal and the degree of facilitation. 8. The overall shape of the postsynaptic response was not modified by either synapsin I or CaM kinase II injection. 9. The data suggest that, in addition to releasing transmitter, calcium also penetrates the presynaptic cytosol and activates CaM kinase II. When activated, CaM kinase II phosphorylates synapsin I, which reduces its binding to vesicles and/or cytoskeletal structures, enabling more vesicles to be released during a presynaptic depolarization. The amplitude of the postsynaptic response will then be both directly and indirectly regulated by depolarization induced Ca2+ influx. This model provides a molecular mechanism for synaptic potentiation.
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PMID:Regulation by synapsin I and Ca(2+)-calmodulin-dependent protein kinase II of the transmitter release in squid giant synapse. 167 19

The P0 protein in mammalian PNS myelin is known to undergo several posttranslational modifications, such as glycosylation, acylation, sulfation, and phosphorylation. Phosphorylation of purified P0 protein in vitro was studied comparatively using three enzymes, i.e., calcium/phospholipid-dependent protein kinase (protein kinase C), calcium/calmodulin-dependent protein kinase II (CaM kinase II), and the catalytic subunit of cyclic AMP-dependent protein kinase (A kinase). The phosphorylation of P0 protein by CaM kinase II was the greatest, followed by that by protein kinase C; phosphorylation by A kinase, however, was much lower. In order to identify phosphorylation sites, P0 protein was phosphorylated with [32P]ATP and each kinase and then digested with lysylendopeptidase. The resulting phosphopeptides were isolated by HPLC. Subsequent amino acid sequence analysis and comparison with the known sequence of P0 protein revealed that Ser181 and Ser204 were strongly phosphorylated by both protein kinase C and CaM kinase II. In addition, Ser214 was also phosphorylated by protein kinase C, but not by CaM kinase II. Because all of these sites are located in the cytoplasmic domain of P0 protein, phosphorylation may be important for maintenance of the major dense line of PNS myelin.
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PMID:Phosphorylation of P0 glycoprotein in peripheral nerve myelin. 170 69


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