Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

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

Purified plasma membranes from the yeast Saccharomyces cerevisiae bind about 1.2 pmol of cAMP/mg of protein with high affinity (Kd = 6 nM). By using photoaffinity labeling with 8-N3-[32P]cAMP, we have identified in plasma membrane vesicles a cAMP-binding protein (Mr = 54,000) that is present also in bcy1 disruption mutants, lacking the cytoplasmic R subunit of protein kinase A (PKA). This argues that it is genetically unrelated to PKA. Neither high salt, nor alkaline carbonate, nor cAMP extract the protein from the membrane, suggesting that it is not peripherally bound. The observation that (glycosyl)phosphatidylinositol-specific phospholipases (or nitrous acid) release the amphiphilic protein from the membrane, thereby converting it to a hydrophilic form, indicates anchorage by a glycolipidic membrane anchor. Treatment with N-glycanase reduces the Mr to 44,000-46,000 indicative of a modification by N-linked carbohydrate side chain(s). In addition to the action of a phospholipase, the efficient release from the membrane requires the removal of the carbohydrate side chain(s) or the presence of high salt or methyl alpha-mannopyranoside, suggesting complex interactions with the membrane involving not only the glycolipidic anchor but also the glycan side chain(s). Topological studies show that the protein is exposed to the periplasmic space, raising intriguing questions for the function of this protein.
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PMID:A cAMP-binding ectoprotein in the yeast Saccharomyces cerevisiae. 165 42

Enzymatically active, detergent-solubilized purified hormone-sensitive lipase (HSL) was incorporated into phosphatidylcholine (PC) vesicles, using a detergent-dialysis procedure with small PC vesicles, obtained by sonication, as phospholipid source and CHAPS, a zwitterionic bile-salt derivative, as detergent. Association of enzyme protein with the PC vesicles was verified by floatation in a discontinuous dextran gradient and by gel chromatography. An average of 35% of added HSL was incorporated into the vesicles. The vesicles were shown, by quasi-elastic light scattering and electron microscopy, to have a diameter of approximately 160 nm. The vesicle-associated HSL could be phosphorylated by cyclic AMP-dependent protein kinase. The vesicles were stable, both with regard to enzyme activity and size, for at least 4 days when stored at 4 degrees C. The preparation of detergent-free, vesicle-associated and stable HSL provides new possibilities to study some of its properties, and supports and extends the previous report (Holm, C., Fredrikson, G., and Belfrage, P., J. Biol. Chem. 261, 15659-15661, 1986) which demonstrated the amphiphilic character of HSL.
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PMID:Incorporation of hormone-sensitive lipase into phosphatidylcholine vesicles. 169 43

The localization of several GTP-binding regulatory proteins in teh apical membrane of intestinal epithelial cells has prompted us to investigate a possible role for G-proteins as modulators of apical Cl- channels. In membrane vesicles isolated from rat small intestine or human HT29-cl.19A colon carcinoma cells, the entrapment of guanosine 5'-O-(3-thiophosphate (GTP gamma S) led to a large increase in Cl- conductance, as evidenced by an increased 125I- uptake and faster SPQ quenching. The enhancement was observed in the presence, but not in the absence of the K+ ionophore valinomycin, indicating that the increased Cl- permeability is not secondary to the opening of K+ channels. The effect of GTP gamma S was counteracted by guanosine 5'-O-(2-thiophosphate (GDP beta S) and appeared to be independent of cytosolic messengers, including ATP, cAMP, and Ca2+, suggesting that protein phosphorylation and/or phospholipase C activation is not involved. Patch clamp analysis of apical membrane patches of HT29-cl.19A colonocytes revealed a GTP gamma S-activated, inwardly rectifying, anion-selective channel with a unitary conductance of 20 +/- 4 pS. No spontaneous channel openings were observed in the absence of GTP gamma S, while the open time probability (Po) increases dramatically to 0.81 +/- 0.09 upon addition with GTP gamma S. Since the electrophysiological characteristics and regulatory properties of this channel are markedly different from those of the more widely studied cAMP/protein kinase A-operated channel, we propose the existence of a separate Cl(-)-selective ion channel in the apical border of intestinal epithelial cells. Our results suggest an alternative regulatory pathway in transepithelial salt transport and a possible site for anomalous channel regulation as observed in cystic fibrosis patients.
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PMID:G-proteins mediate intestinal chloride channel activation. 170 25

A wide range of different stimuli is perceived by the intestinal epithelium. They include luminal factors, especially bacterial toxins, and agonists such as inflammatory mediators and neuro peptides, acting from the interstitial fluid surrounding the epithelial cells. It is likely that in any individual patient with diarrhoea there is a range of stimuli acting upon the epithelium. Specific receptors on the apical and basolateral membrane, activated by these stimuli, transduce the perceived signals to stimulate a series of membrane-bound enzyme systems. They in turn generate second messengers which are liberated into the cytoplasm. These include cyclic adenosine monophosphate, cyclic guanosine monophosphate, inositol triphosphate (which goes on to liberate free calcium), and diacyl glycerol. Each of these second messengers activates a different protein kinase, each of which then induces the phosphorylation of a series of cytoplasmic and membrane-bound proteins. Each of the protein kinases is likely to influence the activity of the others so that their effects are closely integrated. The final common pathways through which intestinal secretory stimuli pass involve the opening of an anion channel in the apical membrane, together with the stimulated uptake of chloride at the basolateral membrane. Anions, especially chloride and possibly bicarbonate, are then secreted into the lumen, and sodium and water passing between the cells accompany them. The net result is secretion of salt and water, which lies at the centre of a number of diarrhoeal diseases.
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PMID:Cellular basis of diarrhoea. The Croonian lecture 1989. 170 25

We report the isolation of an essential pair of Saccharomyces cerevisiae genes that encode protein kinase homologues. The two genes were independently isolated as dosage-dependent suppressors. Increased dosage of YCK1 suppressed defects caused by reduced SNF1 protein kinase activity, and increased dosage of YCK2 relieved sensitivity of wild-type cells to salt stress. The two genes function identically in the two growth assays, and loss of function of either gene alone has no discernible effect on growth. However, loss of function of both genes results in inviability. The two predicted protein products share 77% overall amino acid identity and contain sequence elements conserved among protein kinases. Partial sequence obtained for rabbit casein kinase I shares 64% identity with the two yeast gene products. Moreover, an increase in casein kinase I activity is observed in extracts from cells overexpressing YCK2. Thus YCK1 and YCK2 appear to encode casein kinase I homologues.
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PMID:Yeast casein kinase I homologues: an essential gene pair. 172 98

Platelets have been shown to possess several, different, low-molecular-mass, guanine-nucleotide-binding proteins (G-proteins) with molecular masses about 20-30 kDa. We report here that a 25-kDa G-protein copurified with the bovine platelet actin-binding protein (ABP), a cross-linker of actin filaments which is known to generate the three-dimensional network of actin. Both the G-protein and ABP were recovered in a fraction that was insoluble in Triton X-100 and were extracted in 0.6 M NaCl. Gel-filtration chromatography of the high-salt extract and rechromatography in a low-salt solution indicated that the two proteins may be associated with each other. The association of the two proteins was suggested by cosedimentation of the G-protein with the actin gel formed by actin and ABP. The amounts of the cosedimented G-protein and ABP was unaffected by guanosine-5'-O-[beta-thio]diphosphate and guanosine-5'-O-[gamma-thio]triphosphate, but the G-protein, not ABP, was partially released from the actin gel by phosphorylating ABP with cAMP-dependent protein kinase. Thus, the association of the two proteins was affected by modification of ABP, but not by modification of G-proteins. The physiological significance of the possible association of the two proteins might be that the membrane skeleton functions as a modulator of the G-protein, rather than that the G-protein modulates the function of the membrane skeleton which comprises ABP.
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PMID:Interaction of the low-molecular-mass, guanine-nucleotide-binding protein with the actin-binding protein and its modulation by the cAMP-dependent protein kinase in bovine platelets. 173 23

(1) Partially purified preparations of spinach (Spinacia oleracea L.) leaf sucrose-phosphate synthase (SPS) contain an endogenous protein kinase that phosphorylates and inactivates the enzyme with [gamma-32P]ATP. (2) The kinetic effect of phosphorylation is to alter affinities for substrates and the effector inorganic phosphate without affecting maximum velocity. (3) Two-dimensional peptide mapping of tryptic digests of in vitro labeled SPS yielded two phosphopeptides (designated sites 5 and 7). Labeling of the two sites occurred equally with time, and both correlated with inactivation. Maximum inactivation was associated with incorporation of 1.5 to 2.0 mol P/mol SPS tetramer, and about 70% of the phosphoryl groups were incorporated into one of the sites (phosphopeptide 7). (4) Phosphorylation and inactivation were strongly inhibited by NaCl, and the presence of salt alters some characteristics of the kinase reaction. In the absence of salt, the apparent Km for Mg.ATP was estimated to be 5 microM. (5) The dependence of the rate of phosphorylation on SPS concentration suggested that SPS and the protein kinase are distinct enzymes, but have some tendency to associate especially in the presence of ethylene glycol. (6) Ca2+/EGTA and polyamines have no effect on the rate of phosphorylation, whereas polycations (polylysine, polybrene and protamine) are inhibitory. (7) Of the metabolic intermediates tested, Glc 6-P inhibited phosphorylation and inactivation of the enzyme. The inhibition was not antagonized by inorganic phosphate, which suggests that Glc 6-P may be an effector of the kinase, rather than the target protein. Regulation by Glc 6-P may be of physiological significance.
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PMID:In vitro phosphorylation and inactivation of spinach leaf sucrose-phosphate synthase by an endogenous protein kinase. 182 91

High-affinity, membrane-associated inositol 1,3,4,5-tetrakisphosphate (IP4) and inositol hexakisphosphate (IP6) binding proteins were solubilized and isolated utilizing a heparin-agarose resin followed by an IP4 affinity resin. The IP6 receptor comprises a protein complex of 115-, 105-, and 50-kDa subunits, all of which comigrate under native conditions. The Kd of the receptor for IP6 is 12 nM, whereas inositol 1,3,4,5,6-pentakisphosphate (IP5), IP4, and inositol 1,4,5-trisphosphate (IP3) are 50%, 30%, and 15%, respectively, as potent. Two protein complexes copurify with the IP4 receptor fraction. A 182/123-kDa complex elutes first from the affinity column followed by a 174/84-kDa protein complex, which elutes at higher salt. Both complexes show high affinity for IP4 (Kd = 3-4 nM). IP5, IP6, and IP3 display approximately 25%, 10%, and 0.1%, respectively, the affinity of IP4. Ligand binding to IP6 and IP4 receptors is inhibited 50% by heparin at 0.1 microgram/ml. IP4 receptor proteins are stoichiometrically phosphorylated by cyclic AMP-dependent protein kinase and protein kinase C, whereas negligible phosphorylation is observed for the IP6 receptor.
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PMID:Inositol 1,3,4,5-tetrakisphosphate and inositol hexakisphosphate receptor proteins: isolation and characterization from rat brain. 184 45

Casein kinase 2 activity could be resolved into three peaks by chromatography on DEAE-Sepharose. The peak eluted at high salt concentrations (casein kinase 2b) showed molecular and kinetic properties typical of the heterotetramer composed of alpha-(or alpha'-) and beta-subunits. In contrast, the peak that was eluted at low salt concentrations (casein kinase 2a) contained no beta-subunit but a phosphorylatable protein of 49 kDa (pp49), in addition to the alpha/alpha'-subunits. The presence of alpha/alpha'/alpha"-subunits in preparations of casein kinases 2a and 2b was confirmed by immunological assays. Casein kinase 2a had low specific activity and a very high apparent Km for beta-casein. The peak eluted at intermediate ionic strength contained the alpha/alpha'-subunits and variable amounts of beta-subunit and pp49, and had kinetic properties intermediate between those of casein kinases 2a and 2b. Experiments based on heat inactivation, inhibition by low concentrations of heparin and ability to use GTP as substrate suggested that phosphorylation of pp49 was catalysed by the alpha/alpha'-subunits of casein kinase 2. No similarities were observed in the phosphopeptide maps of pp49 and beta-subunit. These results show that the alpha/alpha'-subunits of rat liver cytosol casein kinase 2 can form complexes not only with the beta-subunit but also with pp49, and that the complexes containing pp49 have a reduced affinity for the exogenous protein substrate beta-casein.
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PMID:Heterogeneity of rat liver cytosol casein kinase 2. Association between the alpha/alpha' -subunits of casein kinase 2 and the phosphorylatable protein pp49. 187 14


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