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)

The catalytic subunit of cyclic AMP-dependent protein kinase (from rabbit skeletal muscle; ATP:protein phosphotransferase, EC 2.7.1.37) was found to be irreversibly inactivated by chloromethyl ketone derivatives of lysine and phenylalanine, chemical reagents originally designed for labeling the active sites of the proteolytic enzymes trypsin and chymotrypsin. This inactivation was shown to occur at pH 7.5 and 22 degrees C, conditions under which chemically related alkylating reagents such as chloroacetamide and chloroacetic acid (which do not possess the amino acid side chain) fail to inactivate the enzyme. In the case of the chloromethyl ketone derivative of N alpha-tosyl-L-lysine, the enzyme could be protected by its nucleotide substrate (MgATP), by one of its protein substrates (histone H2b), and by its regulatory subunit which, upon binding, shields the active site of the catalytic subunit. Differential labeling experiments, together with kinetic studies of the rates of modification of the sulfhydryl groups in the enzyme before and after inactivation with the chloromethyl ketone, suggest that the loss of activity is associated with one (kinetically characterized) sulfhydryl group present either at the active site of the enzyme or at a site intimately associated with it. The general implications of these results regarding the interpretation of affinity labeling experiments carried out in complex mixtures of proteins or under in vivo conditions are discussed.
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PMID:Affinity labeling of the catalytic subunit of cyclic AMP-dependent protein kinase by N alpha-tosyl-L-lysine chloromethyl ketone. 22 53

Bovine heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) was phosphorylated by incubation with [gamma-32P]MgATP and cyclic AMP-dependent protein kinase (PKA) or protein kinase C (PKC). After digestion with chymotrypsin, the phosphorylation sites for the two protein kinases were identified by peptide mapping, and microsequencing. Evidence for new phosphorylation sites for PKA (Ser-483) and PKC (Ser-84 and Ser-466) was obtained.
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PMID:Evidence for new phosphorylation sites for protein kinase C and cyclic AMP-dependent protein kinase in bovine heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase. 132 69

Plasmin inhibited the biosynthesis of tissue-type plasminogen activator (tPA) antigen by human umbilical vein endothelial cells (HUVEC) in a dose-dependent manner. The amount of tPA antigen found in the 24-h conditioned medium of cells treated with 100 nM plasmin for 1 h was 20-30% of that in the control group. However, in contrast to tPA, such treatment led to a 3-fold increase in plasminogen activator inhibitor (PAI) activity, whereas the amount of PAI type 1 antigen was unchanged. The effects of plasmin on HUVEC were binding- and catalytic activity-dependent and were specifically blocked by epsilon-aminocaproic acid. Microplasmin, which has no kringle domains, was less effective in reducing tPA antigen biosynthesis or enhancing PAI activity in HUVEC. Kringle domains of plasmin affected neither tPA antigen nor PAI activity of the cells. Other proteases including chymotrypsin, trypsin, and collagenase at comparable concentrations did not have a significant effect on the biosynthesis of tPA antigen or PAI activity of HUVEC. Thrombin stimulated the biosynthesis of tPA and PAI-1 antigens by HUVEC. Thrombin also stimulated an increase in the protein kinase activity in HUVEC, whereas plasmin inhibited the protein kinase activity of the cells. It is possible that plasmin regulates the biosynthesis of tPA in HUVEC through the signal transduction pathway involving protein kinase.
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PMID:Plasmin and the regulation of tissue-type plasminogen activator biosynthesis in human endothelial cells. 138 68

The mitochondrial kinases responsible for the phosphorylation and inactivation of rat heart pyruvate dehydrogenase complex and the rat liver and heart branched-chain alpha-ketoacid dehydrogenase complexes have been purified to homogeneity. The branched-chain alpha-ketoacid dehydrogenase kinase is composed of one subunit with a molecular weight of 44 kDa; pyruvate dehydrogenase kinase has two subunits with molecular weights of 48 (alpha) and 45 kDa (beta). Proteolysis maps of branched-chain alpha-ketoacid dehydrogenase kinase and the two subunits of pyruvate dehydrogenase kinase are different, suggesting that all subunits are different entities. The alpha subunit of the rat heart pyruvate dehydrogenase kinase was selectively cleaved by chymotrypsin with concomitant loss of kinase activity, as previously shown for the bovine kidney enzyme, suggesting that the catalytic activity of pyruvate dehydrogenase kinase resides in this subunit. Polyclonal antibodies against branched-chain alpha-ketoacid dehydrogenase kinase, purified by an epitope selection method, bound only to the 44 kDa polypeptide of the branched-chain alpha-ketoacid dehydrogenase complex, substantiating that the 44 kDa protein corresponds to the kinase for this complex. Both kinases exhibited strong substrate specificity toward their respective complexes and would not inactivate heterologous complexes. The kinases possessed slightly different substrate specificities toward histones. Phosphorylation and inactivation of the branched-chain alpha-ketoacid dehydrogenase complex by its purified kinase was inhibited by alpha-chloroisocaproate and dichloroacetate, established inhibitors of the phosphorylation of the complex. cDNAs encoding the branched-chain alpha-ketoacid dehydrogenase kinase have been isolated from rat heart and rat liver lambda gt11 libraries. This represents the first successful cloning of a mitochondrial protein kinase. Preliminary data suggest that two different isoforms of the kinase may exist in different ratios in various tissues. No evidence was found for induction of the branched-chain alpha-ketoacid dehydrogenase complex nor its kinase by clofibric acid. Rather, clofibric acid is a potent inhibitor of the activity of the branched-chain alpha-ketoacid dehydrogenase kinase and this may be the molecular mechanism responsible for the myotonic effects of clofibric acid in man.
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PMID:Purification, characterization, regulation and molecular cloning of mitochondrial protein kinases. 149 22

Casein kinase I activity is present in cells as a cytosolic and a membrane-bound enzyme. Previously, the erythroid membrane-bound casein kinase I was shown to associate with purified integral membrane proteins; this association and protein kinase activity was regulated by phosphatidylinositol 4,5-bisphosphate (PIP2) (Bazenet, C.E., Brockman, J.L., Lewis, D., Chan, C., and Anderson, R.A. (1990) J. Biol. Chem. 265, 7369-7376). Here we show that both the membrane-bound and the cytosolic casein kinase interact with native membranes and that this interaction is regulated by the membrane content of PIP2. On native membranes, casein kinase I activity is potently inhibited by small increases (10-20%) in the membrane content of either exogenously added or intrinsic PIP2. However, the majority of the intrinsic content of PIP2 in isolated membranes does not inhibit casein kinase, suggesting that this PIP2 is not accessible. Regulation of the casein kinases on membranes is sensitive to detergents and to chymotrypsin treatment of membranes.
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PMID:Casein kinase I is regulated by phosphatidylinositol 4,5-bisphosphate in native membranes. 184 28

Several lines of evidence have demonstrated conclusively the presence of cAMP-dependent protein kinase (ecto-RC) activity on the external surface of goat cauda-epididymal intact spermatozoa. The intact-cell ecto-kinase that caused transfer of the terminal phosphate of exogenous ATP to the serine and threonine residues of exogenous histone was specifically activated by cAMP. As well, the ecto-kinase caused phosphorylation of the synthetic peptide Kemptide. The isolated spermatozoa, before or after incubation with reaction mixture for ecto-kinase assays, were approximately 99.5% viable, as shown by the analyses of ethidium bromide fluorescence and the cytosolic marker enzymes lactic dehydrogenase and 3-phosphoglycerate kinase. The ecto-kinase activity was not due to contamination of epididymal plasma and damaged cells or to protein kinase that may have leaked from the cells. There was little uptake of ATP and histone by the cells. The intact-cell kinase activity was strongly (80-90%) inhibited by treatment with membrane nonpenetrating surface probes: p-chloromercuriphenylsulfonic acid (2 microM), diazonium salt of sulfanilic acid (DSS, 0.5 mM), and proteases such as trypsin, chymotrypsin, and pronase (each 125 micrograms/mL). Disruption of sperm plasma membrane by sonication or Triton X-100 (0.2%) caused about a fivefold increase of the intact sperm kinase activity. Highly purified sperm plasma membrane (PM) possessed ecto-kinase activity that was resolved into type I and II kinases by DEAE-cellulose chromatography, the type I isoenzyme being the major (approximately 70%) enzymic species. Treatment of the intact spermatozoa with DSS prior to isolation of PM caused a marked loss of the activities of both the isoenzymes, indicating thereby the "ecto" nature of the PM-bound type I and II kinases. Preparations of vigorously forward-motile spermatozoa with 100% intactness had approximately fourfold higher specific activity of the ecto-kinase than the "composite" cells from which the former cells were isolated. However, the profiles of the type I and II ecto-kinases of the composite, as well as forward-motile spermatozoa, were nearly identical. The data are consistent with the view that ecto-kinases may have role in the regulation of flagellar motility.
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PMID:Type I and II cAMP-dependent ecto-protein kinases in goat epididymal spermatozoa and their enriched activities in forward-motile spermatozoa. 216 Aug 33

We have examined the synthesis of the protease inhibitors alpha 1-antitrypsin (alpha 1-AT) and alpha 1-antichymotrypsin (alpha 1-ACHY) by variants of the MCF-7 human breast cancer cell line. Spent medium from MCF-7 203P cells, grown in the absence of serum, was found to contain immunoreactive alpha 1-AT and alpha 1-ACHY by Western blotting. In the presence of 10(-8) M estradiol, levels of both inhibitors were increased 3- to 6-fold. Incubation of spent medium with [125I]trypsin or [125I]chymotrypsin resulted in the formation of stable 75- and 90-kDa complexes identical to the complexes formed between these proteases and the protease inhibitors in plasma, showing the release of active protease inhibitors by MCF-7 cells in culture. Immunoprecipitation of 35S-labeled proteins from the medium of cells grown in the presence of [35S]methionine yielded comparable results, confirming hormonally sensitive synthesis of both protease inhibitors. Northern blot analysis suggests that stimulation of estradiol occurs at the level of transcription. Tetradecanoyl phorbol acetate (50 ng/ml) also stimulated alpha 1-AT and alpha 1-ACHY synthesis 2- to 4-fold, suggesting the involvement of protein kinase-C. Comparison studies with MCF-7 cell sublines ML, BK, 203P, and 300P (a variant spontaneously appearing after 100 passages of 203P) show a wide variation in synthesis of alpha 1-AT and alpha 1-ACHY proteins; sublines 203P and 300P synthesize both inhibitors, the ML subline synthesizes detectable amounts only of alpha 1-ACHY, while no detectable synthesis of either inhibitor was seen in the BK subline. Similar results were obtained for protease inhibitor mRNA transcription by Northern blotting, although low levels of alpha 1-AT mRNA transcription by the ML subline and of alpha 1-AT and alpha 1-ACHY mRNA transcription by the BK subline could be detected.
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PMID:Regulation of antitrypsin and antichymotrypsin synthesis by MCF-7 breast cancer cell sublines. 220 35

A plasmalemmal Na(+)-Ca2+ exchange mechanism is an important electrogenic determinant of contractility in cardiac cells. As in other cell types, calcium influx by Na(+)-Ca2+ exchange is secondarily activated by cytoplasmic calcium and probably ATP, but these modulatory mechanisms are either absent or altered in isolated cardiac sarcolemmal vesicles. Involvement of a calcium-dependent protein kinase in exchange regulation has been suggested but not verified. Here I describe measurements of outward Na(+)-Ca2+ exchange current, corresponding to calcium influx, in giant excised sarcolemmal patches from guinea pig myocytes. The exchange current is stimulated by both calcium and Mg-ATP from the cytoplasmic face, evidently through separate mechanisms. Activation by cytoplasmic calcium takes place within seconds, is reversible, and does not require ATP. Stimulation by Mg-ATP reverses only slowly over greater than 10 min, or not at all. Unexpectedly, a substantial decrease in exchange current occurs during activation by cytoplasmic sodium, which seems to reflect an inactivation process rather than ion concentration changes or a 'first pass' exchange cycle. This apparent inactivation, and the modulations by cytoplasmic calcium and Mg-ATP, are all abolished by brief treatment of the cytoplasmic surface with chymotrypsin, leaving the exchanger in a maintained state of high activity. Therefore, limited proteolysis deregulates Na(+)-Ca2+ exchange and could contribute to the loss of secondary regulation of the exchange in isolated sarcolemmal vesicles.
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PMID:Regulation and deregulation of cardiac Na(+)-Ca2+ exchange in giant excised sarcolemmal membrane patches. 231 60

The two forms of clathrin light chains (LCA and LCB) or clathrin-associated proteins (CAP1 and CAP2) have presented an immunochemical paradox. Biochemically similar, both possess two known functional parameters: binding the clathrin heavy chain and mediating the action of an uncoating ATPase. All previously reported anti-CAP mAbs, however, react specifically with only CAP1 (Brodsky, F. M., 1985, J. Cell Biol., 101:2047-2054; Kirchhausen, T., S. C. Harrison, P. Parham, and F. M. Brodsky, 1983, Proc. Natl. Acad. Sci. USA, 80:2481-2485). Four new anti-CAP mAbs are reported here: two, C-7H12 and C-6C1, react with both forms; two others, C-10B2 and C-4E5, react only with the lower form. Sandwich ELISAs indicated that C-10B2, C-4E5, C-6C1, and C-7H12 react with distinct epitopes. Monoclonal antibodies C-10B2 and C-4E5 immunoprecipitate clathrin-coated vesicles (CCVs) and react with CAP2 epitopes accessible to chymotrypsin on the vesicle. These mAbs inhibit phosphorylation of CAP2 by endogenous CCV casein kinase II. In contrast, C-6C1 and C-7H12 react with epitopes that are relatively insensitive to chymotrypsin. CAP peptide fragments containing these epitopes remain bound to reassembled cages or CCVs after digestion. Immunoprecipitation and ELISAs demonstrate that C-7H12 and C-6C1 react with unbound CAPs but not with CAPs bound to triskelions or CCVs. The data indicate that the CAPs consist of at least two discernible structural domains: a nonconserved, accessible domain that is relevant to the phosphorylation of CAP2 and a conserved, inaccessible domain that mediates the binding of CAPs to CCVs.
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PMID:Mapping two functional domains of clathrin light chains with monoclonal antibodies. 243 41

ARPP-21 (cAMP-regulated phosphoprotein, Mr = 21,000 as determined by SDS-PAGE) is a major cytosolic substrate for cAMP-stimulated protein phosphorylation in dopamine-innervated regions of the rat CNS. It has recently been purified to homogeneity from bovine caudate nucleus and characterized (Hemmings and Greengard, 1989). ARPP-21 is isolated as 2 isoforms, ARPP-21A and ARPP-21B. The amino acid sequence of purified bovine ARPP-21B has now been determined by gas-phase sequencing. The S-14C-carboxymethylated protein was subjected to enzymatic cleavage with trypsin, chymotrypsin, subtilisin, and endoproteinase Lys-C. The resulting peptides were purified by high-performance liquid chromatography, and selected peptides were subjected to amino acid analysis and/or amino acid sequencing by automated Edman degradation. ARPP-21B consists of a single NH2-terminal blocked polypeptide chain of 88 residues, with a calculated molecular mass of 9561 Da, including an NH2-terminal acetyl group inferred by deblocking with an acylaminopeptidase. This molecular mass is significantly lower than earlier estimates based on SDS-PAGE or hydrodynamic measurements. The seryl residue phosphorylated by cAMP-dependent protein kinase (Hemmings et al., 1989) is located at position 55. The molecule contains 1 cysteinyl residue, at position 71, and contains no methionyl, tyrosyl, phenylalanyl, tryptophanyl, or histidinyl residues. Determination of the primary structure of ARPP-21, one of several phosphoproteins localized to dopaminoceptive neurons in the basal ganglia, provides a framework for further investigations into the molecular mechanisms involved in dopaminergic neurotransmission.
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PMID:ARPP-21, a cyclic AMP-regulated phosphoprotein enriched in dopamine-innervated brain regions. I. Amino acid sequence of ARPP-21B from bovine caudate nucleus. 255 36


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