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dc.contributor.authorWalsh, M.-
dc.contributor.authorSusnjar, M.-
dc.contributor.authorDeng, J.-
dc.contributor.authorSutherland, C.-
dc.contributor.authorKiss, E.-
dc.contributor.authorWilson, D.-
dc.contributor.editorGreg Moorhead-
dc.identifier.citationProtein Phosphatase Protocols, 2007 / Greg Moorhead (ed./s), vol.365, pp.209-224-
dc.description© 2007 Humana Press-
dc.description.abstractCPI-17 is a cytosolic protein of 17 kDa that becomes a potent inhibitor of certain type 1 protein serine/threonine phosphatases, including smooth muscle myosin light-chain phosphatase (MLCP), when phosphorylated at Thr38. Several protein kinases are capable of phosphorylating CPI-17 at this site in vitro; however, in intact tissue, compelling evidence only exists for phosphorylation by protein kinase C (PKC). Agonist-induced activation of heterotrimeric G proteins of the Gq/11 family via seven-transmembrane domain-containing, G protein-coupled receptors results in phospholipase Cbeta-mediated hydrolysis of membrane phosphatidylinositol 4,5-bisphosphate to generate inositol 1,4,5-trisphosphate (IP3) and 1,2-diacylglycerol (DAG). IP3 triggers Ca2+ release from the sarcoplasmic reticulum. DAG and Ca2+ together activate classical isoforms of PKC, and DAG activates novel PKC isoforms without a requirement for Ca2+. Activated PKC phosphorylates CPI-17 at Thr38, enhancing its potency of inhibition of MLCP approx 1000-fold. The myosin light-chain kinase (MLCK):MLCP activity ratio is thereby increased at the prevailing cytosolic free-Ca2+ concentration ([Ca2+]i), resulting in an increase in phosphorylation of the 20-kDa light chains of myosin II (LC20) catalyzed by Ca2+- and calmodulin-dependent MLCK and contraction of the smooth muscle. Physiologically, this mechanism can account for some instances of Ca2+ sensitization of smooth muscle contraction (i.e., an increase in force in response to agonist stimulation without a change in [Ca2+]i).-
dc.description.statementofresponsibilityMichael P. Walsh, Marija Susnjar, Jingti Deng, Cindy Sutherland, Enikö Kiss, and Divid P. Wilson-
dc.publisherHumana Press-
dc.relation.ispartofseriesMethods in Molecular Biology ; 367-
dc.subjectMyosin-Light-Chain Phosphatase-
dc.subjectMyosin-Light-Chain Kinase-
dc.subjectProtein Kinase C-
dc.subjectPhosphoprotein Phosphatases-
dc.titlePhosphorylation of the Protein Phosphatase Type 1 Inhibitor Protein CPI-17 by Protein Kinase C-
dc.typeBook chapter-
dc.publisher.placeTotowa, NJ-
Appears in Collections:Aurora harvest 6
Molecular and Biomedical Science publications

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