Effects of phosphorylation of bovine cardiac troponin T (TnT) by protein kinase C on the Ca(2+)-stimulated MgATPase activity of reconstituted actomyosin complex and the binding of TnT to tropomyosin(Tm)-F-actin were investigated. The Ca(2+)-stimulated MgATPase of actomyosin containing phosphorylated TnT (1.8 mol of P/mol), compared with that containing unphosphorylated TnT, was decreased by up to 48%. Phosphorylation of TnT also decreased (up to 48%) its maximum binding to Tm-F-actin, which was accompanied by a decrease (up to 3.5-fold) in its apparent binding affinity. The findings indicate that the effects of phosphorylated TnT in decreasing actomyosin MgATPase might be secondary to its decreased interactions with the other components of the thin filament, representing a new mechanism underlying the negative inotropic responses of various cardiac preparations to protein kinase C-activating phorbol esters.
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November 1992
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Research Article|
November 15 1992
Protein kinase C phosphorylation of cardiac troponin T decreases Ca2+-dependent actomyosin MgATPase activity and troponin T binding to tropomyosin-F-actin complex
T A Noland, Jr;
T A Noland, Jr
1Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, U.S.A.
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J F Kuo
J F Kuo
1Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1992 The Biochemical Society, London
1992
Biochem J (1992) 288 (1): 123–129.
Citation
T A Noland, J F Kuo; Protein kinase C phosphorylation of cardiac troponin T decreases Ca2+-dependent actomyosin MgATPase activity and troponin T binding to tropomyosin-F-actin complex. Biochem J 15 November 1992; 288 (1): 123–129. doi: https://doi.org/10.1042/bj2880123
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