Troponin C - troponin I interactions and molecular signalling in cardiac myofilaments.
This chapter describes a current perception of the molecular interactions regulating myofilament activity in heart cells. The focus is on the interaction between troponin-C (TnC), the Ca(2+)-receptor and troponin I (TnI), an inhibitory protein. It is this interaction that appears to form a molecular switch that turns on the thin filament. It will be seen that control of the actin-myosin reaction is not only through Ca(2+)-binding to TnC, but also through steric, cooperative and allosteric processes involving all of the main myofilament proteins-actin, myosin, tropomyosin (Tm), troponin T (TnT), TnC, and TnI. The process is modulated by covalent and non-covalent mechanisms. The process is altered in diverse myopathies and pathologies of the heart and is a target for pharmacological manipulation by a new class of inotropic agents, the "Ca(2+)-sensitizers".
Department of Physiology & Biophysics, College of Medicine, University of Illinois-Chicago 60612-7342, USA.
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D008841:Actin Cytoskeleton / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D014336:Troponin / Q000378:metabolism*; D019209:Troponin C; D019210:Troponin I
D014336:Troponin; D019209:Troponin C; D019210:Troponin I; D002118:Calcium