Effects of sarcomere length and Ca(2+) binding on h reactivity of myofilament bound troponin C in porcine skinned cardiac muscle fibers.
Length dependence of cardiac Ca(2+) activation is an essential component of the Frank-Starling relation. The aim of this study is to examine the length effects on the Ca(2+)-induced conformational changes of filament-bound cTnC in skinned cardiac muscle fibers. The two cysteine residues (Cys-35 and Cys-84) in the regulatory domain of cTnC allow for the attachment of conformational probes to this region. Their incorporation with the fluorescent probe, 7-diethylamino-3-[4'-maleimidylphenyl]-4-methylcoumarin (CPM), was used to determine the varying cTnC conformations in cardiac fibers. The data obtained show that the length-dependent Ca(2+)-mediated conformational changes require strong-binding cross-bridges for cardiac activation.
Liou
Y M
YM
Department of Zoology, Institute of Biochemistry, National Chung-Hsing University, Taichung, 402, Taiwan. ymlion@dragon.nchu.edu.tw
D008841:Actin Cytoskeleton / Q000502:physiology / Q000648:ultrastructure*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006321:Heart / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology / Q000648:ultrastructure; D009206:Myocardium / Q000648:ultrastructure*; D011487:Protein Conformation; D012518:Sarcomeres / Q000648:ultrastructure*; D013552:Swine; D019209:Troponin C / Q000494:pharmacology*
D019209:Troponin C; D002118:Calcium