Effect of troponin C on the cooperativity in Ca2+ activation of cardiac muscle.
This study describes the effects of exchanging native cardiac troponin C (CTnC) from the right ventricular muscle of Syrian hamster for purified skeletal (S) TnC from fast twitch muscles in triggering cardiac contraction. Ca2+ sensitivity of the myocardium became decreased with STnC to 62% of the original value with CTnC. Furthermore, the slope of the pCa-force curve of cardiac muscle was found to be increased with STnC. The results show that the TnC moiety, as part of the switching mechanism during activation, also regulates thin-filament cooperativity in muscle. Modifications in both the Ca2+ sensitivity and cooperativity are associated with alterations in the primary structure of TnC.
Gulati
J
J
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461.
Scordilis
S
S
Babu
A
A
D000818:Animals; D002118:Calcium / Q000502:physiology*; D006224:Cricetinae; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D046911:Macromolecular Substances; D009200:Myocardial Contraction; D013329:Structure-Activity Relationship; D014336:Troponin / Q000502:physiology*; D019209:Troponin C
D046911:Macromolecular Substances; D014336:Troponin; D019209:Troponin C; D002118:Calcium