TnT1 increased the apparent cooperative unit size of Tm.actin from 6 to 9, while TnT2IC reduced the S1-binding rate constant 2-3-fold in the absence of Ca2+.
The N- and C-terminal regions of troponin T act independently to modulate myosin S1 binding to the tropomyosin-actin thin filament, contributing to muscle regulation.
Mild proteolytic cleavage of the troponin complex yields TnT1, the N-terminal fragment of troponin T, and TnT2IC, a complex of the C-terminal fragment of troponin T (TnT2) with troponin I (TnI) and troponin C (TnC) [Morris, E. P., i.e., in the absence of Ca2+, kapp is reduced 2-3-fold by both TnT2IC and whole troponin. Thus, the N- and C-terminal regions of TnT appear to act independently in modulating effects of S1 binding to the Tm.actin thin filament that are important in regulation.
Schaertl et al. (Tue,) reported a other. TnT1 and TnT2IC vs. Whole troponin was evaluated on Cooperativity and S1-binding rate constant to Tm.actin. TnT1 increased the apparent cooperative unit size of Tm.actin from 6 to 9, while TnT2IC reduced the S1-binding rate constant 2-3-fold in the absence of Ca2+.