A Monte Carlo model derived from small-angle scattering data suggests troponin I forms a spiral structure wrapping around troponin C, providing a mechanism for the Ca2+-sensitive regulatory switch.
Provides a structural model for the troponin C-troponin I complex, suggesting a mechanism for the calcium-sensitive switch in muscle contraction.
We report here a model structure for 4Ca2+.troponin C.troponin I derived from small-angle X-ray and neutron scattering data using a Monte Carlo modeling method. In this model, troponin I appears as a spiral structure that wraps around 4Ca2+.troponin C which adopts an extended dumbbell conformation similar to that observed in the crystal structures of troponin C. The troponin I spiral has the approximate dimensions of an alpha-helix and winds through the hydrophobic "cups" in each globular domain of troponin C. The model is consistent with a body of previously published biochemical data on the interactions between troponin C and troponin I, and suggests the molecular mechanism for the Ca(2+)-sensitive switch that regulates the muscle contraction/relaxation cycle involves a signal transmitted via the central spiral region of troponin I.
Olah et al. (Sat,) reported a other. A Monte Carlo model derived from small-angle scattering data suggests troponin I forms a spiral structure wrapping around troponin C, providing a mechanism for the Ca2+-sensitive regulatory switch.