Olah G A, Trewhella J
Chemical Science and Technology Division, Los Alamos National Laboratory, New Mexico 87545.
Biochemistry. 1994 Nov 1;33(43):12800-6. doi: 10.1021/bi00209a011.
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.
我们在此报告一种使用蒙特卡罗建模方法，基于小角X射线和中子散射数据得出的4Ca2+·肌钙蛋白C·肌钙蛋白I的模型结构。在该模型中，肌钙蛋白I呈现为螺旋结构，环绕着4Ca2+·肌钙蛋白C，后者采用类似于肌钙蛋白C晶体结构中观察到的伸展哑铃构象。肌钙蛋白I螺旋具有近似α-螺旋的尺寸，并穿过肌钙蛋白C每个球状结构域中的疏水“杯状”区域。该模型与先前发表的关于肌钙蛋白C和肌钙蛋白I之间相互作用的大量生化数据一致，并表明调节肌肉收缩/舒张周期的Ca(2+)敏感开关的分子机制涉及通过肌钙蛋白I的中央螺旋区域传递的信号。
