A model structure of the muscle protein complex 4Ca2+.troponin C.troponin I derived from small-angle scattering data: implications for regulation.
A model structure of the muscle protein complex 4Ca2+.troponin C.troponin I derived from small-angle scattering data: implications for regulation.
复制标题
源自小角散射数据的肌肉蛋白复合物 4Ca2 .肌钙蛋白 C.肌钙蛋白 I 的模型结构：对调节的影响。
DOI：
10.1021/bi00209a011
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Trewhella,J
中科院分区：
文献类型：
--
作者：
Olah,GA;Trewhella,J
1994年8月17日收到的修订版Mandalpt ®摘要：我们在这里报告了一个4Ca 2 +* 肌钙蛋白C-肌钙蛋白I的模型结构，该模型结构使用Monte Carlo建模方法从小角度X射线和中子散射数据中获得。在该模型中，肌钙蛋白I表现为缠绕在4Ca 2 +-肌钙蛋白C周围的螺旋结构，其采用与肌钙蛋白C晶体结构中观察到的类似的延伸哑铃构象。肌钙蛋白I螺旋具有a-螺旋的近似尺寸，并缠绕通过肌钙蛋白C的每个球状结构域中的疏水性“杯”。该模型与先前发表的关于肌钙蛋白C和肌钙蛋白I之间相互作用的生物化学数据一致，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。在肌肉收缩的滑动细丝模型中，交错的粗细丝和细丝彼此移动，导致收缩和松弛。粗肌丝由肌球蛋白组成，而细肌丝由肌动蛋白单体的螺旋组装而成，其中原肌球蛋白在肌动蛋白螺旋的凹槽中首尾聚合，并且每个原肌球蛋白结合到一个肌钙蛋白。收缩力被认为是当肌球蛋白头SI周期性地附着和脱离肌动蛋白单体上的特定位点时产生的，从而在周期的附着阶段的某个时间发生由肌动蛋白-SI-肌球蛋白ATP酶活性驱动的动力冲程。肌钙蛋白和原肌球蛋白形成调节肌球蛋白和肌动蛋白之间相互作用的Ca 2+敏感开关[莱亚维斯和Germinal（1984）以及Zot和Potter（1987）综述]。肌钙蛋白有三个亚基：结合Ca 2+的肌钙蛋白C（TnC）1，抑制肌动蛋白-S1-肌球蛋白ATP酶活性的肌钙蛋白I（TnI），和将肌钙蛋白结合到原肌球蛋白的肌钙蛋白T（TnT）。x射线
Revised Manuscript Received August 17, 1994® abstract: 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 a-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 Ca2+-sensitive switchthat regulates the muscle contraction/relaxation cycle involves a signal transmitted via the central spiral region of troponin I.In the sliding filament model of muscle contraction, interdigitating thick and thin filaments move past each other, resulting in contraction and relaxation. The thick filaments are composed of myosin, while the thin filaments are made from a helical assembly of actin monomers with tropomyosin polymerized head to tail in the grooves of the actin helix, and each tropomyosin bound to one troponin. The contractile force is thought to be generated when the myosin heads, SI, cyclically attach and detach from specific sites on the actin monomers, whereby a power stroke, driven by actin-Sl-myosin ATPase activity, occurs sometime during the attach-ment phase of the cycle. Troponin and tropomyosin form a Ca2+-sensitive switch which regulates the interactions between myosin and actin [reviewed by Lea vis and Gergely (1984) and Zot and Potter (1987)]. Troponin has three subunits: troponin C (TnC) 1which binds Ca2+, troponin I (Tnl) which inhibits the actin-Sl-myosin ATPase activity, and troponin T (TnT) which binds troponin to tropomyosin. The X-ray