Muscles are essential for movement and heart function. Contraction and relaxation of muscles rely on the sliding of two types of filaments—the thin filament and the thick myosin filament. The thin filament is composed mainly of filamentous actin (F-actin), tropomyosin, and troponin. Additionally, several other proteins are involved in the contraction mechanism, and their malfunction can lead to diverse muscle diseases, such as cardiomyopathies. We review recent high-resolution structural data that explain the mechanism of action of muscle proteins at an unprecedented level of molecular detail. We focus on the molecular structures of the components of the thin and thick filaments and highlight the mechanisms underlying force generation through actin–myosin interactions, as well as Ca2+-dependent regulation via the dihydropyridine receptor, the ryanodine receptor, and troponin. We particularly emphasize the impact of cryo–electron microscopy and cryo–electron tomography in leading muscle research into a new era.

中文翻译：

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肌肉收缩的结构生物化学


肌肉对于运动和心脏功能至关重要。肌肉的收缩和放松依赖于两种肌丝的滑动——细肌丝和粗肌球蛋白丝。细丝主要由丝状肌动蛋白（F-肌动蛋白）、原肌球蛋白和肌钙蛋白组成。此外，其他几种蛋白质也参与收缩机制，它们的功能障碍可能导致多种肌肉疾病，例如心肌病。我们回顾了最近的高分辨率结构数据，这些数据以前所未有的分子细节水平解释了肌肉蛋白的作用机制。我们重点研究细丝和粗丝成分的分子结构，并强调通过肌动蛋白-肌球蛋白相互作用产生力的机制，以及通过二氢吡啶受体、兰尼丁受体和肌钙蛋白进行 Ca2+ 依赖性调节。我们特别强调冷冻电子显微镜和冷冻电子断层扫描在引领肌肉研究进入新时代方面的影响。