PDF(Pubmed)
Abstract：
Time-resolved X-ray diffraction of isolated fast-twitch muscles of mice was used to show how structural changes in the myosin-containing thick filaments contribute to the regulation of muscle contraction, extending the previous focus on regulation by the actin-containing thin filaments. This study shows that muscle activation involves the following sequence of structural changes: thin filament activation, disruption of the helical array of myosin motors characteristic of resting muscle, release of myosin motor domains from the folded conformation on the filament backbone, and actin attachment. Physiological force generation in the \'twitch\' response of skeletal muscle to single action potential stimulation is limited by incomplete activation of the thick filament and the rapid inactivation of both filaments. Muscle relaxation after repetitive stimulation is accompanied by a complete recovery of the folded motor conformation on the filament backbone but by incomplete reformation of the helical array, revealing a structural basis for post-tetanic potentiation in isolated muscles.
摘要：
小鼠离体快速抽搐肌肉的时间分辨X射线衍射用于显示含肌球蛋白的粗丝的结构变化如何促进肌肉收缩的调节，扩展了以前对含肌动蛋白的细丝调节的关注。这项研究表明，肌肉激活涉及以下序列的结构变化：细丝激活，破坏静息肌肉的肌球蛋白马达的螺旋阵列，肌球蛋白运动结构域从细丝主链上折叠的构象中释放，和肌动蛋白附件。骨骼肌对单动作电位刺激的“抽搐”反应中的生理力产生受到粗丝不完全激活和双丝快速失活的限制。重复刺激后的肌肉松弛伴随着细丝主链上折叠的运动构象的完全恢复，但螺旋阵列的不完全重整，揭示了孤立肌肉强直后增强的结构基础。
