在ADP释放时,光滑肌肉肌肉素的35-A运动会释放ADP
M Whittaker1, E M Wilson-Kubalek, J E Smith
1Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA.
Nature
|December 14, 1995
概括
肌酸二号运动蛋白通过actin相互作用产生力. 一个刚性轻链域充当杆臂,在肌肉收缩过程中将小型运动域的变化转化为大型35安格斯特罗姆的步骤.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 肌肉生理学 肌肉生理学
背景情况:
- 肌酸II运动蛋白对于肌肉收缩至关重要,它与F-actin丝相互作用.
- 肌肉蛋白的电力冲击的机制,涉及ATP水解,尚未完全理解.
- 之前的研究表明,在跨桥自行车行驶期间,肌肉素头部 (S1) 在actin上的运动有限.
研究的目的:
- 为了阐明肌肉素电动冲击机制的结构基础.
- 为了研究肌S1域和轻链结合域在力产生中的作用.
- 为了确定ATP水解和actin结合过程中肌肉素的构造变化.
主要方法:
- 三维 (3D) 电子显微镜 (cryo-EM) 用于绘制S1-装饰的F-actin结构.
- 在MgADP的存在和缺席下确定结构,以捕获肌电机的不同状态.
- 进行了详细的结构分析,比较了肌酶电机域和轻链结合域的方向.
主要成果:
- 肌蛋白运动域结构在MgADP结合和未结合状态之间在很大程度上保持一致.
- 在轻链结合领域观察到显著的定向差异.
- 轻链结合域作为一个刚性杆臂,旋转大约23度.
- 这种旋转会导致大约35安格斯特罗姆的实质性步骤大小.
结论:
- 肌的动力冲击主要是由轻链结合域的旋转驱动的,而不是电机领域的大型形状变化.
- 核酸介导的肌运动域的构造变化被轻链域放大,产生大移动步骤.
- 这种杆臂机制解释了肌肉素如何产生有效的力量来进行肌肉收缩和细胞运动.
相关概念视频
01:26Cross-bridge Cycle
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01:16Actin and Myosin in Muscle Contraction
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01:43The Movement of Organelles and Vesicles
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01:18Role of Myosin in Cell Migration
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01:20Excitation-Contraction Coupling in Skeletal Muscles
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01:25Smooth Muscle Contraction
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