Stretch of muscle sarcomere induces protrusion of myosinheads toward actin so as to facilitate formation of contractile cross-bridges.

横纹肌肌节的拉伸引起横纹肌较高的收缩活性。肌节组织良好的精细结构与这种拉伸激活现象有关，但其具体机制尚未阐明。利用二维x射线衍射技术，我们发现拉伸诱导肌凝蛋白头从粗纤维骨架向细纤维上邻近的肌动蛋白分子突出，从而促进肌凝蛋白头与肌动蛋白分子之间形成可收缩的交叉桥。

Stretch of sarcomeres of striated muscle induces higher contractile activity in striated muscle. Well organized fine structure of sarcomere is responsible to this stretch activation phenomenon, but its detailed mechanism has not been elucidated. Developing two-dimensional x-ray diffraction techniques, we found that stretch induces protrusion of myosin heads out of the thick filament backbone toward the neighboring actin molecules on thin filament so as to facilitate formation of contractile cross-bridges between myosin heads and actin molecules.