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

横纹肌肌节的伸展可引起横纹肌更高的收缩活动。肌节组织良好的精细结构是导致这种牵张激活现象的原因，但其具体机制尚不清楚。发展二维X射线衍射技术，我们发现拉伸诱导肌球蛋白头部从粗丝骨架向细丝上相邻的肌动蛋白分子伸出，从而促进肌球蛋白头部和肌动蛋白分子之间收缩横桥的形成。

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.