Holmes K C, Goody R S
Ciba Found Symp. 1983;93:139-55. doi: 10.1002/9780470720752.ch8.
Muscle contraction takes place by the cyclic interaction of two-stranded helical actin filaments with protuberances from the myosin filaments known as cross-bridges. The nature of the contractile process demands that the myosin cross-bridge be highly polymorphic. Biochemical evidence points to the cross-bridge having a domain structure such that contraction may be a manifestation of the rearrangement of these subunits. An essential step in contraction may be the initial binding of a small hinged domain of the cross-bridge (the 'nose-cone') to actin, followed by a series of changes ending in the formation of a second union (the rigor bond) with an actin monomer in the neighbouring strand of the actin helix.
肌肉收缩通过双链螺旋状肌动蛋白丝与肌球蛋白丝上称为横桥的突起的循环相互作用发生。收缩过程的性质要求肌球蛋白横桥具有高度多态性。生化证据表明横桥具有结构域结构，使得收缩可能是这些亚基重排的表现。收缩的一个关键步骤可能是横桥的一个小铰链结构域（“鼻锥”）与肌动蛋白的初始结合，随后是一系列变化，最终与肌动蛋白螺旋相邻链中的肌动蛋白单体形成第二个结合（强直键）。
