Rasmussen H, Takuwa Y, Park S
FASEB J. 1987 Sep;1(3):177-85.
The cellular and molecular mechanisms underlying smooth muscle contraction are reviewed in the light of recent studies of smooth muscle ultrastructure and of the role of polyphosphoinositide turnover and protein kinase C function in smooth muscle contraction. A new model of smooth muscle contraction is proposed that differs radically from accepted views, particularly the latch bridge hypothesis, in terms of both Ca2+ messenger function and the molecular events underlying this process. A coordinate fibrillar domain model of contraction is proposed in which the initial and sustained phases of contraction are mediated by different cellular and molecular events. The initial phase of response is mediated by a rise in [Ca2+]c and the resulting calmodulin-dependent activation of both myosin light chain kinase and the dissociation of caldesmon from the actin-caldesmon-tropomyosin-myosin fibrillar domain. These events lead to an interaction between actin and the phosphorylated light chains of myosin just as in previous models. However, this initial phase is followed by a sustained phase in which a rise in [Ca2+]sm stimulates the plasma membrane-associated, Ca2+-sensitive form of protein kinase C that results in the phosphorylation of both structural and regulatory components of the filamin-actin-desmin fibrillar domain. These events underlie the tonic phase of contraction.
根据平滑肌超微结构以及多磷酸肌醇代谢和蛋白激酶C功能在平滑肌收缩中作用的最新研究，对平滑肌收缩的细胞和分子机制进行了综述。提出了一种平滑肌收缩的新模型，该模型在Ca2+信使功能以及此过程背后的分子事件方面，与公认观点，特别是闩锁桥假说有根本不同。提出了一种收缩的协调纤维状结构域模型，其中收缩的初始阶段和持续阶段由不同的细胞和分子事件介导。反应的初始阶段由[Ca2+]c升高介导，由此导致肌球蛋白轻链激酶的钙调蛋白依赖性激活以及钙调蛋白从肌动蛋白-钙调蛋白-原肌球蛋白-肌球蛋白纤维状结构域解离。这些事件导致肌动蛋白与肌球蛋白磷酸化轻链之间的相互作用，正如之前的模型一样。然而，这个初始阶段之后是一个持续阶段，其中[Ca2+]sm升高刺激与质膜相关的、对Ca2+敏感的蛋白激酶C形式，导致细丝蛋白-肌动蛋白-结蛋白纤维状结构域的结构和调节成分磷酸化。这些事件构成了收缩的强直阶段的基础。
