The activity of cardiac and skeletal muscles depends upon the ATP-coupled actin–myosin interactions to execute the power stroke and muscle contraction. The goal of this review article is to provide insight into the function of myosin II, the molecular motor of the heart and skeletal muscles, with a special focus on the role of myosin II light chain (MLC) components. Specifically, we focus on the involvement of myosin regulatory (RLC) and essential (ELC) light chains in striated muscle development, isoform appearance and their function in normal and diseased muscle. We review the consequences of isoform switching and knockout of specific MLC isoforms on cardiac and skeletal muscle function in various animal models. Finally, we discuss how dysregulation of specific RLC/ELC isoforms can lead to cardiac and skeletal muscle diseases and summarize the effects of most studied mutations leading to cardiac or skeletal myopathies.

心肌和骨骼肌的活动取决于 ATP 偶联的肌动蛋白 - 肌球蛋白相互作用来执行动力冲程和肌肉收缩。这篇综述文章的目的是深入了解肌球蛋白 II（心脏和骨骼肌的分子运动）的功能，特别关注肌球蛋白 II 轻链 (MLC) 成分的作用。具体来说，我们重点关注肌球蛋白调节（RLC）和必需（ELC）轻链在横纹肌发育中的参与、异构体的出现及其在正常和患病肌肉中的功能。我们回顾了异构体转换和特定 MLC 异构体​​敲除对各种动物模型中心脏和骨骼肌功能的影响。最后，我们讨论了特定 RLC/ELC 亚型的失调如何导致心脏和骨骼肌疾病，并总结了大多数研究的导致心脏或骨骼肌病的突变的影响。