Fluorescence resonance energy transfer in acto-myosin complexes.
Fluorescence resonance energy transfer in acto-myosin complexes.
复制标题
肌动球蛋白复合物中的荧光共振能量转移。
DOI：
10.1007/978-3-540-46558-4_3
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Berger,ChristopherL
中科院分区：
文献类型：
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作者：
Yengo,ChristopherM;Berger,ChristopherL
肌球蛋白是肌动蛋白结合蛋白中最著名和研究最多的一种，是一种分子马达蛋白，在肌肉收缩、胞质分裂和细胞的其他运动功能中将ATP水解的化学能转化为机械功。在分子水平上，肌肉收缩被认为是指状交叉的粗（主要由肌球蛋白组成）和细（由肌动蛋白和大量钙调节蛋白组成）肌丝相互滑动的结果。这被认为是一个循环过程，其中ATP的水解介导肌动蛋白和肌球蛋白之间的相互作用（Eisenberg和Hill，1985）。肌球蛋白的ATP酶循环至少由四种不同的结构状态组成。肌球蛋白最初在缺乏核苷酸的情况下与肌动蛋白结合，或者在收缩周期结束时与肌动蛋白结合在僵硬复合物（AM）中。在加入ATP（M. ATP）时，肌球蛋白对肌动蛋白的亲和力显著降低，导致肌动蛋白-肌球蛋白复合物解离。然后ATP被水解形成第二个弱结合态（M. ADP Pi），就像M。ATP状态下，对肌动蛋白的亲和力相对较低。在释放ATP水解产物（ADP和Pi）的过程中，由于对肌动蛋白的亲和力增加，发生了从”弱”到”强”结合的转变，并且肌球蛋白通过改变横桥相对于肌动蛋白丝之间的角度（即，动力冲程）产生力。最后，肌球蛋白恢复到僵硬状态（AM），这是肌动蛋白和肌球蛋白之间最高的亲和力状态。从结构上理解ATP与肌球蛋白的结合如何极大地降低其与肌动蛋白的亲和力，以及ATP的水解如何引发跨桥是至关重要的（肌球蛋白头）在强结合状态和随后的动力冲程中重新结合肌动蛋白，如果化学机械耦合和肌肉收缩的分子机制被完全理解，骨骼肌肌球蛋白II的整体结构是一个由两条重链（“200 kDa”）和两组轻链形成的六聚体，每组轻链包括一条调节性和必需性轻链（“20 kDa”）。肌球蛋白可以通过蛋白水解分离成卷曲螺旋片段的轻肌球蛋白
Myosin, the best known and most studied actin-binding protein, is a molecular motor protein that converts the chemical energy of ATP hydrolysis into mechanical work during muscle contraction, cytokinesis, and other motile functions of cells. At the molecular level muscle contraction is believed to result from the relative sliding of interdigitated thick (composed primarily of myosin) and thin (composed of actin and a host of calcium-regulatory proteins) filaments past one another. This is thought to be a cyclic process in which the hydrolysis of ATP mediates the interaction between actin and myosin (Eisenberg and Hill, 1985). The ATPase cycle of myosin consists of at least four distinct structural states. Myosin is initially bound to actin in the absence of nucleotide, or in a rigor complex (AM), at the end of the contractile cycle. Upon the addition of ATP (M. ATP), the affinity of myosin for actin is significantly reduced, causing dissociation of the acto-myosin complex. ATP is then hydrolyzed to form a second weakly bound state (M. ADP. Pi) which, like the M. ATP state, has a relatively low affinity for actin. During the process of releasing the products of ATP hydrolysis (ADP and Pi), a transition from" weak" to" strong" binding occurs, due to an increase in affinity for actin, and myosin generates force by changing the angle between the cross-bridge relative to the actin filament (ie, the power stroke). Finally, myosin returns to the rigor state (AM), which is the highest-affinity state between actin and myosin. It is critically important to understand structurally how the binding of ATP to myosin greatly reduces its affinity for actin, and how the hydrolysis of ATP primes the cross-bridge (myosin head) for rebinding to actin in the strongly bound state and the subsequent power stroke, if chemomechanical coupling and the molecular mechanism of muscle contraction are ever to be completely understood.The overall structure of skeletal muscle myosin II is a hexamer that is formed by two heavy chains ("" 200kDa) and two sets of light chains, each including a regulatory and essential light chain ("" 20 kDa each). Myosin can be separated by proteolysis into a coiled-coil fragment of light meromyosin