Contractile Mechanisms in Muscle
Contractile Mechanisms in Muscle
复制标题
肌肉的收缩机制
DOI：
10.1007/978-1-4684-4703-3
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发表时间：
1984
影响因子：
--
通讯作者：
杉 晴夫
中科院分区：
文献类型：
--
作者：
G. Pollack;杉 晴夫
1.从低剂量（10电子/A2）和高剂量（>500电子/A2）的电子显微镜图像中重建了肌动蛋白-原肌球蛋白81的“僵硬”复合物的三维图像。2.肌球蛋白81显示出多结构域亚分子结构，如早先在肌动蛋白-81（Wakabayshi & Toyoshima，1981）和肌动蛋白重酶解肌球蛋白（Katayama & Wakabayashi，1981）中观察到的。肌动蛋白原肌球蛋白81的形态单位至少由三个结构域（结构域A、B和D）和三个区域（C、E和H）组成。3.肌球蛋白Sl分子具有复杂的形状，其不能由具有一个主轴的简单杆来表示。S1的形状应该由至少两个杆近似。4.域D被确定为S1的主要部分。该结构域的长轴与肌动蛋白螺旋轴的夹角约为72°，几乎为直角。5.肌动蛋白螺旋轴与E区长轴之间的夹角比D区小，且不与肌动蛋白接触，远小于D区。6.高剂量和低剂量显微照片的重建图像的分辨率得到提高，使得径向分辨率变为约15 A，轴向分辨率变为约25 A。由于在径向和轴向方向上的分辨率的提高，所有主要域A、B和D分裂成两个域，即分别分裂成A1和A2、H1和B2以及D1和D2。7.虽然我们还没有明确的肌动蛋白的归属，但可以证实，一个81分子在两个位点上与肌动蛋白发生形态学相互作用（Wakabayashi & Toyoshima，1981）。
1. A three-dimensional image of the "rigor" complex of actin-tropomyosin81 was reconstituted from both low dose (10 electrons/A 2) and high dose (>500 electrons/A 2) electron microscopic images of specimens embedded in unbroken and unbacked stain sheets of uranyl acetate over the holes of perforated carbon films. 2. Myosin 81 shows multi-domain submolecular structure as has been earlier observed in actin-81 (Wakabayshi & Toyoshima, 1981) and actinheavy meromyosin (Katayama & Wakabayashi, 1981). The morphological unit of the actin-tropomyosin-81 was found to be composed of at least three domains (domains A, B and D) and three regions (C, E and H). 3. A myosin Sl molecule has a complex shape, which cannot be represented by a simple rod with one major axis. The shape of Sl should be approximated by at least two rods. 4. The domain D is identified as the main part of S1. The angle between the major axis of this domain and the axis of actin helix was about 72°, which 1s almost right angle. 5. The angle between the axis of actin helix and major axis of the region E, which is less bulky than the domain D and makes no contact with actin, is much smaller than the value for the domain D. 6. The resolution of reconstituted images from both high and low dose micrographs was improved so that the radial resolution became about 15 A and the axial one became about 25 A. Due to the improvement of resolution in both the radial and axial direction, ali major domains A, B and D split into two domains, i.e. into Ai and A2, Hi and B2, and Dl and D2 respectively. 7. Though unambiguous assignment of actin is not yet achieved by us, it can be confirmed that a 81 molecule interacts morphologically with actin at two sites (Wakabayashi & Toyoshima, 1981).