TROPOMYOSIN CRYSTAL-STRUCTURE AND MUSCLE REGULATION
TROPOMYOSIN CRYSTAL-STRUCTURE AND MUSCLE REGULATION
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DOI：
10.1016/0022-2836(86)90468-7
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发表时间：
1986-11-05
影响因子：
5.6
通讯作者：
COHEN, C
中科院分区：
文献类型：
--
作者：
PHILLIPS, GN;FILLERS, JP;COHEN, C
原肌球蛋白丝的晶体结构已解为15埃。通过对衍射数据和半胱氨酸残基的重原子标记的模型的细化来解析。这些结果证实并扩展了早期的发现。改进的地图揭示了螺旋线圈的间距，半胱氨酸残基的位置，以及在细丝中重叠的分子末端的位置和特征。现在可以在氨基酸序列的区域和分子的关键特征之间建立相关性，例如晶格中的接触位点和沿着沿着卷曲螺旋偏离规则性。晶体显示出显着的动态特性和相对灵活性的不同部分的分子，以及其各向异性的字符已被确定。原肌球蛋白在晶体中的结构和运动提供了肌肉原肌球蛋白结构及其可能的调节作用的信息。基于低分辨率X-射线结果，连同α-β的立体化学，已经构建了分子的原子模型。螺旋盘绕线圈。与先前的观点相反，该分子似乎仅显示一组七个α-允许柔性原肌球蛋白丝与肌动蛋白螺旋弱连接的位点。相应地，我们描绘了在ATP酶活性的“关闭”状态下，位置未被占用：在“开”状态下，它们仅被部分占用;而在“增强”状态下，它们更完全地饱和。因此，收缩的控制被视为一种统计机制，需要至少三个不同的平均构象的肌动蛋白螺旋上的原肌球蛋白分子。
The crystal structure of tropomyosin filaments has been solved to 15 .ANG. resolution by refinement of models against the diffraction data and heavy atom labeling of cysteine residues. These results confirm and extend earlier findings. The improved maps reveal the pitch of the coiled coil, the location of the cysteine residues, and the location and features of the overlapping molecular ends in the filaments. A correlation can now be made between regions of the amino acid sequence and key features of the molecule, such as contact sites in the lattice and departures from reqularity along the coiled coil. The crystal shows remarkable dynamic features and the relative flexibility of different parts of the molecule as well as its anisotropic character have been determined. The structure and motions of tropomyosin in the crystal provide information on the structure of tropomyosin in muscle and its possible role in regulation. An atomic model of the molecule has been constructed, based on the low resolution X-ray results, together with the stereochemistry of .alpha.-helical coiled coils. In contrast to previous views, the molecule appears to display but one set of seven .alpha.-sites that permit weak linkages of the flexible tropomyosin filament to the actin helix. Correspondingly, we picture that in the "off" state of ATPase activity, the .alpha.-sites are not occupied: in the "on" state, they are only partly occupied: and in the "potentiated" state, they are more completely saturated. Control of contraction is therefore seen as a statistical mechanism requiring at least three distinct average conformations for the tropomyosin molecule on the actin helix.