Muscle thin-filament structure and regulation. Actin sub-domain movements and the tropomyosin shift modelled from low-angle X-ray diffraction
Muscle thin-filament structure and regulation. Actin sub-domain movements and the tropomyosin shift modelled from low-angle X-ray diffraction
复制标题
肌肉细丝结构和调节。
DOI：
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
N. Yagi
中科院分区：
文献类型：
--
作者：
J. Squire;Hind A. Al;N. Yagi
脊椎动物肌肉在非重叠肌节长度的松弛状态和激活状态的低角X射线衍射数据被用来模拟肌动蛋白单体和原肌球蛋白链的四个结构亚域的相对位置，并研究由于钙离子激活而发生的变化。该模型基于：(I)已发表的肌动蛋白-DNA酶I的晶体结构[W.Krupch，H.G.Mannherz，D.Suck，E.F.Pai和K.C.Holmes，Nature(伦敦)，1990,347，37]，(Ii)F-肌动蛋白细丝的模拟[K.C.Holmes，D.Popp，W.Gebhard和W.Krupch，Nature(伦敦)，1990,347，44]，(Iii)公开测量F-肌动蛋白、F-肌动蛋白加原肌球蛋白和单独的原肌球蛋白链的回转半径，(Iv)我们自己和已发表的来自肌动蛋白细丝的低角X射线衍射图中的层线位置和强度，以及(V)对肌动蛋白亚域运动和细丝结构的敏感的空间位阻限制。结论是，即使肌动蛋白分子有四个亚域结构，当静止的肌球蛋白被钙激活时，如果原肌球蛋白链没有实质性的方位摆动(约20°)，也不能解释观察到的低角X射线衍射图。这种钙离子激活的摆动方向远离肌动蛋白上肌球蛋白结合位点的位置；这一结果与肌动蛋白细丝调节的原始‘空间阻断模型’一致，在该模型中，原肌球蛋白在肌动蛋白上的位置对于肌球蛋白在肌动蛋白上的交叉桥循环的调节至关重要。
Low-angle X-ray diffraction data from vertebrate muscles in the relaxed state and in the activated state at non-overlap sarcomere lengths have been used to model the relative positions of the four structural sub-domains of the actin monomer and of the tropomyosin strands and to investigate the changes that occur as a result of Ca2+ activation. The model is based on: (i) the published crystal structure of actin–DNase I [W. Kabsch, H. G. Mannherz, D. Suck, E. F. Pai and K. C. Holmes, Nature(London), 1990, 347, 37], (ii) the modelling of the F-actin filament [K. C. Holmes, D. Popp, W. Gebhard and W. Kabsch, Nature(London), 1990, 347, 44], (iii) published measurements of the radii of gyration of F-actin, of F-actin plus tropomyosin and of the tropomyosin strands alone, (iv) our own and published layer-line positions and intensities in the low-angle X-ray diffraction patterns from actin filaments, and (v) sensible steric constraints on actin sub-domain movements and thin filament structure. It is concluded that, even with a four sub-domain structure for actin molecules, the observed low-angle X-ray diffraction patterns cannot be explained without a substantial azimuthal swing (about 20°) of the tropomyosin strands when resting filaments are Ca2+-activated. The direction of this swing on Ca2+-activation is away from a position close to the proposed myosin binding site on actin; a result consistent with the original ‘steric blocking model’ of actin filament regulation in which tropomyosin position on actin is crucial for regulation of the myosin crossbridge cycle on actin.
DOI：
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发表时间：
1981
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Chalovich,JM;Chock,PB;Eisenberg,E
通讯作者：
Eisenberg,E
通过中子散射测定肌动原肌球蛋白中原肌球蛋白分子的交叉螺旋分离。
影响因子：
3.4
作者：
Bivin,DB;Stone,DB;Schneider,DK;Mendelson,RA
通讯作者：
Mendelson,RA