X-RAY EVIDENCE FOR A CONFORMATIONAL CHANGE IN ACTIN-CONTAINING FILAMENTS OF VERTEBRATE STRIATED-MUSCLE
X-RAY EVIDENCE FOR A CONFORMATIONAL CHANGE IN ACTIN-CONTAINING FILAMENTS OF VERTEBRATE STRIATED-MUSCLE
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DOI：
10.1101/sqb.1973.037.01.044
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发表时间：
1973-01-01
期刊：
影响因子：
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通讯作者：
HASELGROVE, JC
中科院分区：
文献类型：
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作者：
HASELGROVE, JC
脊椎动物横纹肌从静止到活动的控制由细肌动蛋白丝上的调节蛋白原肌球蛋白和肌钙蛋白的组合调节（参见Ebashi和Endo，1968; Ebashi等人，1969年）。在缺乏钙的情况下，调节蛋白抑制肌动蛋白相互作用。肌肉的激活是由钙与肌钙蛋白结合引起的，然后肌钙蛋白消除抑制。由于对于每七个肌动蛋白分子只有一个肌钙蛋白分子（Weber和Bremel，1971），并且肌钙蛋白不与肌动蛋白相互作用，那么激活的控制可能是由沿着肌动蛋白丝中的沟槽沿着行进的原肌球蛋白分子介导的（Hanson和Lowy，1963;摩尔等人，1971年）。因此，研究肌动蛋白-肌球蛋白相互作用时细丝中发生的任何结构变化是很重要的，因为这些变化可以给我们关于控制机制的信息。X射线衍射用于研究肌肉具有很大的优势，可以在分子水平上研究结构而不破坏标本。低角度X光图像脊椎动物横纹肌的层线（对应于约20埃以上的间距）由层线和肌球蛋白丝和肌动蛋白丝产生的层线反射组成（Huxley和Brown，1967年），因此，通过观察低角衍射图案的变化，以跟踪当肌肉收缩或进入僵直状态时细丝结构中发生的变化。X射线衍射研究肌肉的最大缺点是它们不能直接给出肌肉结构的信息;必须首先从其他研究中假设结构，如果它给出的衍射图案与观察到的图案相似，则结构可以被接受。
The control of vertebrate striated muscle from rest to activity is regulated by the combination of the regulatory proteins tropomyosin and troponin on the thin actin filament (see reviews by Ebashi and Endo, 1968; Ebashi et al., 1969). In the absence of calcium the regulatory proteins inhibit the actinmyosin interaction. Activation of muscle is caused by calcium binding to troponin which then removes the inhibition. Since there is only one troponin molecule for evmy seven actin molecules (Weber and Bremel, 1971) and troponin does not interact with actin, then the control of activation is presumably mediated by the tropomyosin molecules which run along the grooves in the actin filaments (Hanson and Lowy, 1963; Moore et al., 1971). It is, therefore, of importance to investigate any structural changes that occur in the thin filaments when actin-myosin interaction is allowed to take place, for such changes may give us information about the control mechanism. X-ray diffraction for the study of muscle has the great advantage that the structure can be studied at the molecular level without destruction of the specimen. The low-angle X-ray pattern (corresponding to spacings above about 20A) from vertebrate striated muscle consists of layer lines and meridional reflections that arise both from the myosin filaments and from the actin filaments (Huxley and Brown, 1967), so it is possible, by observing changes in the lowangle diffraction pattern, to follow changes occurring in the thin filament structure when the muscle contracts or passes into rigor. The great disadvantage of X-ray diffraction studies on muscle is that they do not give information directly about the muscle structure; the structure must first be assumed from other studies and the structure can be accepted if it gives a diffraction pattern like the observed pattern.