Binding of myosin subfragment 1 to glycerinated insect flight muscle in the rigor state.
Binding of myosin subfragment 1 to glycerinated insect flight muscle in the rigor state.
复制标题
肌球蛋白亚片段 1 在严格状态下与甘油化的昆虫飞行肌结合。
DOI：
10.1016/s0006-3495(85)83889-3
复制
发表时间：
1985
影响因子：
3.4
通讯作者：
Reedy,MK
中科院分区：
文献类型：
--
作者：
Goody,RS;Reedy,MC;Hofmann,W;Holmes,KC;Reedy,MK
用低角X射线衍射、定量十二烷基硫酸钠凝胶电泳、定量干涉显微镜和电子显微镜研究了兔肌肌球蛋白亚片段1（S1）与甘油化昆虫飞行肌纤维的结合。在严谨的X-射线衍射图案诱导的变化是一致的想法，即空置的肌球蛋白结合位点的细丝填充外源性S1。电子显微镜表明，S1渗透和标记纤维和原纤维完全。电子显微照片还表明，在所使用的条件下，跨桥不被外源性S1取代，这是由S1标记的纤维的不变的机械刚度支持的。结合S1的量，通过凝胶电泳和干涉显微镜，连同在X-射线衍射图中的强度变化的幅度，是一致的厚丝结构，包含4个分子的内源性肌球蛋白每14.5 nm的长度，但不同意与早期估计的6个肌球蛋白每冠。缺乏关于交叉桥以外的因素可能抑制S1结合的信息，例如，肌钙蛋白，使僵硬状态下连接的横桥数量的计算不确定。然而，似乎至少有75%的内源性肌球蛋白头是附着的。在与S1孵育后，细丝上的结合位点的占有率很高，可能大于85%，因此，从粘附于细丝对称性的结构的那些部分的X射线散射可以被视为从S1装饰的细丝的衍射。此外，我们在薄的喇叭形X横截面中显示，exo-S1头与肌动蛋白结合，其几何形状在Taylor，K.A.，和洛杉矶艾莫斯
The binding of rabbit muscle myosin subfragment 1 (S1) to glycerinated insect flight muscle fibers has been studied by low-angle x-ray diffraction, quantitative sodium dodecyl sulfate gel electrophoresis, quantitative interference microscopy, and electron microscopy. Changes induced in the rigor x-ray diffraction pattern are consistent with the idea that vacant myosin-binding sites on thin filaments are filled by exogenous S1. Electron microscopy indicates that S1 permeates and labels fibers and fibrils completely. Electron micrographs also show that cross-bridges are not displaced by exogenous S1 under the conditions used, and this is supported by the unchanged mechanical stiffness of the S1-labeled fibers. The amount of bound S1, as measured by gel electrophoresis and interference microscopy, together with the magnitude of the intensity changes in the x-ray diffraction pattern, is consistent with a thick filament structure that contains four molecules of endogenous myosin per 14.5 nm of its length, but does not agree well with earlier estimates of six myosins per crown. Lack of information on possible inhibition of S1-binding by factors other than the presence of cross-bridges, e.g., troponin, render uncertain calculations of the number of attached cross-bridges in the rigor state. However, it appears that at least 75% of the endogenous myosin heads are attached. Occupancy of binding sites on thin filaments after incubation with S1 is high, probably greater than 85%, so that x-ray scattering from those parts of the structure that adhere to the symmetry of the thin filaments can be treated as diffraction from S1-decorated thin filaments. In addition, we show in thin flared X cross sections that exo-S1 heads bind to actin with the geometry described in decorated actin by Taylor, K.A., and L.A. Amos.