STRUCTURE OF MYOSIN-CONTAINING FILAMENT ASSEMBLY (A-SEGMENT) SEPARATED FROM FROG SKELETAL MUSCLE
STRUCTURE OF MYOSIN-CONTAINING FILAMENT ASSEMBLY (A-SEGMENT) SEPARATED FROM FROG SKELETAL MUSCLE
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DOI：
10.1016/0022-2836(71)90045-3
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发表时间：
1971-01-01
影响因子：
5.6
通讯作者：
BENNETT, PM
中科院分区：
文献类型：
--
作者：
HANSON, J;OBRIEN, EJ;BENNETT, PM
A段和I段分别是含有肌球蛋白和含肌动蛋白的细丝的自然集合，通过在松弛介质中机械破坏青蛙骨骼肌原纤维而释放出来。在电子显微镜下，阴性染色的A段(长度~1.6μm)比分离的细丝或切片纤维显示出更详细的周期性结构。这种结构是两极的。中间的M波段(宽度~495？)两侧是一个染色很深的“裸露”区(宽度~395？)，紧随其后的是一系列10个等宽的频带(420？±15？)，显示一个偏振的子结构；段的末端具有较不规则的结构。频段1、2和3与频段4到10不同，它们看起来都很相似。在某些方面，来自这十条带区域的光学衍射图类似于来自浅色肌球蛋白准晶体的显微照片的图样。较重的肌球蛋白突起的排列不明显；可能它们已被染色破坏。没有发现442？周期的证据。结论是，观察到的带型主要代表了轻质肌球蛋白细丝骨架的双极结构。
A- and I-segments, which are the naturally occurring assemblies of the myosin-containing and actin-containing filaments, respectively, have been released by mechanical disruption of frog skeletal myofibrils in a relaxing medium. In the electron microscope, negatively stained A-segments (length ~1.6 μm) show periodic structure in much more detail than is observed in isolated filaments or sectioned fibrils. The structure is bipolar. The central M-band (width ~495 Å) is flanked on either side by a heavily stained “bare” zone (width ~395 Å), following which is a series of ten bands of equal width (420 Å ± 15 Å) showing a polarised substructure; the end of the segment has a less regular structure. Bands 1, 2 and 3 differ from bands 4 to 10, which all look alike. Optical diffraction patterns from the region of the ten bands resemble, in certain respects, the patterns from micrographs of light meromyosin paracrystals. The arrangement of the heavy meromyosin projections is not apparent; probably they have been damaged by the stain. No evidence was found of a 442 Å periodicity. It is concluded that the band pattern observed represents mainly the bipolar structure of the light meromyosin filament backbone.