EXISTENCE OF AN INSOLUBLE Z-DISC SCAFFOLD IN CHICKEN SKELETAL-MUSCLE
EXISTENCE OF AN INSOLUBLE Z-DISC SCAFFOLD IN CHICKEN SKELETAL-MUSCLE
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DOI：
10.1016/0092-8674(78)90051-x
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发表时间：
1978-01-01
期刊：
影响因子：
64.5
通讯作者：
LAZARIDES, E
中科院分区：
文献类型：
--
作者：
GRANGER, BL;LAZARIDES, E
用0.6 M K I提取甘油鸡骨骼肌，在每个肌纤维内留下不溶性组分的框架。该框架主要由对齐Z盘的平面组成，Z盘在提取期间通过每个盘两侧的材料积累而增厚。膜囊泡，可能是T系统的残余物，仍然围绕着Z盘。当框架在混合器中剪切时，其优先在Z平面之间裂解，导致形成蜂窝状阵列中的互连的、紧密堆积的Z盘的大片。裂解发生在以前由A带占据的区域，该区域由于肌球蛋白的去除而减弱。这些平面Z圆盘阵列的存在和稳定性证明了相邻肌原纤维之间的连接的存在和强度。SDS-聚丙烯酰胺凝胶电泳显示，该构架主要由肌动蛋白和结蛋白组成，具有较少量的几种蛋白质，包括α-肌动蛋白、肌球蛋白和原肌球蛋白。Z盘片和KI提取的肌原纤维分别提供Z盘的不同的正面视图和侧视图。在间接免疫荧光中，这2个视图显示结蛋白存在于每个Z盘的外周，在Z平面内形成蛋白质套环的网络。α-辅肌动蛋白位于每个圆盘内，给出与结蛋白互补的荧光图案。肌动蛋白存在于整个增厚的Z平面，而肌球蛋白和原肌球蛋白只存在于不溶性残留物中，这些残留物合并在每个圆盘的两面。结蛋白，也许与肌动蛋白，是负责相互连接的Z光盘相邻的肌原纤维，并因此可能作为一个机械和结构的肌纤维的集成商。它的疏水性和与T系统一致的分布表明，它也可能是resible介导的粘附-膜相互作用和锚定的三联体的Z盘。它的衣领状分布表明，它可能有助于保持结构完整性的Z盘和插入其中的肌动蛋白丝。
Extraction of glycerinated chicken skeletal muscle with 0.6 M K I leaves a framework of insoluble components within each muscle fiber. This framework is composed primarily of planes of in-register Z discs that were thickened by the accumulation of material on both sides of each disc during extraction. Membrane vesicles, presumably remnants of the T system, remain surrounding the Z discs. When the framework is sheared in a blender, it is preferentially cleaved between Z planes, resulting in the formation of large sheets of interconnected, closely packed Z discs in a honeycomb-like array. Cleavage occurs in regions formerly occupied by the A bands, which were weakened by the removal of myosin. The existence and stability of these planar Z disc arrays demonstrate the presence and strength of connections between adjacent myofibrils. SDS-polyacrylamide gel electrophoresis reveals that this framework consists primarily of actin and desmin, with lesser amounts of a few proteins including .alpha.-actinin, myosin and tropomyosin. Z disc sheets and Kl-extracted myofibrils provide a distinct face-on view and side view, respectively, of the Z disc. In indirect immunofluorescence, these 2 views revealed that desmin is present at the periphery of each Z disc, forming a network of proteinaceous collars within the Z plane. .alpha.-Actinin is localized within each disc, giving a face-on fluorescence pattern that is complementary to that of desmin. Actin is present throughout the thickened Z plane, while myosin and tropomyosin exist only in the insoluble residue that coalesces on both faces of each disc. Desmin, perhaps in conjunction with actin, is responsible for interlinking Z discs of adjacent myofibrils, and may thus serve as a mechanical and structural integrator of muscle fibers. Its hydrophobic nature and coincident distribution with the T system suggest that it may also be resonsible for mediating filament-membrane interactions and anchoring the triad to the Z disc. Its collar-like distribution suggests that it may aid in maintaining the structural integrity of the Z disc and the actin filaments inserted into it.