Morphology of isolated triads.
Morphology of isolated triads.
复制标题
DOI：
10.1083/jcb.96.4.1017
复制
发表时间：
1983-04
期刊：
影响因子：
--
通讯作者：
Fleischer S
中科院分区：
文献类型：
--
作者：
Mitchell RD;Saito A;Palade P;Fleischer S
三联体是横小管与肌浆网终池的连接。从骨骼肌中分离高度富集的三联体的方法已在先前的论文中描述。在本研究中，孤立的三联体的结构特征已被检查的薄切片，负染色，冷冻断裂电子显微镜。在孤立的三联体中，原位观察到的结构的关键特征被保留下来，包括嗜锇性“足”，横小管和终末池之间的连接结构。通过负染色获得了对三联体结构的新认识，这也使得在终末池的交界面处可以看到足，而较小的表面颗粒（钙泵蛋白的特征）在那里看不到。因此，连接面不同于肌浆网膜的其余部分。通过薄切片或负染色观察到的连接足具有相似的周期性，并从膜表面延伸约100 A。冷冻断裂孤立的黑社会揭示了块状结构与膜的终端池在交界面，终端池和t-小管之间的连接，和intragap颗粒。可以观察到间隙内颗粒与t小管密切相关。孤立的三合会的结构容易受到渗透和盐扰动，并给出了关于横小管和终端cistererestrium的差异影响的例子。在三元组的实验以及它们的制备和处理中，必须考虑对形态产生不利影响的条件。
The triad is the junctional association of transverse tubule with sarcoplasmic reticulum terminal cisternae. A procedure for the isolation of highly enriched triads from skeletal muscle has been described in the previous paper. In the present study, the structural features of isolated triads have been examined by thin-section, negative-staining, and freeze-fracture electron microscopy. In isolated triads, key features of the structure observed in situ have been retained, including the osmiophilic "feet," junctional structures between the transverse tubule and terminal cisternae. New insight into triad structure is obtained by negative staining, which also enables visualization of feet at the junctional face of the terminal cisternae, whereas smaller surface particles, characteristic of calcium pump protein, are not visualized there. Therefore, the junctional face is different from the remainder of the sarcoplasmic reticulum membrane. Junctional feet as viewed by thin section or negative staining have similar periodicity and extend approximately 100 A from the surface of the membrane. Freeze-fracture of isolated triads reveals blocklike structures associated with the membrane of the terminal cisternae at the junctional face, interjunctional connections between the terminal cisternae and t-tubule, and intragap particles. The intragap particles can be observed to be closely associated with the t-tubule. The structure of isolated triads is susceptible to osmotic and salt perturbation, and examples are given regarding differential effects on transverse tubules and terminal cisternae. Conditions that adversely affect morphology must be considered in experimentation with triads as well as in their preparation and handling.