Tokuyasu K T, Dutton A H, Singer S J
J Cell Biol. 1983 Jun;96(6):1727-35. doi: 10.1083/jcb.96.6.1727.
We studied the localization of desmin (skeletin), the major subunit of muscle-type intermediate filaments, by high resolution immunoelectron microscopy in adult chicken skeletal muscle. Immunoferritin labeling of ultrathin frozen sections of intact fixed sartorius muscle showed the presence of desmin between adjacent Z-bands and as strands peripheral to Z-bands, forming apparent connections between the Z-bands with adjacent sarcolemma, mitochondria, and nuclei. We observed no desmin labeling, however, in the vicinity of the T-tubules. In addition, intermediate filaments were morphologically discernible at the level of the Z-bands in plastic sections of glycerol-extracted muscle that had been infused with unlabeled antidesmin antibodies. Our results indicate that the desmin present in adult skeletal muscle, that had previously been detected by immunofluorescence light microscopy, is largely if not entirely in the form of intermediate filaments. The results provide evidence that these filaments serve to interconnect myofibrils at the level of their Z-bands, and to connect Z-bands with other specific structures and organelles in the myotube, but not with the T-tubule system.
我们通过高分辨率免疫电子显微镜研究了成年鸡骨骼肌中肌间线蛋白（骨架蛋白）的定位，肌间线蛋白是肌肉型中间丝的主要亚基。完整固定的缝匠肌超薄冰冻切片的免疫铁蛋白标记显示，肌间线蛋白存在于相邻Z线之间，并呈Z线周围的条索状，在Z线与相邻肌膜、线粒体和细胞核之间形成明显的连接。然而，我们在T小管附近未观察到肌间线蛋白标记。此外，在注入未标记抗肌间线蛋白抗体的甘油抽提肌肉的塑料切片中，在Z线水平可在形态上辨别出中间丝。我们的结果表明，先前通过免疫荧光光学显微镜检测到的成年骨骼肌中的肌间线蛋白，即使不是完全，也大部分以中间丝的形式存在。结果提供了证据，表明这些细丝有助于在肌原纤维的Z线水平将其相互连接，并将Z线与肌管中的其他特定结构和细胞器相连，但不与T小管系统相连。
