A network of transverse and longitudinal intermediate filaments is associated with sarcomeres of adult vertebrate skeletal muscle.
A network of transverse and longitudinal intermediate filaments is associated with sarcomeres of adult vertebrate skeletal muscle.
复制标题
横向和纵向中间丝网络与成年脊椎动物骨骼肌的肌节相关。
DOI：
10.1083/jcb.96.2.562
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Ramirez-Mitchell,R
中科院分区：
文献类型：
--
作者：
Wang,K;Ramirez-Mitchell,R
当用 KI 提取由 Triton-EGTA 处理的兔骨骼肌制备的小肌原纤维束以去除大部分细丝和粗丝时，显示了广泛的横向和纵向丝状桥网络。对这些耐盐细胞骨架残基的透射和扫描电子显微镜研究表明：(a) 小束短横向丝通过形成 Z 到 Z 和 M 到 M 桥连接相邻的肌原纤维；(b) 平行、连续的纵向丝连接连续 Z 盘的外围并包住肌节。这些横向和纵向细丝具有中间细丝的特征形态；（c）两个紧密交织和缠结的细丝环，通过短丝横向连接，包围每个Z盘。这个双环还围绕着一个网状网状结构，该网状结构穿透肌节空间。从这些环的周边，出现横向和纵向的中间丝； (d) KI 提取过程中，大量材料在 Z 盘附近移位和积累。残留物对尿素和 SDS 的溶解具有相当的抵抗力，并且只有使用氯化胍才能实现完全溶解。 SDS PAGE表明残基主要由肌联蛋白、星云蛋白以及不同量的残余肌球蛋白和肌动蛋白组成。结蛋白仅占总残留蛋白的百分之几；然而，它可能是中间长丝网络的主要组成部分。我们建议，中间丝应被视为一个完整的肌节成分，可能在肌肉结构和力学中发挥重要的细胞骨架作用。骨骼肌和心肌的特征性交叉纹状外观是由于相邻肌原纤维的肌节条纹横向排列而产生的。这种排列的维持归因于 Z 盘之间以及穿过纤维轴的 M 线之间存在丝状桥（有关评论，请参阅参考文献 16、17）。大多数研究都集中在连接相邻肌原纤维的基本桥上，即横向的原纤维间类型。然而，很少有人注意到可能存在纵向原纤维内桥，这些桥可能连接同一肌原纤维的相邻肌节结构。跨越 IZI 刷之间或同一肌原纤维 Z 结构之间间隙的残余纵向细丝已被
An extensive network of transverse and longitudinal filamentous bridges was revealed when small myofibril bundles, prepared from Triton-EGTA-treated rabbit skeletal muscles, were extracted with KI to remove the majority of thin and thick filaments. Transmission and scanning electron microscopic studies of these salt-resistant cytoskeletal residues indicated:(a) small bundles of short transverse filaments connect adjacent myofibrils by forming Z to Z and M to M bridges;(b) parallel, continuous longitudinal filaments connect the peripheries of successive Z-disks and ensheath the sarcomere. These transverse and longitudinal filaments have the characteristic morphology of intermediate filaments;(c) two rings of tightly interwoven and tangled filaments, connected laterally by short filaments, encircle each Z disk. This doublering also encircles a weblike meshwork which penetrates the sarcomeric space. From the peripheries of these rings, transverse and longitudinal intermediate filaments emerge; and (d) a massive amount of, material translocated and accumulated near Z disks during KI extraction. The residues were fairly resistant to solubilization by urea and SDS, and complete dissolution was achieved only with guanidinium chloride. SDS PAGE indicated that the residues consisted mainly of titin, nebulin, and variable amounts of residual myosin and actin. Desmin represented only a few percent of total residual proteins; however, it may be a major component of the intermediate filament network. We suggest that the intermediate filament should be considered an integral sarcomeric component that may play important cytoskeletal roles in muscle structure and mechanics.The characteristic cross-striated appearance of skeletal and cardiac muscles arises as a result of the transverse alignment of sarcomeric striations of neighboring myofibrils. The maintenance of this alignment has been attributed to the existence of filamentous bridges between Z disks and between M-lines across the fiber axis (for reviews, see references 16, 17). Most studies have focused on the fdamentous bridges that connect neighboring myofibrils--ie, the transverse, interfibrillar type. However, little attention has been paid to the possible existence of longitudinal, intrafibrillar bridges that may connect adjacent sarcomeric structures of the same myofibril. Residual longitudinal filaments spanning the gaps between IZI brushes or between Z structures of the same myofibril have been