Lowrey A A, Kaufman S J
Department of Microbiology, University of Illinois, Urbana 61801.
Exp Cell Res. 1989 Jul;183(1):1-23. doi: 10.1016/0014-4827(89)90414-x.
Plasma membrane-cytoskeleton associations involving four membrane proteins (A5, H58, H36, and I20) were studied in developing L8E63 rat skeletal muscle cells using immunofluorescence microscopy and photometry on the basis of three criteria: Triton-insolubility, colocalization with cytoskeletal components, and sensitivity to cytoskeleton-directed drugs. The results presented demonstrate that there are developmental stage-specific associations between membrane proteins and the cytoskeleton during skeletal myogenesis. Several inconsistencies were found with traditional expectations of membrane-cytoskeleton associations. For example, although A5 is Triton-insoluble and sensitive to cytochalasin, its distribution generally does not correspond with any known cytoskeletal structure. Furthermore, the topography of A5 is dependent on the integrity of the plasma membrane. H36 and I20 are completely soluble in Triton and therefore by accepted definitions would not be expected to be associated with any cytoskeletal component. Yet H36 and actin codisrupt in the presence of cytochalasin, while I20, whose distribution does not correspond with microtubules, is uniquely sensitive to their disruption. These results demonstrate that (i) neither Triton-solubility nor colocalization alone predicts all membrane-cytoskeleton associations; some associations between the membrane and cytoskeleton are unstable in nonionic detergent; (ii) the native distribution of proteins in the membrane may not reflect their cytoskeletal associations; and (iii) the topography of some membrane proteins with no apparent association with the cytoskeleton may be greatly influenced by the cell cytoskeleton.
利用免疫荧光显微镜和光度测定法，基于三个标准：Triton不溶性、与细胞骨架成分共定位以及对细胞骨架导向药物的敏感性，研究了发育中的L8E63大鼠骨骼肌细胞中涉及四种膜蛋白（A5、H58、H36和I20）的质膜-细胞骨架关联。所呈现的结果表明，在骨骼肌生成过程中，膜蛋白与细胞骨架之间存在发育阶段特异性关联。发现了一些与传统的膜-细胞骨架关联预期不一致的情况。例如，尽管A5是Triton不溶性的且对细胞松弛素敏感，但其分布通常与任何已知的细胞骨架结构不对应。此外，A5的拓扑结构取决于质膜的完整性。H36和I20完全可溶于Triton，因此根据公认的定义，预计它们不会与任何细胞骨架成分相关联。然而，在细胞松弛素存在的情况下，H36和肌动蛋白会共同破坏，而I20的分布与微管不对应，它对微管的破坏具有独特的敏感性。这些结果表明：（i）单独的Triton溶解性或共定位都不能预测所有的膜-细胞骨架关联；膜与细胞骨架之间的一些关联在非离子去污剂中是不稳定的；（ii）膜中蛋白质的天然分布可能不反映它们与细胞骨架的关联；（iii）一些与细胞骨架无明显关联的膜蛋白的拓扑结构可能会受到细胞骨架的极大影响。
