ACTIN ASSOCIATED WITH MEMBRANES FROM 3T3 MOUSE FIBROBLAST AND HELA-CELLS
ACTIN ASSOCIATED WITH MEMBRANES FROM 3T3 MOUSE FIBROBLAST AND HELA-CELLS
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DOI：
10.1083/jcb.64.1.223
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发表时间：
1975-01-01
影响因子：
7.8
通讯作者：
WEIHING, RR
中科院分区：
文献类型：
--
作者：
GRUENSTEIN, E;RICH, A;WEIHING, RR
从3T3小鼠成纤维细胞和HeLa细胞膜中分离出一种蛋白质组分，通过肽图谱鉴定为肌动蛋白。与鸡骨骼肌肌动蛋白相比，这两种非肌膜相关肌动蛋白的肽图有广泛的一致性，但显然并不完全一致。在3T3膜的十二烷基硫酸钠-聚丙烯酰胺凝胶上，约有2%~4%的膜蛋白出现在肌动蛋白带中，而在HeLa膜上，约有4%的膜蛋白出现在肌动蛋白带中。这些值代表了细胞匀浆中肌动蛋白占总蛋白的大致相同的比例。在3T3或HeLa细胞中，细胞松弛素B水平足以引起明显的形态变化的完整细胞的处理并没有改变与细胞膜相关的肌动蛋白的量。然而，在有利于肌动蛋白从丝状转化为单体的条件下孵育分离的膜，分别导致约80%和60%的肌动蛋白从3T3和HeLa膜上解离。因此，即使在肌动蛋白解聚的条件下，大约20%的3T3膜肌动蛋白和40%的HeLa膜肌动蛋白仍然与膜相关。Actin现在已经被鉴定为几乎所有寻找它的真核动物细胞的组成部分。此外，在许多非肌肉细胞中发现了肌球蛋白和原肌球蛋白样蛋白。(最近出现了一篇关于非肌肉细胞收缩蛋白的广泛综述[29]。在几种电子显微镜制备中，已在原位(24、36、42、44、45)或在分离的质膜(28)中观察到质膜与肌动蛋白细丝(或大小为肌动蛋白的细丝)之间的明显接触。也有生化证据表明，肌动蛋白与多种细胞因子有关。
A protein component of membranes isolated from 3T3 mouse fibroblasts and HeLa cells has been identified as actin by peptide mapping. Extensive but apparently not total coincidence was found between the peptide maps of these two nonmuscle membrane-associated actins compared to chick skeletal muscle actin. Between 2 and 4% of the total membrane protein appears in the actin band on sodium dodecyl sulfate polyacrylamide gels of 3T3 membranes while about 4% of the membrane protein appears as the actin band from HeLa membranes. These values represent approximately the same proportion of actin to total protein found in the cell homogenates. Treatment of intact cells with levels of cytochalasin B sufficient to cause pronounced morphological changes did not change the amount of actin associated with the membrane in either 3T3 or HeLa cells. However, incubation of isolated membranes under conditions favoring conversion of actin from filamentous to monomeric form resulted in dissociation of approximately 80 and 60% of the actin from 3T3 and HeLa membranes, respectively. Thus, approximately 20% of 3T3 membrane actin and 40% of HeLa membrane actin remained associated with the membrane even under actin depolymerizing conditions.Actin has now been identified as a component of essentially all eukaryotic animal cells in which it has been sought. In addition, myosin-and tropomyosin-like proteins have been identified in many of these nonmuscle cells.(An extensive review on the subject of contractile proteins of nonmuscle cells has recently appeared [29].) In several electron microscope preparations, apparent contact between plasma membrane and actin filaments (or thin filaments with the dimensions of actin) has been observed in situ (24, 36, 42, 44, 45) or in isolated plasma membranes (28). Biochemical evidence has also been presented that actin is associ-