CONTRIBUTION OF ACTIN TO THE STRUCTURE OF THE CYTOPLASMIC MATRIX
CONTRIBUTION OF ACTIN TO THE STRUCTURE OF THE CYTOPLASMIC MATRIX
复制标题
DOI：
10.1083/jcb.99.1.15s
复制
发表时间：
1984-01-01
影响因子：
7.8
通讯作者：
STOSSEL, TP
中科院分区：
文献类型：
--
作者：
STOSSEL, TP
认识到肌动蛋白是非肌肉细胞的一个组成部分(1)，以及在这些细胞的外围发现肌动蛋白丝(2)，开辟了分子生物学的一个新世界。这是第一次有可能详细解释两个世纪以来描述的关于细胞形状、运动和一致性的重要方面的一系列现象。虽然肌动蛋白只是细胞内几个纤维系统中的一个，但它是一个极其重要的系统。本文简要回顾了目前有关肌动蛋白对细胞质基质的贡献的一些概念。对肌动蛋白在非肌肉细胞中的存在的认识，立即提供了一些关于这些细胞行为的直观的有吸引力的想法。首先，肌动蛋白是一种球形单体，可以可逆地组装形成长纤维，这种组装增加了肌动蛋白溶液的表观粘度(3)。因此，细胞不同部分组装状态的变化可以解释细胞质一致性的差异。其次，长肌动蛋白纤维，如果足够坚硬，特别是如果组织成束，可以保持细胞或细胞部分的特定结构。第三，肌动蛋白与肌凝蛋白共同作用，可以产生在这些细胞中观察到的收缩性。第四，肌动蛋白纤维可以像电缆一样将细胞的各个部分，包括它的投资膜，连接在一起。这四个关于肌动蛋白纤维的“机械”特性的基本观点，在其最广泛的意义上仍然是有效的。然而，很明显，受看似无穷无尽的“肌动蛋白结合蛋白”的影响，factin的功能异常复杂。虽然这种复杂性乍一看似乎令人生畏和困惑，但它实际上证明了这种高度保守的蛋白质的惊人的多功能性，也证明了大自然在细胞质工程方面的独创性。肌动蛋白在细胞质结构和功能方面的研究在两个方面取得了进展。一方面，研究人员在体外研究肌动蛋白组装和流变的细节，以及纯化的肌动蛋白相关蛋白对这些特性的影响。粗细胞质提取物的流变学特性往往为这类研究提供了方向。另一方面，细胞生物学家在光线和电子显微镜下检查细胞中肌动蛋白的形态，并确定肌动蛋白相关蛋白在细胞中的位置。
The realization that actin is a constituent of nonmuscle cells (1) and the identification of actin filaments in the periphery ofsuch cells (2) opened up a new world ofmolecular biology. For the first time it became possible to explain in detail a body of phenomena described over two centuries concerning important aspects of cell shape, movement, and consistency. Although actin comprises only one of several intracellular fiber systems of cells, it is an extremely important one. This essay briefly reviews some present concepts of the contribution of actin to the" cytoplasmic matrix." The appreciation of actin's existence in nonmuscle cells immediately provided some intuitively attractive ideas concerning the behavior of such cells. First, actin is a globular monomer that assembles reversibly to form long fibers, and this assembly increases the apparent viscosity of an actin solution (3). Therefore, changes in the state of assembly in different parts of a cell could account for differences in cytoplasmic consistency. Second, long actin fibers, if sufficiently stiff and especially if organized as bundles, could maintain the cell or parts of cells in a particular configuration. Third, actin, working together with myosin, could generate the contractility observed in these cells. Fourth, actin fibers could act as cables to tie parts ofthe cell, including its investing membrane, together. These four basic ideas, which concern" mechanical" properties of actin fibers, continue in their broadest sense to be valid. However, it has become apparent that the functions ofactin, influenced by a seemingly endless number of" actin-binding proteins," are extraordinarily complex. Although this complexity seems formidable and confusing at first glance, it actually is a testimony to the marvellous versatility of this highly conserved protein (4) and to nature's ingenuity in the engineering ofcytoplasm. Research on actin in cytoplasmic structure and function has been advancing on two fronts. On one, investigators study the details of actin assembly and rheology in vitro and the influence of purified actin-associated proteins on these properties. The rheological behavior ofcrude cytoplasmic extracts has often provided the direction for such research. On the other, cell biologists examine the morphology ofactin in cells in the light and the electron microscope and also determine the location of the actin-associated proteins in the cell.