What are the basic functions of microfilaments? Insights from studies in budding yeast.
What are the basic functions of microfilaments? Insights from studies in budding yeast.
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DOI：
10.1083/jcb.126.4.821
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发表时间：
1994-08
期刊：
影响因子：
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通讯作者：
Wang T
中科院分区：
文献类型：
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作者：
Bretscher A;Drees B;Harsay E;Schott D;Wang T
25年前，人们发现f -肌动蛋白是动物细胞微丝的主要成分（36）。从那时起，肌动蛋白几乎在所有真核细胞中都被发现。微丝有什么功能？动物细胞的研究为我们提供了一幅f -肌动蛋白的图像，它是任何给定细胞内共存的许多结构和功能不同的组装体的骨干。微丝对细胞的形状决定、细胞运动和各种收缩活动，以及参与跨膜信号传导、内吞作用和分泌等方面都很重要。由于一些肌动蛋白结合蛋白通过游离Ca:+、磷脂和磷酸化的变化来调节（75），微丝组织可以通过小g蛋白来调节（69,70），因此微丝似乎处于精细的控制之下。此外，最近发现一些肌动蛋白结合蛋白含有SI-I2和SH3结构域（56），这表明微丝被整合到蛋白-蛋白信号通路中。考虑到这些多样化和复杂的调控系统，我们对微丝的精确功能的了解差距更令人沮丧。酿酒酵母（Saccharomyces cerevisiae）是近年来研究微丝功能的研究热点。为什么?酵母细胞不运动，细胞壁坚硬，不易变形，没有明显的表面结构。因此，微丝在脊椎动物细胞中发挥的一些作用在酵母中没有发现，但微丝是至关重要的，因为酵母含有一个必需的肌动蛋白基因（73）。酵母细胞周期中f -肌动蛋白分布的调节是微丝可能在细胞形态发生中发挥作用的第一个迹象（41）；也就是说，靶向分泌囊泡用于子细胞的组装，而不是为子细胞提供基础设施。这立即引发了一系列问题：f -肌动蛋白的分布是如何确定的，构成这些微丝状结构的成分是什么，它们的功能是什么？基因鉴定和分析功能相关成分的方法相对容易，再加上近乎宗教信仰的信念，即酿酒链球菌适用的方法基本上也适用于智人，推动了这种流行。这篇评论试图传达这样一种观点，即亲属
WENTY-FIVE years ago, F-actin was discovered to be the major component of microfilaments in animal cells (36). Since then, actin has been found in virtually all eukaryotic cells. What functions do microfilaments perform? Studies in animal cells have provided us with a picture of F-actin as the backbone of many structurally and functionally diverse assemblies coexisting within any given cell. Microfilaments are important for cell shape determination, cell motility, and various contractile activities, as well as for participating in aspects of transmembrane signaling, endocytosis, and perhaps secretion. Since some actin-binding proteins are regulated by changes in free Ca:+, phospholipids, and by phosphorylation (75), and microfilament organizations can be modulated by small G-proteins (69, 70), microfilaments seem to be under exquisite control. Moreover, recent discoveries that some actin-binding proteins contain SI-I2 and SH3 domains (56) suggest that microfilaments are integrated into protein-protein signaling pathways. Given these diverse and sophisticated regulatory systems, the gap in our knowledge of the precise functions performed by microfilaments is all the more distressing. The budding yeast Saccharomyces cerevisiae has recently become very popular for studying the function of microfilaments. Why? Yeast cells are nonmotile and they have a rigid cell wall, do not change shape rapidly, and have no obvious surface structures. Therefore, some of the roles that microfilaments play in vertebrate cells are not seen in yeast, yet microfilaments are vital because yeast contains a single essential actin gene (73). The regulation of F-actin distribution during the cell cycle in yeast was the first indication that microfilaments might play a role in cellular morphogenesis (41); that is, in the targeting of secretory vesicles for the assembly of the daughter cell rather than providing an infrastructure for it. This immediately raised a number of questions: how is the distribution of F-actin determined, what are the components that make up these microfilamentous structures, and what are their functions? The relative ease of genetic approaches for the identification and analysis of functionally related components, together with the near religious belief that what is true for S. cerevisiae is also fundamentally true for Homo sapiens, has driven this popularity. This review seeks to convey the view that the relative