Actin filaments in yeast are unstable in the absence of capping protein or fimbrin.
Actin filaments in yeast are unstable in the absence of capping protein or fimbrin.
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DOI：
10.1083/jcb.131.6.1483
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发表时间：
1995-12
期刊：
影响因子：
--
通讯作者：
Cooper JA
中科院分区：
文献类型：
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作者：
Karpova TS;Tatchell K;Cooper JA
许多肌动蛋白结合蛋白在体外影响微丝组装，在体内与肌动蛋白定位，但它们的分子作用如何有助于微丝组装在体内还不清楚。我们在这里报告，加帽蛋白（CP）和fimbryos都是重要的肌动蛋白丝组装在酿酒酵母体内，基于发现减少肌动蛋白丝组装在CP和fimbryos突变体。我们还确定了肌动蛋白的突变，增强CP表型，并发现这些突变体也有减少肌动蛋白丝组装在体内。在体外，从这些突变体中的一些纯化的肌动蛋白是聚合或结合fimmunoglobulin缺陷。这些发现支持CP在体内起稳定肌动蛋白丝的作用的结论。这个结论是特别值得注意的，因为它与最近对网骨藻的研究得出的结论相反（Hug，C.，P.Y.杰伊岛Reddy，J.G. McNally，P.C. Bridgman，E.L. Elson和J.A.库珀。1995. Cell. 81：591-600）。此外，我们发现，在酵母中的肌动蛋白的未聚合池是非常小的，相对于发现在更高的细胞，这表明肌动蛋白丝组装是动态的酵母比更高的细胞。
Many actin-binding proteins affect filament assembly in vitro and localize with actin in vivo, but how their molecular actions contribute to filament assembly in vivo is not understood well. We report here that capping protein (CP) and fimbrin are both important for actin filament assembly in vivo in Saccharomyces cerevisiae, based on finding decreased actin filament assembly in CP and fimbrin mutants. We have also identified mutations in actin that enhance the CP phenotype and find that those mutants also have decreased actin filament assembly in vivo. In vitro, actin purified from some of these mutants is defective in polymerization or binding fimbrin. These findings support the conclusion that CP acts to stabilize actin filaments in vivo. This conclusion is particularly remarkable because it is the opposite of the conclusion drawn from recent studies in Dictyostelium (Hug, C., P.Y. Jay, I. Reddy, J.G. McNally, P.C. Bridgman, E.L. Elson, and J.A. Cooper. 1995. Cell. 81:591-600). In addition, we find that the unpolymerized pool of actin in yeast is very small relative to that found in higher cells, which suggests that actin filament assembly is less dynamic in yeast than higher cells.