Localization of Ras signaling complex in budding yeast
Localization of Ras signaling complex in budding yeast
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DOI：
10.1016/j.bbamcr.2012.04.016
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发表时间：
2012-07-01
影响因子：
5.1
通讯作者：
Martegani, Enzo
中科院分区：
文献类型：
--
作者：
Belotti, Fiorella;Tisi, Renata;Martegani, Enzo
在酿酒酵母中，cAMP/PKA途径在代谢、抗逆和增殖控制中起着重要作用。CAMP是由腺苷环化酶产生的，它由Gpr1/Gpa2系统和Ras蛋白激活，受CDC25/Sdc25鸟嘌呤交换因子和Ira GTP酶激活蛋白调节。最近研究发现，Ras2和CDC25不仅存在于细胞质膜，也存在于细胞内膜。在这里，通过荧光标记和蔗糖梯度上的生化细胞膜分级来研究RAS信号复合蛋白的亚细胞定位。尽管在葡萄糖的指数生长过程中，质膜上持续存在少量的RAS信号复合体成分，但CDC25似乎主要定位在内质网膜上，而IRA2和Cyr1也明显存在于线粒体上。此外，PKA Tpk1催化亚基的过表达诱导IRA2蛋白从线粒体移动到内质网。这些数据证实了这样的假设，即RAS信号通路的不同分支可能涉及不同的亚细胞室，并且RAS信号复杂成分的重新定位受PKA控制。(C)2012爱思唯尔B.V.保留所有权利。
In Saccharomyces cerevisiae, cAMP/pKA pathway plays a major role in metabolism, stress resistance and proliferation control. cAMP is produced by adenylate cyclase, which is activated both by Gpr1/Gpa2 system and Ras proteins, regulated by Cdc25/Sdc25 guanine exchange factors and Ira GTPase activator proteins. Recently, both Ras2 and Cdc25 RasGEF were reported to localize not only in plasma membrane but also in internal membranes. Here, the subcellular localization of Ras signaling complex proteins was investigated both by fluorescent tagging and by biochemical cell membrane fractionation on sucrose gradients. Although a consistent minor fraction of Ras signaling complex components was found in plasma membrane during exponential growth on glucose, Cdc25 appears to localize mainly on ER membranes, while Ira2 and Cyr1 are also significantly present on mitochondria. Moreover, PKA Tpk1 catalytic subunit overexpression induces Ira2 protein to move from mitochondria to ER membranes. These data confirm the hypothesis that different branches of Ras signaling pathways could involve different subcellular compartments, and that relocalization of Ras signaling complex components is subject to PKA control. (C) 2012 Elsevier B.V. All rights reserved.