The Cdc42 GTPase-associated proteins Gic1 and Gic2 are required for polarized cell growth in Saccharomyces cerevisiae
The Cdc42 GTPase-associated proteins Gic1 and Gic2 are required for polarized cell growth in Saccharomyces cerevisiae
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DOI：
10.1101/gad.11.22.2958
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发表时间：
1997-11-15
影响因子：
10.5
通讯作者：
Chan, CSM
中科院分区：
文献类型：
--
作者：
Chen, GC;Kim, YJ;Chan, CSM
酿酒酵母的BEM 2编码Rho型GTP酶激活蛋白，该蛋白是在26 ℃下正确选择芽位和在升高的温度下芽萌发所需的。我们在这里表明，bem 2突变细胞的温度敏感性生长表型可以通过增加GIC 1基因的剂量来抑制。Gic 1蛋白，连同其结构同源物Gic 2，需要细胞的大小和形状控制，芽位点选择，芽的出现，肌动蛋白细胞骨架组织，有丝分裂纺锤体的方向/定位，和交配突起形成交配信息素。每种蛋白质都含有CRIB（Cdc 42/Rac相互作用结合）基序，并且每种蛋白质都在双杂交测定中与Rho型Cdc 42 GTdR的GTP结合形式相互作用，Rho型Cdc 42 GTdR是酵母中极化生长的关键调节因子。Gic 1的CRIB基序和Cdc 42的效应结构域是这种关联所必需的。遗传实验表明，Gic 1和Gic 2在Cdc 42信号转导通路中起着积极的作用，可能是Cdc 42的效应子。亚细胞定位的功能性绿色荧光蛋白Gic 1融合蛋白的研究表明，这种蛋白质是集中在未出芽细胞的初期芽网站，在芽尖和母芽颈出芽细胞，并在皮质网站上的大出芽细胞，可能界定未来的芽网站在两个后代细胞。Gic 1与Cdc 42结合的能力对其功能很重要，但显然对其亚细胞定位不是必需的。
BEM2 of Saccharomyces cerevisiae encodes a Rho-type GTPase-activating protein that is required for proper bud site selection at 26 degrees C and for bud emergence at elevated temperatures. We show here that the temperature-sensitive growth phenotype of bem2 mutant cells can be suppressed by increased dosage of the GIC1 gene. The Gic1 protein, together with its structural homolog Gic2, are required for cell size and shape control, bud site selection, bud emergence, actin cytoskeletal organization, mitotic spindle orientation/ positioning, and mating projection formation in response to mating pheromone. Each protein contains a CRIB (Cdc42/Rac-interactive binding) motif and each interacts in the two-hybrid assay with the GTP-bound form of the Rho-type Cdc42 GTPase, a key regulator of polarized growth in yeast. The CRIB motif of Gic1 and the effector domain of Cdc42 are required for this association. Genetic experiments indicate that Gic1 and Gic2 play positive roles in the Cdc42 signal transduction pathway, probably as effecters of Cdc42. Subcellular localization studies with a functional green fluorescent protein-Gic1 fusion protein indicate that this protein is concentrated at the incipient bud site of unbudded cells, at the bud tip and mother-bud neck of budded cells, and at cortical sites on large-budded cells that may delimit future bud sites in the two progeny cells. The ability of Gic1 to associate with Cdc42 is important for its function but is apparently not essential for its subcellular localization.