Switch-domain mutations in the Saccharomyces cerevisiae G protein alpha-subunit Gpa1p identify a receptor subtype-biased mating defect.
Switch-domain mutations in the Saccharomyces cerevisiae G protein alpha-subunit Gpa1p identify a receptor subtype-biased mating defect.
复制标题
酿酒酵母 G 蛋白 α 亚基 Gpa1p 中的开关域突变可识别受体亚型偏向的交配缺陷。
DOI：
10.1007/s004380050695
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Kurjan,J
中科院分区：
文献类型：
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作者：
DeSimone,SM;Kurjan,J
酿酒酵母对信息素的响应涉及一种由Gpa1p （α亚基）、Ste4p （β）和Ste18p （γ）组成的异源三聚体G蛋白。Gα亚基的开关II区参与多种蛋白质-蛋白质相互作用和内在的GTPase活性。为了研究Gpa1p的这一区域的作用，我们分析了开关II突变的影响。Gα亚基和Ras中的Q323类似物与GTP水解有关。Gpa1p Q323残基的突变导致信息素反应途径的组成性激活，并消除了与Ste4p相互作用的能力，这与GTPase活性缺陷一致。Ras残基A59的突变与类似的g - αs残基的突变效果大不相同。类似的Gpa1p G321T突变导致的表型与较轻的GTPase缺陷一致，但也导致了意想不到的交配表型：两种交配类型的交配都减少，但α细胞中的缺陷比非细胞严重1000倍。此外，G321T突变导致不寻常的信息素反应表型。我们讨论了这些表型可能反映了开关II区在thea-和α-因子受体激活中的不同作用的可能性。
The response to pheromone inSaccharomyces cerevisiaeinvolves a heterotrimeric G protein composed of Gpa1p (α subunit), Ste4p (β) and Ste18p (γ). The switch II region of Gα subunits is involved in several protein-protein interactions and an intrinsic GTPase activity. To investigate the role of this region of Gpa1p, we have analyzed the effect of switch II mutations. The Q323 analog in Gα subunits and Ras is implicated in GTP hydrolysis. Mutation of the Q323 residue of Gpa1p resulted in constitutive activation of the pheromone response pathway and eliminated the ability to interact with Ste4p, consistent with a defect in GTPase activity. Mutation of residue A59 of Ras and the analogous Gαs residue has had quite different effects. The analogous Gpa1p G321T mutation resulted in phenotypes consistent with a less severe GTPase defect, but also led to an unexpected mating phenotype: mating was decreased in both mating types, but the defect was 1000-fold more severe in α cells than inacells. In addition the G321T mutation resulted in an unusual pheromone response phenotype. We discuss the possibility that these phenotypes may reflect a differential role for the switch II region in activation by thea- and α-factor receptors.