Essential Role of the NH2-Terminal Region of Cdc24 Guanine Nucleotide Exchange Factor in Its Initial Polarized Localization in Saccharomyces cerevisiae
Essential Role of the NH2-Terminal Region of Cdc24 Guanine Nucleotide Exchange Factor in Its Initial Polarized Localization in Saccharomyces cerevisiae
复制标题
Cdc24 鸟嘌呤核苷酸交换因子的 NH2 末端区域在酿酒酵母初始极化定位中的重要作用
作者：
Fujimura-Kamada K;Hirai T;Tanaka K
小GTPase Cdc42的皮质募集和积累是极性建立的关键步骤，但这一过程尚不清楚。Cdc24是出芽酵母Cdc42的上游调节剂，通过其Dbl同源性（DH）结构域加速Cdc42中GTP与GDP的交换。在这里，我们分离了五个新的温度敏感（ts）cdc24突变体，其中绿色荧光蛋白（GFP）融合蛋白在不允许的温度下失去其极化定位。突变体中的所有氨基酸替换都被定位到Cdc24的nh2末端区域，包括钙钙蛋白同源性（CH）结构域。这些Cdc24-ts突变蛋白在cooh末端PB1结构域不与Bem1相互作用，这表明突变蛋白中缺乏PB1结构域的暴露。在缺乏Bem1的情况下，dc24突变体的极化也存在缺陷。先前有报道称，含有Cdc24和p21活化激酶（PAK）样激酶Cla4的融合蛋白可以在极性线索不依赖的出芽（即对称破缺）中绕过Bem1的要求。cdc24 -ts - cl4融合蛋白在极性位点也显示出ts定位。我们提出，nh2末端区域揭开DH和PB1结构域，分别导致Cdc42的激活和与Bem1的相互作用，从而启动细胞极化。
The cortical recruitment and accumulation of the small GTPase Cdc42 are crucial steps in the establishment of polarity, but this process remains obscure. Cdc24 is an upstream regulator of budding yeast Cdc42 that accelerates the exchange of GDP for GTP in Cdc42 via its Dbl homology (DH) domain. Here, we isolated five novel temperature-sensitive (ts)cdc24mutants, the green fluorescent protein (GFP)-fused proteins of which lose their polarized localization at the nonpermissive temperature. All amino acid substitutions in the mutants were mapped to the NH2-terminal region of Cdc24, including the calponin homology (CH) domain. These Cdc24-ts mutant proteins did not interact with Bem1 at the COOH-terminal PB1 domain, suggesting a lack of exposure of the PB1 domain in the mutant proteins. Thecdc24-tsmutants were also defective in polarization in the absence of Bem1. It was previously reported that a fusion protein containing Cdc24 and the p21-activated kinase (PAK)-like kinase Cla4 could bypass the requirement for Bem1 in polarity cue-independent budding (i.e., symmetry breaking). Cdc24-ts–Cla4 fusion proteins also showed ts localization at the polarity site. We propose that the NH2-terminal region unmasks the DH and PB1 domains, leading to the activation of Cdc42 and interaction with Bem1, respectively, to initiate cell polarization.
登录
查看更多内容
影响因子：
56.9
作者：
Butty, AC;Pryciak, PM;Peter, M
通讯作者：
Peter, M
双脱氧链终止法手动和自动 DNA 测序概述
影响因子：
4.8
作者：
E. Chen;W. Kuang;Angela L. Lee
通讯作者：
Angela L. Lee
影响因子：
2.7
作者：
R. Elble
通讯作者：
R. Elble
影响因子：
3.3
作者：
P. James;J. Halladay;E. Craig
通讯作者：
P. James;J. Halladay;E. Craig
Cdc50p 是一种保守的内体膜蛋白，控制酿酒酵母的极化生长
DOI：
--
发表时间：
2003
期刊：
Molecular Biology of the Cell 14
影响因子：
--
作者：
斉藤 康二;三栖 賢次郎
通讯作者：
三栖 賢次郎