Rem2, a new member of the Rem/Rad/Gem/Kir family of Ras-related GTPases
Rem2, a new member of the Rem/Rad/Gem/Kir family of Ras-related GTPases
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DOI：
10.1042/0264-6021:3470223
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发表时间：
2000-04-01
影响因子：
4.1
通讯作者：
Andres, DA
中科院分区：
文献类型：
--
作者：
Finlin, BS;Shao, HP;Andres, DA
在这里，我们报告了 Rem2（Rem、Rad 和 Gem 相关 2）的分子克隆和生化特征，Rem2 是一种新型 GTP 结合蛋白，根据其与 Ras 相关小 GTP 结合蛋白的 Rem、Rad、Gem 和 Kir (RGK) 家族的同源性而被鉴定。在大鼠大脑和肾脏中检测到 Rem2 mRNA，使其成为 RGK 家族中第一个在神经组织中以相对较高水平表达的成员。重组 Rem2 可饱和结合 GTP，并表现出较低的 GTP 水解内在速率。令人惊讶的是，Rem2 和 Rem 的鸟嘌呤核苷酸解离常数与大多数 Ras 相关 GTP 酶显着不同，显示 GTP 的解离速率高于 GDP。使用绿色荧光蛋白 (GFP) 标记的重组蛋白融合体进行的定位研究表明，Rem2 具有点状质膜定位。所有 RGK 家族成员中保守的 C 端 7 个氨基酸残基的缺失不会影响 GFP 融合蛋白的细胞分布，而较大的缺失（包括 Rem2 C 端的大部分多碱基区域）会导致其重新分布到细胞质中。因此，Rem2 是 RGK 家族的一种 GTP 酶，具有独特的生化特性，并拥有新颖的细胞定位信号，与其在细胞生理学中的独特作用一致。
Here we report the molecular cloning and biochemical characterization of Rem2 (for Rem, Rad and Gem-related 2), a novel GTP-binding protein identified on the basis of its homology with the Rem, Rad, Gem and Kir (RGK) family of Ras-related small GTP-binding proteins. Rem2 mRNA was detected in rat brain and kidney, making it the first member of the RGK family to be expressed at relatively high levels in neuronal tissues. Recombinant Rem2 binds GTP saturably and exhibits a low intrinsic rate of GTP hydrolysis. Surprisingly, the guanine nucleotide dissociation constants for both Rem2 and Rem are significantly different than the majority of the Ras-related GTPases, displaying higher dissociation rates for GTP than GDP. Localization studies with green fluorescent protein (GFP)-tagged recombinant protein fusions indicate that Rem2 has a punctate, plasma membrane localization. Deletion of the C-terminal seven amino acid residues that are conserved in all RGK family members did not affect the cellular distribution of the GFP fusion protein, whereas a larger deletion, including much of the polybasic region of the Rem2 C-terminus, resulted in its redistribution to the cytosol. Thus Rem2 is a GTPase of the RGK family with distinctive biochemical properties and possessing a novel cellular localization signal, consistent with its having a unique role in cell physiology.