Intermediates in the Guanine Nucleotide Exchange Reaction of Rab8 Protein Catalyzed by Guanine Nucleotide Exchange Factors Rabin8 and GRAB
Intermediates in the Guanine Nucleotide Exchange Reaction of Rab8 Protein Catalyzed by Guanine Nucleotide Exchange Factors Rabin8 and GRAB
复制标题
鸟嘌呤核苷酸交换因子 Rabin8 和 GRAB 催化 Rab8 蛋白鸟嘌呤核苷酸交换反应的中间体
DOI：
10.1074/jbc.m113.498329
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发表时间：
2013-11-08
影响因子：
4.8
通讯作者：
Itzen, Aymelt
中科院分区：
文献类型：
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作者：
Guo, Zhong;Hou, Xiaomin;Itzen, Aymelt
RAS超家族的小G蛋白作为分子的开/关开关，控制细胞内信号网络的时空协调。鸟嘌呤核苷酸交换因子(GEF)通过催化GTP取代GDP来调节这些G蛋白的激活。在核苷酸交换过程中，产生了三种不同的底物酶复合体：反应开始时与GDP的三元复合体(G-Protein GEFGDP)，中间无核苷酸的二元复合体(G-Protein Gem)，以及生产性G-蛋白激活后的三元GTP复合体(G-Protein GEFGTP)。在这里，我们展示了完整的核苷酸交换反应序列的结构快照，以及G蛋白底物和产物，使用Rabin8/Grab(全球环境基金)和Rab8(G蛋白)作为模型系统。结合彻底的酶特性，我们的数据为Rabin8/Grab介导的核苷酸交换机制提供了详细的观点。
Small G-proteins of the Ras superfamily control the temporal and spatial coordination of intracellular signaling networks by acting as molecular on/off switches. Guanine nucleotide exchange factors (GEFs) regulate the activation of these G-proteins through catalytic replacement of GDP by GTP. During nucleotide exchange, three distinct substrateenzyme complexes occur: a ternary complex with GDP at the start of the reaction (G-proteinGEFGDP), an intermediary nucleotide-free binary complex (G-proteinGEF), and a ternary GTP complex after productive G-protein activation (G-proteinGEFGTP). Here, we show structural snapshots of the full nucleotide exchange reaction sequence together with the G-protein substrates and products using Rabin8/GRAB (GEF) and Rab8 (G-protein) as a model system. Together with a thorough enzymatic characterization, our data provide a detailed view into the mechanism of Rabin8/GRAB-mediated nucleotide exchange.