Repressor binding to a dorsal regulatory site traps human elF4E in a high cap-affinity state
Repressor binding to a dorsal regulatory site traps human elF4E in a high cap-affinity state
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DOI：
10.1093/emboj/18.14.4068
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发表时间：
1999-07-15
期刊：
影响因子：
11.4
通讯作者：
McCarthy, JEG
中科院分区：
文献类型：
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作者：
Ptushkina, M;von der Haar, T;McCarthy, JEG
真核翻译起始涉及到被称为真核起始因子 4F (eIF4F) 的帽子结合复合物对细胞 mRNA 5' 端的识别，起始是响应信号转导途径介导的机制而调节基因表达的关键点。我们研究了称为 4E 结合蛋白 (4E-BP) 的可调节阻遏物抑制人类 eIF4E 功能的分子相互作用。eIF4F 的两个基本成分是帽结合蛋白 eIF4E 和 eIF4G（一种结合 eIF4E 和其他必需 eIF 的多功能蛋白）。我们发现 4E-BP 1 和 2 通过竞争与eIF4E 上的背侧位点，值得注意的是，4E-BP 在该背侧位点的结合增强了通过腹侧帽结合槽的帽结合，从而将 eIF4E 捕获在对带帽 mRNA 具有高亲和力的非活性复合物中，4E-BP1/2 和 eIF4E 之间相互作用的结合接触和亲和力是不同的（估计 K-d 值为 10(-8) 和 3 x 10(-9)分别为 4E-BP1 和 2），这些特性的差异由保守基序内的三个氨基酸决定。这些数据为翻译调控的新分子模型提供了定量框架。
Eukaryotic translation initiation involves recognition of the 5' end of cellular mRNA by the cap-binding complex known as eukaryotic initiation factor 4F (eIF4F), Initiation is a key point of regulation in gene expression in response to mechanisms mediated by signal transduction pathways. We have investigated the molecular interactions underlying inhibition of human eIF4E function by regulatable repressors called 4E-binding proteins (4E-BPs), Two essential components of eIF4F are the cap-binding protein eIF4E, and eIF4G, a multi-functional protein that binds both eIF4E and other essential eIFs, We show that the 4E-BPs 1 and 2 block the interaction between eIF4G and eIF4E by competing for binding to a dorsal site on eIF4E, Remarkably, binding of the 4E-BPs at this dorsal site enhances cap-binding via the ventral cap-binding slot, thus trapping eIF4E in inactive complexes with high affinity for capped mRNA, The binding contacts and affinities for the interactions between 4E-BP1/2 and eIF4E are distinct (estimated K-d values of 10(-8) and 3 x 10(-9) for 4E-BP1 and 2, respectively), and the differences in these properties are determined by three amino acids within an otherwise conserved motif, These data provide a quantitative framework for a new molecular model of translational regulation.