Pestova T V, Borukhov S I, Hellen C U
Department of Microbiology and Immunology, State University of New York Health Science Center at Brooklyn, 11203, USA.
Nature. 1998 Aug 27;394(6696):854-9. doi: 10.1038/29703.
The scanning model of translation initiation is a coherent description of how eukaryotic ribosomes reach the initiation codon after being recruited to the capped 5' end of messenger RNA. Five eukaryotic initiation factors (eIF 2, 3, 4A, 4B and 4F) with established functions have been assumed to be sufficient to mediate this process. Here we report that eIF1 and eIF1A are also both essential for translation initiation. In their absence, 43S ribosomal preinitiation complexes incubated with ATP, eIF4A, eIF4B and eIF4F bind exclusively to the cap-proximal region but are unable to reach the initiation codon. Individually, eIF1A enhances formation of this cap-proximal complex, and eIF1 weakly promotes formation of a 48S ribosomal complex at the initiation codon. These proteins act synergistically to mediate assembly of ribosomal initiation complexes at the initiation codon and dissociate aberrant complexes from the mRNA.
翻译起始的扫描模型是对真核核糖体在被招募到信使核糖核酸（mRNA）的5' 端帽状结构后如何到达起始密码子的连贯描述。人们认为具有既定功能的五种真核起始因子（eIF 2、3、4A、4B和4F）足以介导这一过程。在此我们报告，eIF1和eIF1A对翻译起始也都是必不可少的。在缺乏它们的情况下，与ATP、eIF4A、eIF4B和eIF4F一起孵育的43S核糖体前起始复合物仅与帽近端区域结合，但无法到达起始密码子。单独来看，eIF1A增强了这种帽近端复合物的形成，而eIF1则在起始密码子处微弱地促进48S核糖体复合物的形成。这些蛋白质协同作用，介导核糖体起始复合物在起始密码子处的组装，并使异常复合物从mRNA上解离。
