内部核糖体进入位点介导核糖体翻译起始机制  

Internal Ribosomal Entry Site Induced Mechanism of Translation Initiation in the Ribosome

作　　者：马鹏[1,2] 周小凯[1,2] 常秋燕 李林杰[1,2] 马晓霞[1,2] 马忠仁[1,2] MA Peng ZHOU Xiao-kai CHANG Qiu-yan LI Lin-jie MA Xiao-xia MA Zhong-ren(Gansu Engineering Research Center For Animal Cell, Northwest Minzu University, Lanzhou, Gansu, 730030, China College of Life Sciences and Engineering, Northwest Minzu University, Lanzhou ,Gansu, 730030, China)

机构地区：[1]西北民族大学甘肃省动物细胞工程技术研究中心,甘肃兰州730030 [2]西北民族大学生命科学与工程学院,甘肃兰州730030

出　　处：《动物医学进展》2017年第6期74-78,共5页Progress In Veterinary Medicine

基　　金：企业横向项目(XBMu-2015-Bc-11);中央高校基本科研业务费(1001860564)

摘　　要：部分正链RNA病毒基因的蛋白质合成是由其自身的内部核糖体进入位点(internal ribosomal entry site,IRES)以非依赖5’甲基化帽状结构来实现的。目前,IRES被分为4类,虽然这4类IRES在对其介导的基因合成目的蛋白的机制不同,但是这些不同蛋白翻译机制是依赖IRES与不同真核翻译起始因子相互作用形成特定的复合物来实现的。真核生物翻译是由起始tRNA(Met-tRNAMeti)/eIF2·GTP三元复合物引发,与翻译因子和40S小亚基结合形成43S复合物,43S复合物在eIF1A协助下与起始密码子结合形成48S复合物,在eIF5·GTP促进下60S亚基与40S亚基结合形成80S核糖体。IRES介导翻译通过eIF4G、IRES与eIF4A结合引导43S复合物与IRES结合。Ⅲ型IRES在无eIF3的参与下与40S小亚基的E位点结合并与eIF2·GTP/initiator tRNA形成48S亚基,在eIF5/eIF5B的调控下与60S亚基形成活化的核糖体进行蛋白质翻译。The protein synthesis of RNA viral genes is realized by the internal ribosomal entry site（IRES）, which is independent on the 5 methylation cap structure.At present, IRES is divided into four categories, although the four types of IRES are different in the mechanism of gene synthesis of the target protein.The translation mechanism of these proteins is dependent on the interaction of IRES with different eukaryotic translation initiation factors to form specific complexes.Eukaryotic translation was initiated by the tRNA （Met-tRNAMeti）/eIF2 · GTP ternary complex, which binds to the translation factor and the 40S subunit to form a 43S complex that in eIFIA assistance and initiation codon to form 48S complexes. In the end, with eIF5 · GTP promoted the formation of 80S ribosome through combination of 60S subunit and 40S subunit.IRES-mediated translation through the combination of eIF4G, IRES and eIF4A guide the combination of 43S complex and IRES. Type 3 IRESs combined in E-sites of 40S subunit without the eIF3, afterwards combined with eIF2 · GTP/initiator tRNA constitute a 48S complex. The 48S complex in an eIF5/ eIF5B mediated reaction to come into being a 60S subunit which form an active ribosome that can turn on the protein translation.

关 键 词：核糖体 内部核糖体进入位点 蛋白质翻译起始 Ⅲ型内部核糖体进入位点 

分 类 号：S852.2[农业科学—基础兽医学]