Semler Bert L, Waterman Marian L
Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA.
Trends Microbiol. 2008 Jan;16(1):1-5. doi: 10.1016/j.tim.2007.11.001.
Eukaryotic mRNA initiates translation by cap-dependent scanning, ribosome shunting and cap-independent internal ribosome entry. Internal ribosome entry was first discovered for cytoplasmic RNA viruses but has also been identified for DNA viruses and cellular mRNAs. An internal ribosome entry site (IRES) directs internal binding of ribosomes and nucleates the formation of a translation initiation complex. Current research is aimed at identifying interactions between IRES elements and RNA-binding proteins known as ITAFs (IRES trans-acting factors). Here we compare IRES elements from cytoplasmic RNA viruses with those of cellular mRNAs and DNA viruses with nuclear mRNA synthesis, and suggest that ITAF composition and IRES function directly reflect the site of synthesis of mRNA and the history of its pathway to polysomes.
真核生物的信使核糖核酸（mRNA）通过依赖帽子结构的扫描、核糖体跳跃和不依赖帽子结构的内部核糖体进入来启动翻译。内部核糖体进入最初是在细胞质RNA病毒中发现的，但在DNA病毒和细胞mRNA中也已被鉴定出来。一个内部核糖体进入位点（IRES）指导核糖体的内部结合，并促使翻译起始复合物的形成。当前的研究旨在确定IRES元件与被称为ITAFs（IRES反式作用因子）的RNA结合蛋白之间的相互作用。在这里，我们将细胞质RNA病毒的IRES元件与细胞mRNA的IRES元件进行比较，并将DNA病毒的IRES元件与核mRNA合成进行比较，结果表明ITAF的组成和IRES的功能直接反映了mRNA的合成位点及其通向多核糖体途径的历史。
