中文摘要：

RNA沉默是由小RNA特异向导和RNA诱导的沉默复合物（RISC）切割或者抑制靶标mRNA翻译的一种调控系统.作为RISC的核心成分,AGO蛋白（argonaute proteins）由N末端、PAZ、MID和PIWI4个结构域组成.PAZ区能非序列特异性识别结合双链小RNA3′末端悬垂的2个核苷酸,MID与PIWI界面处的＂保守口袋＂识别结合小RNA5′端第1位核苷酸,PIWI区具有切割mRNA的催化中心.根据系统进化学分析,AGO蛋白家族分为3个组：AGO-like、PIWI-like和GROUP3.拟南芥共编码10种AGO蛋白.目前已经证实,具有切割活性的为AtAGO1、AtAGO4和AtAGO7,三者参与的小RNA通路也已得到确认.在拟南芥10种AGO蛋白中,AtAGO1与AtAGO10、AtAGO1与AtAGO7、AtAGO4与AtAGO6存在功能上的部分冗余.

英文摘要：

RNA silencing is a kind of cellular regulating system for mRNA cleavage or translation repression mediated by RNA induced silencing complex（RISC）under sequence-specific direction of small RNAs.As the core component of RISC,AGO（argonaute）protein consists of four domains：N terminus,PAZ,MID and PIWI.PAZ domain recognizes and binds 3＇ terminal 2 nt overhang of small RNA duplex non-sequence-specifically.＇Conserved pocket＇ located at the interface between MID and PIWI recognizes and binds the first nucleotide of 5＇ terminus of small RNA.PIWI domain has a catalytic center for mRNA cleavage.According to the phylogenetic analysis,AGO family is divided into three groups：AGO-like,PIWI-like and GROUP3.Arabidopsis encodes ten AGO proteins（AtAGOs 1-10）.Amongst,AtAGOs 1,4 and 7 have been identified to possess cleavage acitivy,and to be involved in some small RNA pathways.In addition,partially functional redundancy exists between AtAGO1 and AtAGO10,AtAGO1 and AtAGO7,and AtAGO4 and AtAGO6.