肽链释放因子识别终止密码子的机制

肽链释放因子(polypeptide release factor, RF)是参与细胞内蛋白质合成终止过程中新生肽链释放的一组重要的蛋白质，包括两类，即第一类肽链释放因子(classⅠrelease factor, RFⅠ)和第二类肽链释放因子(classⅡrelease factor, RFⅡ).关于第一类肽链释放因子识别终止密码子的机制和功能位点是目前分子细胞生物学领域的一个研究热点，第二类肽链释放因子作为一类GTP酶，在第一类肽链释放因子识别终止密码子和肽链释放过程中的协同作用也备受关注.近些年来，通过构建体内和体外的测活体系，对第一类肽链释放因子识别终止密码子的机制的研究取得了一些进展，提出了多种假说和模型，尤其是对第一类肽链释放因子的晶体结构及两类肽链释放因子复合体的空间结构的研究，为揭示真核生物细胞内蛋白质合成终止机制提供了直接的证据.

Stop Codon Recognition Mechanism of the Polypeptide Release Factors

Polypeptide release factor (RF) is a kind of important proteins involved in the termination of protein biosynthesis in cell. Two types RFs have been described，one is classⅠrelease factor (RF-Ⅰ) responsible for stop codon recognition; other is codon non-specific classⅡrelease factor (RF-Ⅱ). The study on the stop codon recognition mechanism and functional sites of RF-Ⅰbecome one of research hotspots in the area of molecular and cellular biology. At the same time, the role of RF-Ⅱwhich acts as GTPase is also attractive, since it could synergize RF-Ⅰto recognize termination codon and release the nascent polypeptide. Recently, several hypothesises and models about the mechanism of stop codon recognition have been put forward basing on the data from in vivo and in vitro activity assay. Especially, the study on crystal structure of RF-Ⅰand the dimensional research of the two release factors complex provide the firsthand evidence about the termination of protein biosynthesis mechanism..