核糖体蛋白L11(ribosome protein L11)是一种高度保守的蛋白质,是蛋白质合成过程中所必需的。L11由N-末端和C-末端两个结构域组成。L11的N-末端在蛋白质合成中作为分子开关,在多肽链的延伸阶段与延伸因子EF-G相互作用,对EF-G依赖的迁移过程是必需的;在肽链终止阶段与肽链释放因子RF1相互作用,对RF1识别终止密码子UAG的功能是必需的。L11上有一个与噻唑类(thiazole)抗生素结合的靶位点,这种结合会抑制依赖延伸因子的核糖体的活性。
Termination of translation in eukaryotes requires two polypeptide chain-release factors, eRF1 and eRF3. eRF1 recognizes stop signals, whereas eRF3 is a ribosome-dependent and eRFl-dependent GTPase. Polypeptide release factor eRF3 consists of N-terminal variable region and C-terminal conserved part. C-terminal part of eRF3 is responsible for termination of the translation, In the present study, the C-terminal of Euplotes octocarinatus eRF3 （eRF3C） and truncate eRF3C lacking 76 amino acids in C-terminal （eRF3Ct） were expressed in Escherichia coll. The recombinant GST-eRF3C and GST-eRF3Ct polypeptides were purifled by affinity chromatography using glutathione Sepharose 4B column. After enzymatic cleavage of GST tail, the eRF3C and eRF3Ct protein were obtained. Pull-down analysis showed that the recombinant GST-eRF3C and GST-eRF3Ct polypeptides interacted with E. octocarinatus polypeptide chain release factor eRF1a. This result suggested that the C-terminal of eRF3 having 76 amino acids were not required for the binding of eRFla in Euplotes octocarinatus.
