为研究游仆虫中含有三核苷酸重复序列的GARP基因编码的GARP蛋白在细胞中的功能,利用定点突变技术,将GARP基因中的TGA突变为通用半胱氨酸密码子TGT。突变后的GARP基因构建于原核表达载体pRSETc中,得到重组质粒pRSETc-GARP,将pRSETc-GARP质粒转化至大肠杆菌BL21(DE3)中,经IPTG诱导,带有纯化标签的重组蛋白His6-GARP获得可溶表达,表达产物与抗His抗体在约26 kDa处有很强的交叉反应。His6-GARP蛋白在不同pH条件下通过两次阴离子交换层析和一次凝胶层析三步纯化达到电泳纯。
A glutamic acid-rich protein (GARP) from Euplotes octocarinatus was expressed in E. Coli in this study. The inframe TGA was successfully mutated to TGT encoding for Cysteine by site directed mutagenesis method. Recombinant ex- pression plasmid pRSETc-GARP was constructed. His6-GARP fusion protein was highly expressed "in E. coli B121 (DE3) by IPTG induction. The Western blotting with anti-His antibodies assay confirmed that the putative fusion protein with molecular mass of 26 kDa was the His6-GARP dimer. The protein was purified by ion exchange chromatography and exclusion chromatography.