Objective to prepare ea and ed protein of p - galactosidase with gst fusion protein by pgex - 4t - 2 expression system , and study its a complementation activity . to lay a good foundation for further study of cedia and utilization in expression immunoassay . methods an artificial synthesized dna segment coding for residues 6 - 56 ( modified ) of p - galactosidase ( ed protein ) was ligated to pgex - 4t - 2 vector 实验方法通过人工合成编码d半乳糖昔酶ed蛋白的dna并插入原核表达载体pgex 4t 2 ；从陀v p galactosldasecontrolvector质粒中用sal及earl进行双酶切得到编码卜半乳糖昔酶a一受体（ ea ）的大部分dna ， n端再加上约60hp人工合成洲a ，连接后转入pgex叶t亿载体中。
