Arabidopsis wild-type Col-0 was chosen as material to analyze the amino acid sequence comparison of type one protein phosphatase (TOPP) family.The TOPP4,a member of TOPP family,was prokaryotic expression to prepare and purify polyclonal antibodies.The results indicated as follow:(1)The prokaryotic expression plasmids of pEGM-4T-3-TOPP4 and pET-28a-GFP-N150 were constructed and transformed into Escherichia coli BL21 (DE3) strain.(2)The soluble GST-TOPP4 protein of 62 kD and His-GFP-N150 protein of 34 kD were expression by IPTG induction.(3)The recombinant protein GST-TOPP4 was purified,and then used as the antigen to immune the rabbits.The prepared polyclonal antibodies serum,whose titer was over 1∶400 000,was achieved.(4)The serum was purified by CNBr-activated Sepharose,which was linked with His-GFP-N150 protein,to obtain anti-TOPP4 polyclonal antibodies with great specificity.Our studies suggested that the specific TOPP4 polyclonal antibodies have been purified.