Identification of antigens by monoclonal antibody PD4 and its expression in Escherichia coli.

Aim: To clone and express the antigen of monoclonal antibody (MAb) PD4 for further investigation of its function.

Methods: MGC803 cDNA expression library was constructed and screened with PD4 as probes to clone the antigen. After failed in the library screening, immunoprecipitation and SDS-polyacrylamide gel electrophoresis were applied to purify the antigen for sequence analysis.