[Cloning of the cDNA of human PD-L1 gene and the expression of its extracellular domain in Escherichia coli].

AIM: To clone human PD-L1 cDNA and construct a prokaryotic expression vector for the extracellular domain of PD-L1 gene. METHODS: The human PD-L1 cDNA was cloned by RT-PCR from the total RNA of activated human peripheral lymphocytes. The prokaryotic expression vector for the extracellular domain of PD-L1 gene was constructed and protein expression in E.coli strain BL21(DE3) was determined. RESULTS: The full-length gene coding sequence of PD-L1 was cloned and confirmed by DNA sequencing. The prokaryotic expression vector for the extracellular domain of PD-L1 gene fused with His(6) tag at the C-terminus was then constructed. The recombinant protein was expressed in E.coli after IPTG induction and identified by Western blot. The expressed product had a relative molecular mass (M(r)) being 22 000, which was consistent with theoretical value. CONCLUSION: The PD-L1 gene was successfully cloned and the extracellular domain of the protein was expressed in E.coli, which lays the foundation for further study of the function of PD-L1.