Abstract: It was to express human Smad4 gene in prokaryotic cells and purify the GST-Smad4 fusion protein. The full-length Smad4 genewas amplified by PCR and cloned into prokaryotic expression vector pGEX-4T-1. The recombinant plasmid pGEX-4T-1-Smad4 was transformedinto E.coli BL21(DE3)and exogenous protein was induced by IPTG. After purification using MagneGST particles, the GST-Smad4 fusionprotein was further identified by Western blot. Results showed that the recombinant plasmid pGEX-4T-1-Smad4 was constructed successfully.When BL21(DE3)cells transformed with pGEX-4T-1-Smad4 were cultured at 30℃ and induced with 0.2 mmol/L IPTG, GST-Smad4 proteinwas obtained in a large quantity in supernatant. The purified GST-Smad4 was further identified specifically by Smad4 antibody. Therefore, itproved that GST-Smad4 fusion protein was successfully expressed and purified, and could be used for further study of the function of Smad4.

Key words: Smad4 , Prokaryotic expression , Protein purification