Figure 1

Expression and purification of fusion proteins. (A) Schematic presentation of fusion proteins. TGFαL3 was fused to the N -terminal or the C-terminal of SEAD_227A with 8 an eight-amino acids linker. The linker sequence (GGSGSGGG) was indicated by a dotted rectangle. All fusion proteins were tagged with a six histidinesix-histidine tag at the C-terminal; TGFαL3, the third loop of TGFα; SEA_D227A, site mutated SEA (D227A). (B) Expression and purification of fusion proteins. E. coli BL21 (DE3) cells were transformed with plasmids encoding fusion proteins, and then induced with 0.5 mM IPTG at 22°C overnight. The proteins were separated by a 15% SDS-PAGE gel and stained with Coomassie blue. Lane 1, total cell proteins (TCP) of BL21 (DE3) with pET-22b (+); lane 2, TCP of BL21 (DE3) with pET-22b-TGFαL3SEA_D227A; lane 3, TCP of BL21 (DE3) with pET-22b-SEA_D227ATGFαL3; lane 4, purified TGFαL3SEA_D227A; lane 5, purified SEA_D227ATGFαL3.