Use of pEX and pGEX bacterial heterologous protein expression systems for recombinant oncoprotein production and...

In order to study the role played by known and novel genes in growth control and neoplasia, we here compare the pEX and pGEX bacterial expression systems for recombinant oncoprotein production and for generation of specific antisera. The results of five pEX (MS2-c-Fos, MS2-Fra-1, MS2-JunD, bgal-c-Jun and bgal-JunB) and two pGEX [glutathione S-transferase (GSH)-JE/MCP-1 and GST-JunD] fusion-protein productions are presented. Higher (15-43-fold) yields are obtained with the pEX system, but only the pGEX system allows separation of the protein of interest from the fusion moiety by digestion with specific proteases. The degree of fusion-protein purification, as assessed by SDS/PAGE, is similar for both systems. Proteins produced by both systems were successfully used in the generation of specific antisera. The choice between the pEX and pGEX systems is dependent upon the specific recombinant protein produced.