pALEX, a dual-tag prokaryotic expression vector for the purification of full-length proteins.

pALEX, a prokaryotic expression vector, was constructed in which the multiple cloning site (MCS, polylinker) is flanked by sequences encoding glutathione S-transferase (GST) at the 5' end and a His6 residue tag at the 3' end. Open reading frames cloned into this vector can direct production of fusion proteins with GST at their N terminus and a His6 tag at their C terminus. This allows for the purification of full-size fusion proteins by a sequential two-step procedure on glutathione-agarose and Ni(2+)-agarose columns.