The 26kD GST (glutathione S-Transferase) domain, encoded by the parasite Schistosoma japonicum, is easily purified by affinity chromatography on immobilized glutathione. For this reason, numerous prokaryotic expression vectors have been developed allowing research to fuse recombinant protein purification. GST is utilized as a fusion protein in protein expression from a range of prokaryotic expression vectors, including the pGEX family of vectors. Antibodies against GST will detect the expressed GST protein or a GST-fusion protein, and can be utilized for immuno-purification of GST-fusion proteins.