Bacterial Glutathione S-transferase (GST) from Schistosoma japonicum is a widely used protein fusion partner, since it provides exhibits little effect on the biological function of the protein of interest. The GST-tag fusion protein expression system allows for efficient coupling to glutathione (GSH) agarose affinity resins and purification by a single step chromatography. This specific antibody for GST-tag fusion protein is useful for monitoring of the fusion protein expression and affinity purification. It does not recognize mammalian GST.