GST-tag (glutathione S-transferase) from a parasite Schistosoma japonicum is a tag added to a protein of interest as a fusion protein for protein purification and detection. It allows purification by affinity chromatography on immobilized glutathione. GST is utilized as a fusion protein with foreign proteins in a range of prokaryotic expression vectors, including the pGEX family of vectors. The tag is 220 amino acid long, ca. 26 kDa which makes it quite large compare to Myc or FLAG tags.
