Glutathione S Transferase (GST)

Glutathione S-transferases (GSTs), previously known as ligandins, comprise a family of eukaryotic and prokaryotic phase II metabolic isozymes best known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to xenobiotic substrates for the purpose of detoxification. The GST family consists of three superfamilies: the cytosolic, mitochondrial, and microsomal—also known as MAPEG—proteins.
A GST-tag is often used to separate and purify proteins that contain the GST-fusion protein. The tag is 220amino acids(roughly 26 KDa) in size,which, compared to tags such as theMyc-tagor theFLAG-tag, is quite large. It can be fused to either theN-terminusorC-terminusof a protein. However, many commercially available sources of GST-tagged plasmids include athrombindomain for cleavage of the GST tag during protein purification.