The glutathione S-transferase (GST, previously known as ligandins) family of enzymes are composed of many cytosolic, mitochondrial, and microsomal proteins. GSTs are present in eukaryotes and in prokaryotes, where they catalyze a variety of reactions and accept endogenous and xenobiotic substrates.GST tag can be helpful in detecting the fusion protein during purification as well as the cleavage of GST from the protein of interest. GST tag has wide applications that could include your research on GST proteins or GST fusion recombinant proteins.