Glutaredoxin(GRX), also known as thioltransferase, is member of the thiol-disulfide oxidoreductase family. Glutraredoxin catalyzes the reversible reduction of protein-glutathionyl mixed disulfides to free sulfhydryl groups though a monothiol mechanism. Mammalian Glutaredoxin is known to have two isoforms, GRX1 and GRX2. GRX1 is a cytosolic protein, whereas GRX2 is localized both in the mitochondria and nucleus.