FIG. 5.

Reduction of oxidized proteins by glutaredoxin/glutathione (GRX/GSH). Through a mechanism similar to that used by TRX, GRX also forms a mixed-disulfide intermediate with an oxidized protein. This disulfide is resolved through involvement of a second Cys residue of the CXXC motif in GRX, resulting in reduction of the protein and formation of a disulfide bond in GRX. GSH directly reduces GRX again through a disulfide-exchange mechanism and is itself reduced by glutathione reductase. [Adapted from Lillig et al. (121).]