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. Glutaredoxin-3 (Grx3/PICOT) is an essential protein involved in the regulation of signal transduction, for instance during immune cell activation and development of cardiac hypertrophy, presumably in response to redox signals.