Methionine sulfoxide reductase B3（MSRB3) is a member of the methionine sulfoxide reductases（MSR) family proteins. MSRB3 catalyzes the reduction of methionine sulfoxide to methionine. The MSRB3 enzyme acts as a monomer and requires zinc as a cofactor. MSRs are thought to defend against reactive oxygen species-induced oxidative damage in various organs， including the most environmentally exposed organ， the human skin. MSRB3 has a vital role in cold tolerance by eliminating MetO and ROS which accumulate at the ER during cold acclimation.
