This gene encodes a selenoprotein, which contains a selenocysteine (Sec) residue at its active site. The selenocysteine is encoded by the UGA codon that normally signals translation termination. The 3' UTR of selenoprotein genes have a common stem-loop structure, the sec insertion sequence (SECIS), that is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. This protein belongs to the methionine sulfoxide reductase (Msr) protein family which includes repair enzymes that reduce oxidized methionine residues in proteins. The protein encoded by this gene is expressed in a variety of adult and fetal tissues and localizes to the cell nucleus and cytosol.