This gene encodes a member of the selenoprotein family, characterized by a selenocysteine (Sec) residue at the 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. Studies suggest that this protein may regulate cytokine production, and thus play a key role in the control of the inflammatory response. Alternative splicing results in multiple transcript variants encoding different isoforms.