This gene encodes a member of the family of pyridine nucleotide oxidoreductases. This protein catalyzes the reduction of thioredoxin, and is implicated in the defense against oxidative stress. It contains a selenocysteine (Sec) residue (which is essential for catalytic activity), encoded by a UGA codon, at the penultimate C-terminal position. The 3' UTR of Sec-containing genes have a common stem-loop structure, the sec insertion sequence (SECIS), which is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2010].