Thioredoxin reductases (TRs) are important redox regulatory enzymes, which control the
redox state of thioredoxins. Mammals have cytosolic and mitochondrial TRs, which contain
an essential selenocysteine residue and reduce cytosolic and mitochondrial thioredoxins. In
addition, thioredoxin/glutathione reductase (TGR) was identified, which is a fusion of an N-
terminal glutaredoxin domain and the TR module. Here we show that TGR is expressed at
low levels in various tissues but accumulates in testes after puberty. The protein is …