Glutathione peroxidase (GPX)/glutathione reductase is part of the hydrogen peroxide scavenging system found within the epididymis in the mammalian male reproductive tract. GPX5 expression is epididymis-specific and the transcript is unique from other GPXs because it contains a deletion resulting in an mRNA that does not contain a selenocysteine (UGA) codon (an unusual amino acid present in other GPXs). This deletion also renders the mRNA incapable of encoding an active GPX isoenzyme. For this reason, GPX5 is selenium-independent and has very little activity towards hydrogen peroxide or organic hydroperoxides. GPX5, which is bound to the acrosome of sperm, may act to protect sperm from premature acrosome reaction in the epididymis. [provided by RefSeq]
