Selenoproteins of the glutathione system

Abstract

The protein family of glutathione peroxidases (GPx) is spread over the entire living kingdom. Four distinct molecular clades characterized by an active site selenocysteine residue coexist in vertebrates. Such selenoperoxidases have sporadically been detected in lower animals, while GPx homologs having the active site selenocysteine replaced by cysteine are more common and appear to be the only representatives of the family in plants and bacteria.