DMRT1 is found in a cluster with two other members of the gene family, having in common a zinc finger-like DNA-binding motif (DM domain). The DM domain is an ancient, conserved component of the vertebrate sex-determining pathway that is also a key regulator of male development in flies and nematodes, and is found to be the key sex-determining factor in chickens. This gene exhibits a gonad-specific and sexually dimorphic expression pattern, just like the related doublesex gene in fruit flies. The protein contains a nuclear localization signal between the 2 zinc-binding sites of the DM domain, which is located in the N terminus. Immunohistochemical analysis of adult human testis revealed that DMRT1 localized to nuclei of Sertoli cells, spermatogonia, and spermatocytes.