Sperizin is a murine RING zinc-finger protein specifically expressed in haploid germ cells

Through the preparation of a subtracted cDNA library, we have extensively isolated genes whose expression is induced in mouse spermatogenic cells. One of the genes encoded a protein with a RING zinc-finger motif, which we termed sperizin (spermatid-specific ring zinc finger). Transcription of the sperizin gene was not observed in prepubertal testis, but became detectable at day 23. Northern and in situ hybridization analyses indicated that the sperizin gene was exclusively expressed in the round spermatid. The sperizin gene is intronless, and GFP-tagged sperizin was found to be localized in the cytoplasm of ectopically expressed somatic cultured cells. We assigned the chromosomal localization of the sperizin gene to chromosome 17 using an interspecific backcross mapping panel. The data suggest that we have identified a new member of the RING-finger family of proteins that may be involved in spermatogenesis.