A cDNA has been isolated for an adult male specific gene in Drosophila that contains the repetitive element opa. We have named this gene Dromsopa for Drosophila male specific opa containing gene. The 0.6 kb mRNA for this gene is only found in the abdominal region of adult male Drosophila and in no other tissue or at other developmental stages. The Dromsopa opa repeat codes for the usual stretch of poly(glutamine) interrupted by histidine residues. The opa repetitive element was originally found in the Drosophila Notch gene (Kidd, S. et al. (1983) Cell 34, 431-433 and Wharton, K.A. (1985) Cell 40, 55-62) and has, more recently, been found in genes under developmental or tissue specific control from yeast to humans. The gene was cloned using a genomic fragment during a chromosomal walk upstream of the AP3 gene located at chromosomal location 79CD on the left arm of the third chromosome (Kelley, M.R. et al. (1989) Mol. Cell. Biol. 9, 965-973). The Dromsopa gene has no other identity with genes currently in the databases, once the opa repeat is excluded. The possibility that the Dromsopa gene is a male specific regulatory factor is under investigation as is its precise location within the abdomen, such as in germ line tissue.