A novel Drosophila retina gene with MORN repeats is conserved in Humans. K.L. Mecklenburg. Biology, Indiana University South Bend, South Bend, IN.

   Molecular screens utilizing Drosophila head-specific cDNAs have identified many new genes expressed in the visual system. A cDNA first described as "9C4" hybridizes to an abundant 1.0 kb transcript expressed in heads from wild-type and the mutant sevenless (sev), but not in the heads of the mutant eyes absent (eya). Examination of the cDNA and genomic sequence indicates two introns and predicts a 198 amino acid protein. Cross-hybridization studies and sequence comparisons suggest that the 9C4 transcript is conserved. Radioactively labeled cDNA synthesized from bovine retina strongly hybridizes to 9C4. Interestingly, the predicted Drosophila protein shares similarity to a novel human protein predicted from cDNA sequence. The sequences are 50% identical, with an additional 16% conserved substitutions. The human gene is located on chromosome 10 and is represented in cDNA libraries prepared from different tissues, including retina. While the function of the putative human and Drosophila proteins is not yet clear, they encode 4 copies of a short repeat associated with a Membrane Organization and Recognition Nexus (MORN) function. The expression of the Drosophila protein and the human transcript is currently being investigated.