Abstract
A new gene, msta, was found in region 2E of the Drosophila melanogaster X-chromosome. The gene is expressed in the head of adults, consists of two exons, and codes for a protein containing the SET domain, as characteristic of several proteins modulating chromatin structure and gene activity. Its shortened copy, msts, was found in the vicinity of msta. Since the divergence between their coding regions was lower than between the introns, msts was assumed to have functioned for some time after duplication. The genes proved to be separated by the 1.688-2E complex microsatellite.