Characterisation of T48, a target of homeotic gene regulation in Drosophila embryogenesis.

In Drosophila, the homeotic genes encode transcription factors which specify segmental identities during embryogenesis by directly regulating subordinate target genes. A chromatin immunopurification approach has been used to identify targets of the homeotic gene Ultrabithorax (Ubx). We report here the characterisation of a candidate target gene which is positively regulated by the homeotic genes Ubx and abdominal-A in both the epidermis and the midgut visceral mesoderm and encodes a novel transmembrane protein. By mapping the cis-regulatory regions of this gene, we have identified elements responsible for mediating homeotic regulation, and show that they contain in vitro Ubx binding sites. Therefore, we suggest that this is an example of a direct target of regulation by homeotic genes in two germlayers.