Isolation of a homoeo box-containing gene from the engrailed region of Drosophila and the spatial distribution of its transcripts.

The engrailed locus of Drosophila melanogaster has the characteristics of both a homoeotic gene and a segmentation gene: like a homoeotic gene, it specifies the development of specific compartments of the Drosophila embryo (the posterior compartments of each segment), and, like mutations of segmentation genes, lethal alleles of engrailed affect also the pattern of segmentation of the embryo. Here we report that like many of the homoeotic genes of the bithorax and Antennapedia complexes, engrailed has a 'homoeo box' sequence: also, like the segmentation gene fushi tarazu, the engrailed gene displays a periodic pattern of expression in Drosophila embryos.