Embryonic Pattern in Drosophila: The Spatial Distribution and Sequence-specific DNA Binding of engrailed Protein

The engrailed gene (en) is a regulator of pattern formation in Drosophila melanogaster. Here, we summarize immunofluorescence studies that reveal an elaborate spatial and temporal program of expression of the en gene product in the early embryo. These results suggest that en expression is controlled by a number of other genes. Likely candidates for these genes are other known pattern-forming loci. We propose that a large proportion of the extensive en locus (70 kb) contains target sequences for such controlling gene products. We also present results which demonstrate that en encodes a sequence-specific DNA-binding activity. This observation suggests that en may control selection of developmental pathways by acting as a specific regulator of transcription.