Identification of the binding sites for potential regulatory proteins in the upstream enhancer element of the Drosophila fushi tarazu gene.

With a view to identifying proteins that regulate the expression of the Drosophila ftz gene we have sequenced its enhancer-like upstream element (USE) and determined the binding sites for embryonic nuclear proteins within this region by in vitro DNAaseI footprinting. We find that greater than 50% of this element is bound by nuclear protein. By footprinting and gel-retardation studies in embryonic extracts from different developmental stages, we have characterised a number of USE/protein complexes whose nature alters in concert with changes in the ftz expression pattern, suggesting that these USE-binding proteins may be involved in the regulation of gene activity. In some cases this suggestion is substantiated by the observation that the protected DNA sequences show homology to the binding sites for ftz regulating DNA-binding proteins such as the pair-rule gene product even-skipped.