Abstract
The somatic sexual phenotype of Drosophila is regulated by the sexual differentiation pathway. Male (DSXM) and female (DSXF) proteins encoded by doublesex (dsx), a gene at the end of this pathway, bind to three sites within a 127-bp enhancer that directs sex- and tissue-specific transcription of Yolk protein genes. We describe mutagenesis of these binding sites and the resulting effects on DSXM and DSXF binding in vitro and on gene regulation in wild-type and dsx mutant flies. The results demonstrate that DSXM represses and DSXF activates transcription from the two strongest binding sites. Thus, the pathway regulates sex-specific transcription through the male and female dsx proteins that act directly on the target gene, but with opposite effects.
