Iroquois transcription factors regulate diverse aspects of developmental patterning in all metazoans. Despite their widespread importance, the direct targets of the Iroquois are poorly understood. Here, we use in vitro site selection to define the DNA-binding preference of the Drosophila Iroquois Mirror. We use electrophoretic mobility shift assays to determine the critical nucleotides for Mirror binding and to show that this site is recognized by other Drosophila Iroquois transcription factors. This site also is recognized by vertebrate Iroquois transcription factors. Transgenic analysis demonstrates that Drosophila Iroquois proteins recognize this site in vivo to mediate transcriptional repression. We further show that Iroquois transcription factors form homodimers and heterodimers, suggesting that combinatorial binding may contribute to gene regulation by this family.

Original languageEnglish
Pages (from-to)14671-14676
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number41
StatePublished - Oct 11 2005


  • Development
  • Drosophila
  • Fringe
  • Notch
  • Planar polarity


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