Partner specificity is essential for proper function of the SIX-type homeodomain proteins Sine oculis and Optix during fly eye development

Dev Biol. 2005 Oct 1;286(1):158-68. doi: 10.1016/j.ydbio.2005.07.017.


The development of the Drosophila visual system utilizes two members of the highly conserved Six-Homeobox family of transcription factor, Sine oculis and Optix. Although in vitro studies have detected differences in DNA-binding and interactions with some co-factors, questions remain as to what extent the activity for these two transcriptional regulators is redundant or specific in vivo. In this work, we show that the SoD mutation within the Six domain does not abolish DNA-protein interactions, but alters co-factor binding specificity to resemble that of Optix. A mutation in the same region of Optix alters its activity in vivo. We propose that the dominant mutant phenotype is primarily due to an alteration in binding properties of the Sine oculis protein and that distinct partner interactions is one important mechanism in determining significant functional differences between these highly conserved factors during eye development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Animals, Genetically Modified
  • Conserved Sequence
  • DNA / genetics
  • DNA / metabolism
  • Drosophila / genetics
  • Drosophila / growth & development*
  • Drosophila / physiology*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / physiology*
  • Eye / growth & development*
  • Eye Proteins / genetics
  • Eye Proteins / physiology*
  • Gene Expression Regulation, Developmental
  • Genes, Dominant
  • Genes, Homeobox
  • Genes, Insect
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / physiology*
  • Molecular Sequence Data
  • Phenotype
  • Point Mutation
  • Protein Binding
  • Transcription Factors / genetics
  • Transcription Factors / physiology*


  • Drosophila Proteins
  • Eye Proteins
  • Homeodomain Proteins
  • Optix protein, Drosophila
  • So protein, Drosophila
  • Transcription Factors
  • DNA