Molecular analysis of Drosophila eyes absent mutants reveals features of the conserved Eya domain

The eye absent (eya) gene is critical to eye formation in Drosophila; upon loss of ega function, eye progenitor cells die by programmed cell death. Mo reover, ectopic eya expression directs eye formation, and eya functionally synergizes in vivo and physically interacts in vitro with two other genes o f eye development, sine oculis and dachshund. The Eya protein sequence, whi le highly conserved to vertebrates, is novel. To define amino acids critica l to the function of the Eya protein, we have sequenced eya alleles. These mutations have revealed that loss of the entire Eya Domain is null for eya activity, but that alleles with truncations within the Eya Domain display p artial function. We then extended the molecular genetic analysis to interac tions within the Eya Domain. This analysis has revealed regions of special importance to interaction with Sine Oculis or Dachshund. Select eya missens e mutations within the Eya Domain diminished the interactions with Sine Ocu lis or Dachshund. Taken together, these data suggest that the conserved Eya Domain is critical for eya activity and may have functional subregions wit hin it.