Cytosolic Interaction Between Deltex and Notch Ankyrin Repeats Implicates Deltex in the Notch Signaling Pathway

Genetic data from Drosophila have suggested a functional relationship between the novel cytoplasmic protein encoded by the deltex locus and the transmembrane receptor encoded by Notch. We have demonstrated a direct interaction between these proteins from expression studies conducted in cultured cells, in yeast, and in the imaginal wing disc. deltex binds specifically to the Notch ankyrin repeats, a region that is crucial for Notch signaling and that constitutes the most conserved domain among Notch family members. In addition, we present a new Notch allele, Nsu42c, that is associated with a missense mutation within the fifth ankyrin repeat. In addition to representing a new class of viable Notch allele, this mutation behaves similarly to mutations of deltex and further implicates the ankyrin repeats in Notch function.