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 di rect interaction between these proteins from expression studies conduc ted in cultured cells, in yeast, and in the imaginal wing disc. deltex binds specifically to the Notch ankyrin repeats, a region that is cru cial for Notch signaling and that constitutes the most conserved domai n among Notch family members. In addition, we present a new Notch alle le, N-su42c, that is associated with a missense mutation within the fi fth ankyrin repeat. In addition to representing a new class of viable Notch allele, this mutation behaves similarly to mutations of deltex a nd further implicates the ankyrin repeats in Notch function.