ebi regulates epidermal growth factor receptor signaling pathways in Drosophila

ebi regulates the epidermal growth factor receptor (EGFR) signaling pathway at multiple steps in Drosophila development. Mutations in ebi and Egfr lea d to similar phenotypes and show genetic interactions. However, ebi does no t show genetic interactions with other RTKs (e.g., torso) or with component s of the canonical Ras/MAP kinase pathway, ebi encodes an evolutionarily co nserved protein with a unique amino terminus, distantly related to F-box se quences, and six tandemly arranged carboxy-terminal WD40 repeats. The exist ence of closely related proteins in yeast, plants, and humans suggests that ebi functions in a highly conserved biochemical pathway. Proteins with rel ated structures regulate protein degradation. Similarly, in the developing eye, ebi promotes EGFR-dependent down-regulation of Tramtrack88, an antagon ist of neuronal development.