THE DROSOPHILA ROLLED LOCUS ENCODES A MAP KINASE REQUIRED IN THE SEVENLESS SIGNAL-TRANSDUCTION PATHWAY

Mitogen-activated protein (MAP) kinases have been proposed to play a c riticalrole in receptor tyrosine kinase (RTK)-mediated signal transduc tion pathways.Although genetic and biochemical studies of RTK pathways in Caenorhabditis elegans, Drosophila melanogaster and mammals have r evealed remarkable similarities, a genetic requirement for MAP kinases in RTK signaling has not been established. During retinal development in Drosophila, the sevenless (Sev) RTK is required for development of the R7 photoreceptor cell. Components of the signal transduction path way activated by Sev in the R7 precursor include proteins encoded by t he gap1, drk, Sos, ras1 and raf loci. in this report we present eviden ce that a Drosophila MAP kinase, ERK-A, is encoded by the rolled locus and isrequired downstream of raf in the Sev signal transduction pathw ay.