THE INOSITOL 1,4,5-TRIPHOSPHATE RECEPTOR EXPRESSION IN DROSOPHILA SUGGESTS A ROLE FOR IP3 SIGNALING IN MUSCLE DEVELOPMENT AND ADULT CHEMOSENSORY FUNCTIONS

Inositol 1,4,5-triphosphate (IP3) is generated as a second messenger i n many diverse cellular signalling pathways. In general these signalli ng pathways activate a membrane-bound phospholipase C, which cleaves t he phospholipid phosphatidylinositol bisphosphate to generate IP3 and diacylglycerol. IP3 binds to a specific intracellular receptor, which is a membrane protein and a ligand-gated Ca2+ channel, that causes Ca2 + release from intracellular stores. The inositol 1,4,5-triphosphate r eceptor (IP(3)R) is thus an integral part of the IP3 signalling pathwa y and can be used as a marker to identify biological processes that us e IP3 as a second messenger, We have used an affinity-purified antibod y, directed against a bacterial fusion protein and containing 339 amin o acids of the Drosophila IP(3)R, to detect this protein in adult head s and during embryonic and pupal development. Our results suggest that in Drosophila the IP3 signalling pathway is used during muscle develo pment, primarily when myoblasts undergo rapid multiplication, in both embryos and pupae. In adults, IP3 is probably a second messenger in mo re than one sensory transduction pathway, as well as in other as yet u ndefined brain and muscle functions. (C) 1995 Academic Press, Inc.