THE DROSOPHILA G-PROTEIN-COUPLED RECEPTOR KINASE HOMOLOG GPRK2 IS REQUIRED FOR EGG MORPHOGENESIS

G protein signaling is a widely utilized form of extracellular communi cation that is mediated by a family of serpentine receptors containing seven transmembrane domains, In sensory neurons, cardiac muscle and o ther tissues, G protein-coupled receptors are desensitized through pho sphorylation by a family of kinases, the G protein-coupled receptor ki nases (GRKs). Desensitization allows a cell to decrease its response t o a given signal, in the continued presence of that signal, We have id entified a Drosophila mutant, gprk2(6936) that disrupts expression of a putative member of the GRK family, the G protein-coupled receptor ki nase 2 gene (Gprk2), This mutation affects Gprk2 gene expression in th e ovaries and renders mutant females sterile. The mutant eggs contain defects in several anterior eggshell structures that are produced by s pecific subsets of migratory follicle cells, In addition, rare eggs th at become fertilized display gross defects in embryogenesis, These obs ervations suggest that developmental signals transduced by G protein-c oupled receptors are regulated by receptor phosphorylation. Based on t he known functions of G protein-coupled receptor kinases, we speculate that receptor desensitization assists cells that are migrating or und ergoing shape changes to respond rapidly to changing external signals.