title: The Drosophila dgq gene encodes a G alpha protein that mediates phototransduction.
abstract: We examined the roles of the Drosophila Gq alpha proteins (DGq) in the phototransduction pathway. The DGq proteins immunolocalized to the ocelli and all eight retinular photoreceptor cell rhabdomeres. An affinity-purified anti-DGq alpha immunoglobulin blocked the light-dependent GTP hydrolysis activity associated with Drosophila head membranes in vitro, suggesting that rhodopsin stimulated DGq. Dominantly active DGq1 mutants exhibited a light-independent GTPase activity and abnormal electrophysiological light responses, such as reduced retinal sensitivity and slow response kinetics compared with wild-type flies. Dominant DGq2 mutants exhibited a light-independent GTPase activity with normal electrophysiological light responses. Retinas of double mutants of DGq1, but not DGq2, with the light-dependent retinal degeneration mutant rdgB degenerated even in the dark. DGq1 stimulation of rdgB retinal degeneration in the dark was norpA-dependent. These results indicate that DGq1 mediates the stimulation by light-activated rhodopsin of the norpA-encoded phospholipase C in the visual transduction cascade.
authors.affiliation: Department of Biological Sciences, University of Notre Dame, Indiana 46556.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Shah
authors.forename: E
authors.initials: E
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Zars
authors.forename: P M
authors.initials: PM
authors.lastname: O'Day
authors.forename: D R
authors.initials: DR
authors.lastname: Hyde
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D004594:Electrophysiology; D020558:GTP Phosphohydrolases / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000502:physiology*; D005799:Genes, Dominant; D017344:Genes, Insect; D007158:Immunologic Techniques; D008027:Light; D008969:Molecular Sequence Data; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054799:Phospholipase C beta; D010727:Phosphoric Diester Hydrolases / Q000502:physiology; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D012160:Retina / Q000502:physiology; D012162:Retinal Degeneration / Q000503:physiopathology; D010738:Type C Phospholipases; D014785:Vision, Ocular / Q000502:physiology*
chemical_list: D017931:DNA Primers; D029721:Drosophila Proteins; D010727:Phosphoric Diester Hydrolases; D010738:Type C Phospholipases; C468371:NorpA protein, Drosophila; D054799:Phospholipase C beta; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase