title: Light stimulates a transducin-independent increase of cytoplasmic Ca2+ and suppression of current in cones from the zebrafish mutant nof.
abstract: Transducins couple visual pigments to cGMP hydrolysis, the only recognized phototransduction pathway in vertebrate photoreceptors. Here we describe a zebrafish mutant, no optokinetic response f(w21) (nof), with a nonsense mutation in the gene encoding the alpha subunit of cone transducin. Retinal morphology and levels of phototransduction enzymes are normal in nof retinas, but cone transducin is undetectable. Dark current in nof cones is also normal, but it is insensitive to moderate intensity light. The nof cones do respond, however, to bright light. These responses are produced by a light-stimulated, but transducin-independent, release of Ca2+ into the cone cytoplasm. Thus, in addition to stimulating transducin, light also independently induces release of Ca2+ into the photoreceptor cytoplasm.
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA. sbrocker@u.washington.edu
authors.forename: Susan E
authors.initials: SE
authors.lastname: Brockerhoff
authors.forename: Fred
authors.initials: F
authors.lastname: Rieke
authors.forename: Hugh R
authors.initials: HR
authors.lastname: Matthews
authors.forename: Michael R
authors.initials: MR
authors.lastname: Taylor
authors.forename: Breandan
authors.initials: B
authors.lastname: Kennedy
authors.forename: Irina
authors.initials: I
authors.lastname: Ankoudinova
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Niemi
authors.forename: Chandra L
authors.initials: CL
authors.lastname: Tucker
authors.forename: Ming
authors.initials: M
authors.lastname: Xiao
authors.forename: Marianne C
authors.initials: MC
authors.lastname: Cilluffo
authors.forename: Gordon L
authors.initials: GL
authors.lastname: Fain
authors.forename: James B
authors.initials: JB
authors.lastname: Hurley
mesh_terms: D000221:Adaptation, Ocular / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006720:Homozygote; D017403:In Situ Hybridization; D007814:Larva; D008027:Light; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009928:Organ Specificity; D020161:Physical Chromosome Mapping; D017354:Point Mutation; D012333:RNA, Messenger / Q000096:biosynthesis; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D015398:Signal Transduction / Q000502:physiology; D015293:Transducin / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014785:Vision, Ocular / Q000235:genetics / Q000502:physiology; D015027:Zebrafish
chemical_list: D012333:RNA, Messenger; D019204:GTP-Binding Proteins; D015293:Transducin; D006152:Cyclic GMP; D002118:Calcium