title: Multiple phosphorylation of rhodopsin and the in vivo chemistry underlying rod photoreceptor dark adaptation.
abstract: Dark adaptation requires timely deactivation of phototransduction and efficient regeneration of visual pigment. No previous study has directly compared the kinetics of dark adaptation with rates of the various chemical reactions that influence it. To accomplish this, we developed a novel rapid-quench/mass spectrometry-based method to establish the initial kinetics and site specificity of light-stimulated rhodopsin phosphorylation in mouse retinas. We also measured phosphorylation and dephosphorylation, regeneration of rhodopsin, and reduction of all-trans retinal all under identical in vivo conditions. Dark adaptation was monitored by electroretinography. We found that rhodopsin is multiply phosphorylated and then dephosphorylated in an ordered fashion following exposure to light. Initially during dark adaptation, transduction activity wanes as multiple phosphates accumulate. Thereafter, full recovery of photosensitivity coincides with regeneration and dephosphorylation of rhodopsin.
authors.affiliation: Department of Biochemistry, Box 357350, University of Washington, 98195, Seattle, WA, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kennedy
authors.forename: K A
authors.initials: KA
authors.lastname: Lee
authors.forename: G A
authors.initials: GA
authors.lastname: Niemi
authors.forename: K B
authors.initials: KB
authors.lastname: Craven
authors.forename: G G
authors.initials: GG
authors.lastname: Garwin
authors.forename: J C
authors.initials: JC
authors.lastname: Saari
authors.forename: J B
authors.initials: JB
authors.lastname: Hurley
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003624:Darkness; D004596:Electroretinography; D007700:Kinetics; D008027:Light; D013058:Mass Spectrometry; D051379:Mice; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010766:Phosphorylation; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D012172:Retinaldehyde / Q000378:metabolism; D012176:Retinoids / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism*; D012694:Serine; D013997:Time Factors; D014785:Vision, Ocular / Q000502:physiology
chemical_list: D012176:Retinoids; D012694:Serine; D012243:Rhodopsin; D012172:Retinaldehyde