title: Massive light-driven translocation of transducin between the two major compartments of rod cells: a novel mechanism of light adaptation.
abstract: We report a new cellular mechanism of rod photoreceptor adaptation in vivo, which is triggered by daylight levels of illumination. The mechanism involves a massive light-dependent translocation of the photoreceptor-specific G protein, transducin, between the functional compartments of rods. To characterize the mechanism, we developed a novel technique that combines serial tangential cryodissection of the rat retina with Western blot analysis of protein distribution in the sections. Up to 90% of transducin translocates from rod outer segments to other cellular compartments on the time scale of tens of minutes. The reduction in the transducin content of the rod outer segments is accompanied by a corresponding reduction in the amplification of the rod photoresponse, allowing rods to operate in illumination up to 10-fold higher than would otherwise be possible.
authors.affiliation: Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Maxim
authors.initials: M
authors.lastname: Sokolov
authors.forename: Arkady L
authors.initials: AL
authors.lastname: Lyubarsky
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Strissel
authors.forename: Andrey B
authors.initials: AB
authors.lastname: Savchenko
authors.forename: Viktor I
authors.initials: VI
authors.lastname: Govardovskii
authors.forename: Edward N
authors.initials: EN
authors.lastname: Pugh
authors.forename: Vadim Y
authors.initials: VY
authors.lastname: Arshavsky
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D002451:Cell Compartmentation / Q000502:physiology*; D003623:Dark Adaptation / Q000502:physiology; D005260:Female; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism; D015293:Transducin / Q000378:metabolism*
chemical_list: D015293:Transducin