title: Spontaneous activation of visual pigments in relation to openness/closedness of chromophore-binding pocket.
abstract: Visual pigments can be spontaneously activated by internal thermal energy, generating noise that interferes with real-light detection. Recently, we developed a physicochemical theory that successfully predicts the rate of spontaneous activity of representative rod and cone pigments from their peak-absorption wavelength (λmax), with pigments having longer λmaxbeing noisier. Interestingly, cone pigments may generally be ~25 fold noisier than rod pigments of the same λmax, possibly ascribed to an 'open' chromophore-binding pocket in cone pigments defined by the capability of chromophore-exchange in darkness. Here, we show in mice that the λmax-dependence of pigment noise could be extended even to a mutant pigment, E122Q-rhodopsin. Moreover, although E122Q-rhodopsin shows some cone-pigment-like characteristics, its noise remained quantitatively predictable by the 'non-open' nature of its chromophore-binding pocket as in wild-type rhodopsin. The openness/closedness of the chromophore-binding pocket is potentially a useful indicator of whether a pigment is intended for detecting dim or bright light.
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.|Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States.|Biochemistry, Cellular and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, United States.
authors.forename: Wendy Wing Sze
authors.initials: WW
authors.lastname: Yue
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, Boston, United States.
authors.forename: Rikard
authors.initials: R
authors.lastname: Frederiksen
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.|Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States.
authors.forename: Xiaozhi
authors.initials: X
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Membrane Biology, Peking University, Beijing, China.|McGovern Institute for Brain Research, Peking University, Beijing, China.|Center for Quantitative Biology, Peking University, Beijing, China.|Peking-Tsinghua Center for Life Sciences, Beijing, China.|College of Life Sciences, Peking University, Beijing, China.
authors.forename: Dong-Gen
authors.initials: DG
authors.lastname: Luo
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Shichida
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, Boston, United States.
authors.forename: M Carter
authors.initials: MC
authors.lastname: Cornwall
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.|Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States.|Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, United States.
authors.forename: King-Wai
authors.identifier: 0000-0001-8880-3091
authors.initials: KW
authors.lastname: Yau
mesh_terms: D000818:Animals; D001665:Binding Sites; D055598:Chemical Phenomena; D051379:Mice; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D012168:Retinal Pigments / Q000737:chemistry* / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*
chemical_list: D012168:Retinal Pigments
keywords: mouse; neuroscience; retinal photoreceptors; spontaneous excitation; vision; visual pigment