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    Photochemistry of retinal chromophore in mouse melanopsin

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    https://www.ncbi.nlm.nih.gov/pubmed/18579788
    Permanent Link
    https://doi.org/10.1073/pnas.0711397105
    http://hdl.handle.net/11603/13470
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    • UMBC Biological Sciences Department
    • UMBC Faculty Collection
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    Author/Creator
    Walker, Marquis T.
    Brown, R. Lane
    Cronin, Thomas W.
    Robinson, Phyllis R.
    Date
    2008-06-25
    Type of Work
    5 pages
    Text
    journal articles
    Citation of Original Publication
    Marquis T. Walker, R. Lane Brown, Thomas W. Cronin, and Phyllis R. Robinson, Photochemistry of retinal chromophore in mouse melanopsin, PNAS July 1, 2008 105 (26) 8861-8865; https://doi.org/10.1073/pnas.0711397105
    Rights
    This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
    Subjects
    photochemistry
    retina
    opsin
    melanopsin
    Abstract
    In mammals, melanopsin is exclusively expressed in intrinsically photosensitive retinal ganglion cells (ipRGCs), which play an important role in circadian photoentrainment and other nonimage-forming functions. These ipRGCs reside in the inner retina, far removed from the pigment epithelium, which synthesizes the 11-cis retinal chromophore used by rod and cone photoreceptors to regenerate opsin for light detection. There has been considerable interest in the identification of the melanopsin chromophore and in understanding the process of photopigment regeneration in photoreceptors that are not in proximity to the classical visual cycle. We have devised an immuno-magnetic purification protocol that allows melanopsin-expressing retinal ganglion cells to be isolated and collected from multiple mouse retinas. Using this technique, we have demonstrated that native melanopsin in vivo exclusively binds 11-cis retinal in the dark and that illumination causes isomerization to the all-trans isoform. Furthermore, spectral analysis of the melanopsin photoproduct shows the formation of a protonated metarhodopsin with a maximum absorbance between 520 and 540 nm. These results indicate that even if melanopsin functions as a bistable photopigment with photo-regenerative activity native melanopsin must also use some other light-independent retinoid regeneration mechanism to return to the dark state, where all of the retinal is observed to be in the 11-cis form.


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    Albin O. Kuhn Library & Gallery
    University of Maryland, Baltimore County
    1000 Hilltop Circle
    Baltimore, MD 21250
    www.umbc.edu/scholarworks

    Contact information:
    Email: scholarworks-group@umbc.edu
    Phone: 410-455-3544


    If you wish to submit a copyright complaint or withdrawal request, please email mdsoar-help@umd.edu.