A Human Opsin-Related Gene That Encodes a Retinaldehyde-Binding Protein

Shen, Daiwei; Jiang, Meisheng; Hao, Wenshan; Li, Tao; Salazar, Marthenn; Fong, Henry K. W.

doi:10.1021/bi00248a022

Cited by 82 publications

(71 citation statements)

References 31 publications

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“…The cytoplasmic and extracellular tails are significantly different in sequence and length. (Nathans and Hogness, 1984), blue cone opsin (Nathans et al, 1986), red and green cone opsins (Nathans et al, 1986), RGR (Shen et al, 1994), peropsin (Hui et al, 1997), and encephalopsin (Blackshaw and Snyder, 1999) ORFs. Portions of the ORFs corresponding to the transmembrane domains are shown in white and are labeled.…”

Section: Cloning Of Mouse Melanopsinmentioning

confidence: 99%

A Novel Human Opsin in the Inner Retina

et al. 2000

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Here we report the identification of a novel human opsin, melanopsin, that is expressed in cells of the mammalian inner retina. The human melanopsin gene consists of 10 exons and is mapped to chromosome 10q22. This chromosomal localization and gene structure differs significantly from that of other human opsins that typically have four to seven exons. A survey of 26 anatomical sites indicates that, in humans, melanopsin is expressed only in the eye. In situ hybridization histochemistry shows that melanopsin expression is restricted to cells within the ganglion and amacrine cell layers of the primate and murine retinas. Notably, expression is not observed in retinal photoreceptor cells, the opsin-containing cells of the outer retina that initiate vision. The unique inner retinal localization of melanopsin suggests that it is not involved in image formation but rather may mediate nonvisual photoreceptive tasks, such as the regulation of circadian rhythms and the acute suppression of pineal melatonin. The anatomical distribution of melanopsinpositive retinal cells is similar to the pattern of cells known to project from the retina to the suprachiasmatic nuclei of the hypothalamus, a primary circadian pacemaker.

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Section: Cloning Of Mouse Melanopsinmentioning

confidence: 99%

A Novel Human Opsin in the Inner Retina

et al. 2000

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“…tonated and protonated forms, respectively, of this Schiff base (16). Exposing RGR to light induces photoisomerization of the all-trans-RAL to 11-cis-RAL (15).…”

Section: Charles Kenneth Feldman and Jules And Doris Stein Research Tmentioning

confidence: 99%

Retinal Pigment Epithelium-Retinal G Protein Receptor-Opsin Mediates Light-dependent Translocation of All-trans-retinyl Esters for Synthesis of Visual Chromophore in Retinal Pigment Epithelial Cells

Radu¹,

Hu²,

Peng³

et al. 2008

Journal of Biological Chemistry

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Visual perception begins with the absorption of a photon by an opsin pigment, inducing isomerization of its 11-cis-retinaldehyde chromophore. After a brief period of activation, the resulting all-trans-retinaldehyde dissociates from the opsin apoprotein rendering it insensitive to light. Restoring light sensitivity to apo-opsin requires thermal re-isomerization of alltrans-retinaldehyde to 11-cis-retinaldehyde via an enzyme pathway called the visual cycle in retinal pigment epithelial (RPE) cells. Vertebrates can see over a 10 8 -fold range of background illumination. This implies that the visual cycle can regenerate a visual chromophore over a similarly broad range. However, nothing is known about how the visual cycle is regulated. Here we show that RPE cells, functionally or physically separated from photoreceptors, respond to light by mobilizing all-trans-retinyl esters. These retinyl esters are substrates for the retinoid isomerase and hence critical for regenerating visual chromophore. We show in knock-out mice and by RNA interference in human RPE cells that this mobilization is mediated by a protein called "RPE-retinal G protein receptor" (RGR) opsin. These data establish that RPE cells are intrinsically sensitive to light. Finally, we show that in the dark, RGR-opsin inhibits lecithin:retinol acyltransferase and all-trans-retinyl ester hydrolase in vitro and that this inhibition is released upon exposure to light. The results of this study suggest that RGR-opsin mediates light-dependent translocation of all-trans-retinyl esters from a storage pool in lipid droplets to an "isomerase pool" in membranes of the endoplasmic reticulum. This translocation permits insoluble all-trans-retinyl esters to be utilized as substrate for the synthesis of a new visual chromophore.The opsins include a group of light-sensitive G protein-coupled receptors. The ligand for most opsins is 11-cis-retinaldehyde (11-cis-RAL), 3 which is covalently coupled to a Lys residue in the opsins as a Schiff base. Absorption of a photon by most photoreceptor opsins isomerizes the 11-cis-RAL to all-transretinaldehyde (all-trans-RAL), inducing a conformational change that activates the G protein (transducin) and begins the visual transduction cascade (1). In the case of vertebrate photoreceptor opsins (rhodopsin and the cone opsins), the Schiff base is hydrolyzed and all-trans-RAL dissociates following photoisomerization. Restoration of light sensitivity to the resulting apo-opsin requires thermal re-isomerization of all-trans-RAL to 11-cis-RAL via a multistep enzyme pathway called the visual cycle in cells of the adjacent retinal pigment epithelium (RPE) (2) (Fig. 1). In contrast, all-trans-RAL remains covalently bound to many invertebrate opsins following photoisomerization. Here, the bound all-trans-RAL is re-isomerized in situ back to 11-cis-RAL by absorption of a second photon through a process called photoregeneration (3)(4)(5). Besides rhodopsin and the cone opsins, vertebrates contain several "nonvisual" opsins with sequence similarity...

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“…OPN5 appears to be a deep-brain photopigment in the hypothalamus of birds and is thought to contribute to seasonal reproduction (19)(20)(21)(22); it has been immunolocalized to the mammalian inner retina (13, 16) (SI Text); however, to date, no retinal function for this mammalian pigment has been identified. We did not examine two other pigments, retinal G protein-coupled receptor (RGR) opsin (23) and peropsin (RRH) (24). RGR opsin participates in retinoid turnover (25,26), whereas RRH is expressed principally in the retinal pigment epithelium (24), a cell layer absent in the photoentrainable ex vivo retina preparation (7).…”

mentioning

confidence: 99%

Neuropsin (OPN5)-mediated photoentrainment of local circadian oscillators in mammalian retina and cornea

Buhr

Yue

Ren

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

131

181

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The molecular circadian clocks in the mammalian retina are locally synchronized by environmental light cycles independent of the suprachiasmatic nuclei (SCN) in the brain. Unexpectedly, this entrainment does not require rods, cones, or melanopsin (OPN4), possibly suggesting the involvement of another retinal photopigment. Here, we show that the ex vivo mouse retinal rhythm is most sensitive to short-wavelength light but that this photoentrainment requires neither the short-wavelength-sensitive cone pigment [S-pigment or cone opsin (OPN1SW)] nor encephalopsin (OPN3). However, retinas lacking neuropsin (OPN5) fail to photoentrain, even though other visual functions appear largely normal. Initial evidence suggests that OPN5 is expressed in select retinal ganglion cells. Remarkably, the mouse corneal circadian rhythm is also photoentrainable ex vivo, and this photoentrainment likewise requires OPN5. Our findings reveal a light-sensing function for mammalian OPN5, until now an orphan opsin.

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A Human Opsin-Related Gene That Encodes a Retinaldehyde-Binding Protein

Cited by 82 publications

References 31 publications

A Novel Human Opsin in the Inner Retina

A Novel Human Opsin in the Inner Retina

Retinal Pigment Epithelium-Retinal G Protein Receptor-Opsin Mediates Light-dependent Translocation of All-trans-retinyl Esters for Synthesis of Visual Chromophore in Retinal Pigment Epithelial Cells

Neuropsin (OPN5)-mediated photoentrainment of local circadian oscillators in mammalian retina and cornea

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