Interphotoreceptor Retinoid‐binding Protein and Α‐tocopherol Preserve the Isomeric and Oxidation State of Retinol

Crouch, Rosalie K.; Hazard, E. Starr; Lind, Thomas; Wiggert, Barbara; Chader, Gerald J.; Corson, D. Wesley

doi:10.1111/j.1751-1097.1992.tb02154.x

Cited by 88 publications

(67 citation statements)

References 18 publications

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“…In this connection, Crouch et al (1992) made the interesting observation that IRBP has significant activity in preserving the isomeric and oxidation state of retinol. The mechanism of this activity is not known.…”

Section: Transgenic and Knock-out Mouse Modelsmentioning

confidence: 99%

Evolution of the visual cycle: the role of retinoid-binding proteins

Gonzalez‐Fernandez¹

2002

Journal of Endocrinology

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The trafficking of retinoids in the retina represents a model to study soluble hormone-binding proteins in a complex system subject to profound evolutionary adaptations. Although a remarkable illustration of convergent evolution, all visual systems detect light in the same way, that is through the photoisomerization of an 11-cis retinoid to a corresponding trans isomer. What is strikingly different between the systems, is the mechanism by which the 11-cis chromophore is reformed and visual pigment regenerated in a process known as the visual cycle. The variations of the cycle address a problem inherent to retinoids themselves. That is, the properties that make these molecules suited for light detection also account for their susceptibility to oxidative and isomeric degradation, and cellular toxicity. The cycle therefore provides an opportunity to examine the role of soluble hormonebinding proteins within an integrative and evolutionary context. The present review focuses on interphotoreceptor retinoid-binding protein (IRBP), a controversial glycolipoprotein that recruits a protein fold common to Cterminal-processing proteases and the crotonase family. This unorthodox retinoid-binding protein is entrapped in the subretinal compartment of those eyes that translocate visual cycle retinoids between the photoreceptors and the retinal pigment epithelium. Recent studies suggest that we should look beyond a strictly carrier function if we are to appreciate the role of IRBP in the visual cycle. Here we draw lessons from other soluble hormone-binding proteins to anticipate avenues of future research likely to provide insight into the structure and function of IRBP in vision.

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Section: Transgenic and Knock-out Mouse Modelsmentioning

confidence: 99%

Evolution of the visual cycle: the role of retinoid-binding proteins

Gonzalez‐Fernandez¹

2002

Journal of Endocrinology

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“…11-cis retinal, again transported by IRBP, crosses the sub-retinal space and re-enters the photoreceptors (Ala-Laurila et al, Crouch et al, 1992;Wu et al, 2007). Once inside the outer segment it is transported back into the disc membrane, and the newly generated 11-cis retinal can re-bind opsin -a functional visual pigment has been regenerated.…”

Section: Figure 9 Images From a Patient With Fundus Albipunctatus (Rmentioning

confidence: 99%

Differentiating drusen: Drusen and drusen-like appearances associated with ageing, age-related macular degeneration, inherited eye disease and other pathological processes

Khan

Mahroo

Khan

et al. 2016

Progress in Retinal and Eye Research

172

159

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Drusen are discussed frequently in the context of their association with age-related macular degeneration (AMD). Some types may, however, be regarded as a normal consequence of ageing; others may be observed in young age groups. They also occur in a number of inherited disorders and some systemic conditions. Whilst drusen are classically located external (sclerad) to the retinal pigment epithelium, accumulations of material internal (vitread to) this layer can display a drusen-like appearance, having been variously termed pseudodrusen or subretinal drusenoid deposits. This review first briefly presents an overview of drusen biogenesis and subclinical deposit. The (frequently overlapping) subtypes of clinically detectable deposit, seen usually in the context of ageing or AMD, are then described in more detail, together with appearance on imaging modalities: these include hard and soft drusen, cuticular drusen, reticular pseudodrusen and "ghost drusen". Eye disorders other than AMD which may exhibit drusen or drusen-like features are subsequently discussed: these include monogenic conditions as well as conditions with undefined inheritance, the latter including some types of early onset drusen such as large colloid drusen. A number of systemic conditions in which drusen-like deposits may be seen are also considered. Throughout this review, high resolution images are presented for most of the conditions discussed, particularly the rarer ones, providing a useful reference library for images of the range of conditions associated with drusen-like appearances. In the final section, some common themes are highlighted, as well as a brief discussion of some future avenues for research.

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“…IRBP, which is a 140-kDa glycoprotein and is the major soluble protein component of the IPM, is known to bind various isomeric and chemical forms of retinoids as well as long chain fatty acids (3,4). Participation of this protein in shuttling of retinoids in the IPM has been implied by the observations that its retinoid content is modulated by light (5) and that binding of retinoids to IRBP stabilizes them against degradation (6,7). It was also reported that IRBP can take up 11-cis-retinal from RPE (8 -10) and that it can efficiently deliver 11-cis-retinal to bleached ROS (11,12).…”

mentioning

confidence: 98%

Docosahexaenoic Acid Modulates the Interactions of the Interphotoreceptor Retinoid-binding Protein with 11-cis-Retinal

Chen

Houghton

Brenna

et al. 1996

Journal of Biological Chemistry

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Rapid transport of retinoids across the interphotoreceptor matrix is a critical part of the visual cycle, since it serves to replenish bleached rhodopsin with its chromophore 11-cis-retinal. The transport of retinoids in the interphotoreceptor matrix is believed to be mediated by the interphotoreceptor retinoid-binding protein (IRBP), a protein that, in addition to possessing two retinoidbinding sites, associates in vivo with long chain fatty acids. Here, the interrelationships between binding of the two types of ligands to IRBP were studied. The composition of fatty acids associated with IRBP in bovine retina was determined, and it was found that polyunsaturated fatty acids constitute a significant fraction of those. It was further found that docosahexaenoic acid, but not palmitic acid, induced a rapid and specific release of 11-cis-retinal from one of the protein's retinoidbinding sites. Based on these results and on the additional observation that a steep concentration gradient of docosahexaenoic acid exists between photoreceptor and pigment epithelium cells, a model for the mechanism by which IRBP may target 11-cis-retinal to photoreceptor cells is proposed.Vitamin A is essential for vision, since one of its metabolites, 11-cis-retinal, serves as the chromophore for the visual protein rhodopsin. Vitamin A circulates in blood and enters the eye in the form of all-trans-retinol. This form is taken up from the circulation by retinal pigment epithelium (RPE) 1 cells, which contain the enzymatic machinery necessary for conversion of all-trans-retinol to 11-cis-retinal. The later retinoid is transported to photoreceptor outer segments (ROS), where it associates with opsin to form rhodopsin. Exposure to light leads to isomerization of rhodopsin-bound 11-cis-retinal to the all-trans form, which is then hydrolyzed from the protein and reduced to all-trans-retinol. All-trans-retinol is transferred back to the RPE for reisomerization and oxidation (for review see Ref. 1). Thus, continuous shuttling of retinoids between photoreceptor and pigment epithelium cells across the aqueous compartment that separates them, the interphotoreceptor matrix (IPM), is a critical part of the visual cycle.The hydrophobic nature of retinoids and their lability when dissolved in water raise the question of how their rapid transport across an aqueous compartment is accomplished. The details of this process are not clear at present, but it is generally believed to be mediated by a protein in the IPM, the interphotoreceptor retinoid-binding protein (IRBP) (see Ref. 2 for review). IRBP, which is a 140-kDa glycoprotein and is the major soluble protein component of the IPM, is known to bind various isomeric and chemical forms of retinoids as well as long chain fatty acids (3, 4). Participation of this protein in shuttling of retinoids in the IPM has been implied by the observations that its retinoid content is modulated by light (5) and that binding of retinoids to IRBP stabilizes them against degradation (6, 7). It was also reported that IRBP c...

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Interphotoreceptor Retinoid‐binding Protein and Α‐tocopherol Preserve the Isomeric and Oxidation State of Retinol

Cited by 88 publications

References 18 publications

Evolution of the visual cycle: the role of retinoid-binding proteins

Evolution of the visual cycle: the role of retinoid-binding proteins

Differentiating drusen: Drusen and drusen-like appearances associated with ageing, age-related macular degeneration, inherited eye disease and other pathological processes

Docosahexaenoic Acid Modulates the Interactions of the Interphotoreceptor Retinoid-binding Protein with 11-cis-Retinal

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