rhodopsin

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rhodopsin

 [ro-dop´sin]
visual purple: a photosensitive purple-red chromoprotein in the retinal rods that is bleached to visual yellow (all-transretinal) by light, thereby stimulating retinal sensory endings. Lack of rhodopsin results in night blindness. Vitamin A is the primary source of rhodopsin.

rho·dop·sin

(rō-dop'sin), [MIM*180380]
A purplish-red thermolabile protein, MW about 40,000, found in the external segments of the rods of the retina; consists of opsin combined with 11-cis retinal; it is bleached by the action of light, which converts it to opsin and all-trans-retinal, and is restored in the dark by rhodogenesis; the dominant protein in the plasma membrane of rod cells.
Synonym(s): visual purple

rhodopsin

/rho·dop·sin/ (ro-dop´sin) visual purple; a photosensitive purple-red chromoprotein in the retinal rods that is bleached to visual yellow (all-trans retinal) by light, thereby stimulating retinal sensory endings.

rhodopsin

(rō-dŏp′sĭn)
n.
Any of a class of reddish, light-sensitive pigments found in the retinal rods of the eyes of terrestrial and marine vertebrates, consisting of opsin and retinal. Also called visual purple.

rhodopsin

[rōdop′sin]
Etymology: Gk, rhodon, rose, opsis, vision
the purple pigmented compound in the rods of the retina, formed by a protein, opsin, and a derivative of vitamin A, retinal. Rhodopsin gives the outer segments of the rods a purple color and adapts the eye to low-density light. The compound breaks down when struck by light, and this chemical change triggers the conduction of nerve impulses. Brief periods of darkness allow the opsin and the retinal to reconstitute the rhodopsin, which accounts for the short delay a person experiences in adapting to sudden or drastic changes in lighting, as when moving out of bright sunlight into a darkened room or from darkness into bright light. Closing the eyes is a natural reflex that allows reconstitution of rhodopsin. Compare iodopsin. See also visual purple.

rho·dop·sin

(rō-dop'sin)
A red thermolabile protein found in the rods of the retina; it is bleached by the action of light, which converts it to opsin and all-trans-retinal, and is restored in the dark by rhodogenesis; the dominant protein in the plasma membrane of rod cells.
Synonym(s): visual purple.

rhodopsin

The retinal rod photoreceptor pigment. Also known as visual purple.

rhodopsin

a photochemical pigment found in the rods of the retina of the vertebrate eye. When bleached by absorbed light, rhodopsin dissociates into its two components - a pigment called RETINAL and a protein called OPSIN. This dissociation ultimately triggers an action potential and the production of nerve impulses in the ganglion cells leading to the optic nerve. Lack of rhodopsin causes night blindness.

rhodopsin 

Visual pigment contained in the outer segments of the rod cells of the retina and involved in scotopic vision. When light stimulates the retina, the chromophore of the pigment molecule '11-cis' retinal (which is vitamin A aldehyde) isomerizes to 'all-trans' retinal. This leads to other chemical transformations which carry on even in the absence of light. The first stage is prelumirhodopsin, then lumirhodopsin and finally metarhodopsin (of which there are two types). This last transformation may lead to the breakdown of the molecule into retinal and opsin. The molecule is regenerated by recombining retinal and opsin with some enzymes. The absorption spectrum of rhodopsin has a maximum around 498 nm. The isomerization from '11-cis' to 'all-trans' also gives rise to the process of transduction in which the membrane potential covering the pigment molecules in the outer segment changes towards a hyperpolarization of the cell. This is the first step in the nervous response to a light stimulation of the retina. Syn. visual purple (not used any more); erythropsin. See dark adaptation; bleaching; receptor potential; absorption spectrum; transduction.

rho·dop·sin

(rō-dop'sin) [MIM*180380]
A red thermolabile protein found in the rods of the retina.
Synonym(s): visual purple.

rhodopsin (rōdop´sin),

n a purple light-receptive pigment found in the retina and consisting of opsin and retinal. Rhodopsin helps the eye adjust to drastic changes in environmental lighting.

rhodopsin

visual purple: a photosensitive purple-red chromoprotein in the retinal rods that is bleached to visual yellow (all-trans-retinal) by light, thereby stimulating retinal sensory endings. Lack of rhodopsin results in night blindness. Vitamin A is the primary source of rhodopsin.
References in periodicals archive ?
The program was accompanied with all-trans retinoic acid administration for a four-day protocol.
Characterization of acute promyelocytic leukaemia eases with PML-RAR alpha break/fusion sites in PML exon 6: identification of a subgroup with decreased in vitro responsiveness to all-trans retinoic acid.
To identify the effects of RA on adipocyte differentiation of bovine intramuscular fibroblast-like cells, cell differentiation was induced by the addition of differentiation medium in the absence or presence of 1 nM and 1 [micro]M all-trans RA (Figure 5).
All-trans retinoic acid (RA) and 9-cis-retinoic acid (9cRA) are activators of Retinoic Acid Receptors (RARs).
CYP26 inhibitors are expected to raise endogenous levels of both all-trans and 9-cis retinoic acid in cells expressing the enzyme and thereby activate both RAR and RXR nuclear receptor pathways in a cell- and tissue-specific fashion.
Based on the relative abundance of mRNA for RARs, as compared with RXRs, it is likely that all-trans retinoic acid, rather than 9-cis retinoic acid, plays a role in regulating scleral fibroblast function.
Tamibarotene is an orally available, rationally designed, synthetic retinoid compound that is 10-times more potent than all-trans retinoic acid (ATRA) and was designed to avoid several side effects of ATRA," said Daniel Levitt, MD, Ph.
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Kappa will market its novel, all-trans vitamin K product under the trade name K2VITAL.
Radiation-induced expression of E-selectin was also blocked by all-trans retinoic acid (at-RA), whereas 9-cis retinoic acid was ineffective.