rhodopsin

rho·dop·sin

R0225100 (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.

[rhod(o)- + Greek opsis, sight; see -opsis + -in.]

rhodopsin

(rəʊˈdɒpsɪn) n (Biochemistry) a red pigment in the rods of the retina in vertebrates. It is dissociated by light into retinene, the light energy being converted into nerve signals, and is re-formed in the dark. Also called: visual purple See also iodopsin[C20: from rhodo- + -opsis + -in]

rho•dop•sin

(roʊˈdɒp sɪn)

n. a bright red photosensitive pigment found in the rod-shaped cells of the retina of certain fishes and most higher vertebrates: it is broken down by the action of dim light into retinal and opsin. [1885–90; rhod- + Greek óps(is) sight, vision + -in¹]

Thesaurus

Noun

rhodopsin - a red photopigment in the retinal rods of vertebrates; dissociates into retinene by lightretinal purple, visual purpleretinal rod, rod cell, rod - a visual receptor cell that is sensitive to dim lightopsin - retinal protein formed by the action of light on rhodopsinretinal, retinene - either of two yellow to red retinal pigments formed from rhodopsin by the action of lightphotopigment - a special pigment found in the rods and cones of the retina

Translations

Rhodopsin

rhodopsin

[rō′däp·sən] (biochemistry) A deep-red photosensitive pigment contained in the rods of the retina of marine fishes and most higher vertebrates. Also known as retinal pigment; visual purple.

Rhodopsin

(also visual purple), the main visual pigment contained in the retinal rods of vertebrates (with the exception of certain fishes and amphibians during their early stages of development) and invertebrates. Rhodopsin is a complex protein (chromoprotein) made up of 11-cis-retinal (chromophore), a glycoprotein, that is, a protein bonded to sugars, and lipids (the opsin part). The molecular weight of rhodopsin is approximately 40,000 in vertebrates and 70,000 in cephalopods. Rhodopsin forms an integral and highly organized part of the ultra-structure of rods.

The visual act begins with the absorption by rhodopsin of a quantum of light energy (the optimal absorption of rhodopsin is at approximately 500 nanometers). With absorption, isomerization of 11-cis-retinal to all-trans-retinal occurs:

The isomerization leads to a gradual decomposition (photolysis) of the rhodopsin molecule, a change in the ionic transfer in the photoreceptor, and the initiation of an electric signal, which is transmitted to the nerve elements of the retina.

Rhodopsin is regenerated either through the synthesis from 11-cis-retinal and the opsin liberated after photolysis or through the absorption of a second quantum of light energy by one of the intermediate products of photolysis. Regeneration can also occur during the synthesis of new retinal rod distal segments; this is the principal means of regeneration where rods are concerned (Figure 1).

Figure 1. Cycle of the principal changes undergone by rhodopsin in retinal rods

It has been found that the cell membranes of certain halophilic bacteria contain a pigment that is also composed of retinal, a glycoprotein, and lipids. This bacterial rhodopsin, whose structure is yet to be conclusively established, appears to participate in photosynthesis together with other bacterial pigments.

REFERENCES

Boroviagin, V. L., M. A. Ostrovskii, and I. B. Fedorovich. “Fotoretseptornaia membrana i nativnyi rodopsin.” Biofizika, 1971, vol. 16, no. 2.
Etingof, R. N., and I. A. Ostapenko. “Rodopsin: struktura i prevrashcheniia.” Uspekhi sovremennoi biologii, 1971, vol. 72, no. 2.

I. B. FEDORVICH

rhodopsin

enUK

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

(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.

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

rho·dop·sin

rhodopsin

rho•dop•sin

Rhodopsin

rhodopsin

Rhodopsin

REFERENCES

rhodopsin

rhodopsin

rho·dop·sin

rhodopsin

rho·dop·sin

rhodopsin

rhodopsin

rhodopsin

rho·dop·sin

rhodopsin

Synonyms for rhodopsin

noun a red photopigment in the retinal rods of vertebrates

Synonyms

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