opsin


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Related to opsin: rhodopsin, opsonin, KIPRIS

op·sin

(op'sin),
The protein portion of the rhodopsin molecule; at least three separate opsins are located in cone cells.

opsin

/op·sin/ (op´sin) a protein of the retinal rods (scotopsin) and cones (photopsin) that combines with 11-cis -retinal to form visual pigments.

opsin

(ŏp′sĭn)
n.
Any of various light-sensitive proteins, especially one that is a constituent of a rhodopsin or other visual pigment found in the retina of the vertebrate eye.

opsin

a protein that combines with retinal to form visual pigments (rhodopsin and iodopsin) in the photoreceptor cells of the retina.

op·sin

(op'sin)
The protein portion of the rhodopsin molecule; at least three separate opsins are located in cone cells.

opsin

a protein that occurs in rods and cones of the RETINA of the eye, which combines with retinal 1 or retinal2 to form visual pigments.

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.

opsin (op´sin),

n a visual pigment protein found in the retinal rods.

opsin

the protein component of retinal pigments, e.g. rhodopsin.
References in periodicals archive ?
Opsin expression in Limulus eye photoreceptors: summary and perspectives
Scientists do not yet know for certain whether the body will detect the opsin proteins as foreign molecules and reject them.
Within the principal eyes, the LWS opsin Rhl was expressed in the two deepest (proximal) retinal layers, while the UVS opsin Rh3 was expressed in the distal two retinal layers (Nagata et al.
Opsins and compounds that work with opsins also show up in skin from the common and broadclub cuttlefishes (Sepia officinalis and S.
Summary: TEHRAN (FNA)- Opsins, the light-sensitive proteins key to vision, may have evolved earlier and undergone fewer genetic changes than previously believed.
34) The high degree of similarity and proximal positioning of the L- and M-cone pigment genes suggest that they are the result of a duplication of one opsin gene.
There is a growing body of evidence that extraretinal opsin expression is commonplace across many diverse animal phyla, although the physiological functions associated with these opsins remain elusive in many cases.
Thus, they challenge the idea that a comprehensive understanding of the light sensitivity of a tissue can be obtained by characterizing opsin expression alone.
This is caused by a mutation in the opsin gene, which is responsible for producing visual pigments for color vision.
His hypothesis was confirmed when his team discovered a new opsin light-sensitive protein, melanopsin, in the eye, made by a newly discovered photoreceptor, a photosensitive retinal ganglion cell (PRGC).