WordNet

a special pigment found in the rods and cones of the retina
acquire pigment; become colored or imbued
any substance whose presence in plant or animal tissues produces a characteristic color
color or dye with a pigment; "pigment a photograph"
dry coloring material (especially a powder to be mixed with a liquid to produce paint, etc.)

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〈U〉〈C〉(おもに紛末の)絵の具,顔料 / 〈U〉色素
感光性の

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/10 10:58:19」(JST)

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Normalised absorption spectra of the three human photopsins and of human rhodopsin (dashed).

Photopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsin, the cone pigment system in chicken retina, is a close analog of the visual purple rhodopsin that is used in night vision. Iodopsin consists of the protein component and a bound chromophore, retinal.

Function

Opsins are Gn-x protein-coupled receptors of the retinylidene protein family. Isomerization of 11-cis-retinal into all-trans-retinal by light induces a conformational change in the protein that activates photopsin and promotes its binding to G protein transducin, which triggers a second messenger cascade.

Types

Different opsins differ in a few amino acids and absorb light at different wavelengths as retinal-bound pigments.

Cone type	Name	Range	Peak wavelength^[1]^[2]
S (OPN1SW) - "tritan", "cyanolabe"	β	400–500 nm	420–440 nm
M (OPN1MW) - "deutan", "chlorolabe"	γ	450–630 nm	534–545 nm
L (OPN1LW) - "protan", "erythrolabe"	ρ	500–700 nm	564–580 nm

In humans there are 3 different iodopsins (rhodopsin analogs) that contain the protein-pigment complexes photopsin I, II, and III. The 3 types of iodopsins are called erythrolabe(photopsin I + retinal), chlorolabe(photopsin II + retinal), and cyanolabe(photopsin III + retinal), respectively.^[3] These photopsins have absorption maxima for red ["erythr"-red] (photopsin I), green ["chlor"-green] (photopsin II), and bluish-violet light ["cyan"-bluish violet] (photopsin III).

History

George Wald received the 1967 Nobel Prize in Physiology or Medicine for his experiments in the 1950s that showed the difference in absorbance by these photopsins (see image).

References

^ Wyszecki, Günther; Stiles, W.S. (1982). Color Science: Concepts and Methods, Quantitative Data and Formulae (2nd ed.). New York: Wiley Series in Pure and Applied Optics. ISBN 0-471-02106-7.
^ R. W. G. Hunt (2004). The Reproduction of Colour (6th ed.). Chichester UK: Wiley–IS&T Series in Imaging Science and Technology. pp. 11–12. ISBN 0-470-02425-9.
^ Rushton, W. A. H. (1 June 1966). "Densitometry of pigments in rods and cones of normal and color defective subjects" (PDF). Investigative Ophthalmology 5 (3): 233–241. PMID 5296487. Retrieved 2006-11-14.

External links

Rhodopsin and the eye, an excellent summary with pictures.

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English Journal

Melanopsin is highly resistant to light and chemical bleaching in vivo.

Sexton TJ, Golczak M, Palczewski K, Van Gelder RN.SourceFrom the Departments of Ophthalmology and.
The Journal of biological chemistry.J Biol Chem.2012 Jun 15;287(25):20888-97. Epub 2012 Apr 30.
Melanopsin is the photopigment of mammalian intrinsically photosensitive retinal ganglion cells, where it contributes to light entrainment of circadian rhythms, and to the pupillary light response. Previous work has shown that the melanopsin photocycle is independent of that used by rhodopsin (Tu, D
PMID 22547062

Melanopsin and mechanisms of non-visual ocular photoreception.

Sexton T, Buhr E, Van Gelder RN.SourceDepartments of Ophthalmology and and Biological Structure, University of Washington School of Medicine, Seattle, Washington 98104, USA.
The Journal of biological chemistry.J Biol Chem.2012 Jan 13;287(3):1649-56. Epub 2011 Nov 10.
In addition to rods and cones, the mammalian eye contains a third class of photoreceptor, the intrinsically photosensitive retinal ganglion cell (ipRGC). ipRGCs are heterogeneous irradiance-encoding neurons that primarily project to non-visual areas of the brain. Characteristics of ipRGC light respo
PMID 22074930

Japanese Journal

Inheritance of Anthocyanin Pigment and Photosensitivity in Eggplant (Solanum melongena L.) Fruit

, ,
Environment control in biology 50(1), 75-80, 2012-03-30
… In addition, based on the results obtained under dark conditions, the genetic characteristic of photosensitivity in the major anthocyanins was segregated into the ratio of 9:3:3:1 (nasunin of the non-photosensitive type : nasunin of the photosensitive type: tulipanin of the non-photosensitive type: tulipanin of the photosensitive type). …
NAID 10030741810

Serum Vitamin A Level Measurement in Slaughtered and Live Cattle Using Multispectral Imaging

, , , , , , , , , ,
Engineering in Agriculture, Environment and Food 3(2), 42-46, 2010
… Since the photosensitive pigment rhodopsin has a maximum absorption of about 500 nm, the results suggest that 500 nm could be the optimum wavelength for measuring pupil reflection. …
NAID 130000255351

オプシンファミリーの分子進化と機能多様性

小柳光正
比較生理生化学 25(2), 50-57, 2008-04-20
　オプシンは, 視覚や概日リズムの光調節など動物の光受容システムの入り口に位置し, オプシンのアミノ酸配列に基づく性質が光受容の大部分の性質を決める。ほとんどの動物において複数のオプシン遺伝子が存在することが知られており, 多様なオプシンの機能を調べることは, 光受容システムの分子基盤やその進化を知る上で重要である。筆者らはオプシンの機能多様性を調べる目的で, ナメクジウオやヤツメウナギから …
NAID 10025616930