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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/07/17 18:09:30」(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. Cite uses deprecated parameters (help)
^ 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.

This cell biology article is a stub. You can help Wikipedia by expanding it.

English Journal

Long-wave sensitivity in the masked greenling (Hexagrammos octogrammus), a shallow-water marine fish.

Kondrashev SL.SourceLaboratory of Physiology, A.V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, 17 Palchevskogo Street, Vladivostok 690041, Russia. slk49@mail.ru
Vision research.Vision Res.2008 Sep;48(21):2269-74. doi: 10.1016/j.visres.2008.07.004. Epub 2008 Aug 21.
Microspectrophotometry (MSP) revealed that surprisingly for a "fully marine" species, in summer, photoreceptors of the nearshore scorpaeniform fish known as the masked greenling, Hexagrammos octogrammus, contained exclusively, or presumably, porphyropsin with a small admixture of rhodopsin. As a res
PMID 18675840

Presence of rhodopsin and porphyropsin in the eyes of 164 fishes, representing marine, diadromous, coastal and freshwater species--a qualitative and comparative study.

Toyama M, Hironaka M, Yamahama Y, Horiguchi H, Tsukada O, Uto N, Ueno Y, Tokunaga F, Seno K, Hariyama T.SourceDepartment of Biology, Faculty of Medicine, Hamamatsu University School of Medicine, Handayama, Hamamatsu, Japan.
Photochemistry and photobiology.Photochem Photobiol.2008 Jul-Aug;84(4):996-1002. doi: 10.1111/j.1751-1097.2008.00344.x. Epub 2008 Apr 14.
There are two types of visual pigments in fish eyes; most marine fishes have rhodopsin, while most freshwater fishes have porphyropsin. The biochemical basis for this dichotomy is the nature of the chromophores, retinal (A1) and 3-dehydroretinal (A2), each of which is bound by an opsin. In order to
PMID 18422881

Eel visual pigments revisited: the fate of retinal cones during metamorphosis.

Bowmaker JK, Semo M, Hunt DM, Jeffery G.SourceUCL Institute of Ophthalmology, University College London, London, United Kingdom. j.bowmaker@ucl.ac.uk
Visual neuroscience.Vis Neurosci.2008 May-Jun;25(3):249-55. doi: 10.1017/S0952523808080152. Epub 2008 Mar 6.
During their complex life history, anguilliform eels go through a major metamorphosis when developing from a fresh water yellow eel into a deep-sea silver eel. In addition to major changes in body morphology, the visual system also adapts from a fresh water teleost duplex retina with rods and cones,
PMID 18321400

Japanese Journal

水産上重要な通し回遊魚, サケ・マスの視覚メカニズムとその資源生物学的意味

長谷川英一
比較生理生化学 25(4), 156-164, 2008-11-20
　一生のうちに，川と海の間を往き来する魚を通し回遊魚（Diadromous fish）という。そのような魚種としてウナギ，アユ，サケ（シロサケ），ヨシノボリなどが挙げられる<SUP>11）</SUP>。淡水と海水という塩分濃度が著しく異なる水域を彼らは何故回遊するのであろうか。それを支える生体内でのメカニズムについては，内分泌系（ホルモン）や感覚神経系（嗅覚）の関与が解明 …
NAID 10025617218

Changes in rhodopsin-porphyropsin ratio of chum and pink salmon

HASEGAWA EI-ICHI
Fisheries science : FS 71(5), 1091-1097, 2005-10-01
NAID 10016375905

PORPHYROPSIN AND NEW DEEP-SEA VISUAL PIGMENT WITH 4-HYDROXYRETINAL ARE FOUND IN SOME MESOPELAGIC CEPHALOPODS IN ATLANTIC.(Physiology)Proceedings of the Sixty-Third Annual Meeting of the Zoologiacal Socistry of Japan