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a violet photopigment in the retinal cones of the eyes of most vertebrates; plays a role in daylight vision

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/28 21:19:05」(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.

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

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1. ビタミンAの概要 overview of vitamin a

English Journal

Thermal recovery of iodopsin from photobleaching intermediates.

Imamoto Y, Shichida Y.SourceDepartment of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan. imamoto@vision-kyoto-u.jp
Photochemistry and photobiology.Photochem Photobiol.2008 Jul-Aug;84(4):941-8. doi: 10.1111/j.1751-1097.2008.00332.x. Epub 2008 Apr 9.
The chloride effect on the photobleaching process of iodopsin, a chicken red-sensitive cone visual pigment, was studied in detail by time-resolved low-temperature spectroscopy at -40 degrees C to -10 degrees C. Decay-associated difference spectra obtained by kinetic analysis using the singular value
PMID 18399920

Circadian clockwork machinery in neural retina: evidence for the presence of functional clock components in photoreceptor-enriched chick retinal cell cultures.

Chaurasia SS, Pozdeyev N, Haque R, Visser A, Ivanova TN, Iuvone PM.SourceDepartment of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Molecular vision.Mol Vis.2006 Mar 30;12:215-23.
PURPOSE: Circadian clocks in retinas regulate a variety of biochemical and physiological processes. Retinal neurons, particularly photoreceptor cells, are thought to contain autonomous circadian clocks that control iodopsin expression, cFos expression, cAMP levels, and melatonin synthesis. Photorece
PMID 16604054

Japanese Journal

視物質における吸収波長制御機構 : アニオンによる制御を中心として

平野貴弘,七田芳則
生物物理 41(6), 284-289, 2001-11-25
我々が色を識別できるのは, 眼の中に吸収波長の異なる複数の視物質が含まれているからである.視物質の吸収波長は, 一般には発色団レチナールを取り囲むアミノ酸残基の性質によって決定される.しかし, 視物質グループの中には, CI-イオンを結合することで吸収波長をさらに長波長にシフトさせているものもある.本稿ではCI-イオンによる波長シフトの機構を含めて, 視物質の吸収波長制御機構に関する最近の知見を紹 …
NAID 110001155713

1PB029 同位体ラベルレチナールを用いたアイオドプシンの発色団の構造解析

平野貴弘,今井啓雄,神取秀樹,七田芳則,藤岡直子,和田昭盛,伊藤允好
生物物理 39(SUPPLEMENT1), S77, 1999-09-02
NAID 110001159042

Related Pictures

★リンクテーブル★

リンク元	「網膜」「ヨードプシン」

「網膜」

　　[★]

英: retina
関: 眼、眼球

図：SP.275,

組織学

10層よりなる (SP.275)

構造	層		細胞体
脈絡膜
網膜
1	色素上皮層		色素上皮細胞	pigment epithelium cell
2	杆体錐体層	rod and cone layer
3	外境界膜
4	外顆粒層	outer nuclear layer	視細胞	photoreceptor
5	外網状層	outer plexiform layer
6	内顆粒層	inner nuclear layer	双極細胞	bipolar cell
			水平細胞	horizontal cell
			アマクリン細胞	amacrine cell
7	内網状層	inner plexiform layer
8	神経節細胞層	ganglion cell layer	神経節細胞	ganglion cell
9	神経線維層	optic nerve fiber layer
10	内境界膜

視細胞層(外顆粒層)には以下の細胞が存在

杆状体細胞　明暗　ロドプシン　　 rhodopsin　＝　オプシン(opsin)　　　　　＋　レチナール(retinal)
錐状体細胞　色覚　ヨードプシン　 iodopsin　＝　フォトプシン(photopsin)　＋　レチナール(retinal)

感覚網膜(神経上皮)　＋　網膜色素上皮　の２つの上皮からなる。

臨床関連

黄斑変性症
網脈絡膜変性疾患

網膜色素変性症

「ヨードプシン」

　　[★]

英: iodopsin
同: アイオドプシン

[show details]

アイオドプシン : 約 611 件
ヨードプシン : 約 679 件

[Wyszecki-1] 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.

[2] 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.

[3] 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.

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iodopsin