Rodopsin

Rodopsin (opsin 2, štap pigment) (retinitis pigmentosa 4, autosomno dominantan)
	; Senzorni rodopsin II (duginih boja) smešten u lipidnom dvosloju (glave crveno i repovi plavo) sa transducinom ispod njega. Gtα je obojen crveno, Gtβ plavo, i Gtγ žuto. GDP molekul je vezan u Gtα-podjedinici i kovalento vezani retinal (crno ) je u rodopsinu. N-terminus rodopsina je crven i C-terminus je plav. Pretpostavljeno ankerisanje transducina za membranu je prikazano u crnoj boji.
Dostupne strukture
	1eds, 1edx, 1f88, 1gzm, 1hzx, 1jfp, 1l9h, 1ln6, 1u19, 2g87, 2hpy, 2i35, 2i36, 2i37
Identifikatori
Simboli	RHO; MGC138309; MGC138311; OPN2; RP4
Vanjski ID	OMIM: 180380 MGI: 97914 HomoloGene: 68068 GeneCards: RHO Gene
Ontologija gena
Molekularna funkcija	• rodopsinu-slična receptorska aktivnost; • receptorska aktivnost;
Celularna komponenta	• fotoreceptorski spoljašnji segment; • membrana plazme; • integralno sa membranom plazme;
Biološki proces	• signalni put G-protein spregnutog receptora; • vizuelna percepcija; • fototransdukcija, vidljiva svetlost; • rodopsin posredovana signalizacija; • protein-hromofor veza; • respons na stimulus;
Pregled RNK izražavanja
	podaci
Ortolozi

edit

Rodopsin, mrežnjačin purpur, je pigment retine koji je odgovoran za formiranje fotoreceptorskih ćelija, i za prve događaje u percepciji svetlosti. Rodopsini pripadaju familiji G-protein spregnutih receptora i ekstremno su senzitivni na svetlost, što omogućava vid u slabo-osvetljenoj sredini.^[1] Exposed to light, the pigment immediately photobleaches, and it takes about 30 minutes^[2] to regenerate fully in humans.

Struktura

Rodopsin se sastoji od proteinskog dela opsina i reverzibilno kovalentno vezanog kofaktor, retinala. Opsin, svežanj sedam transmembranskih heliksa međusobno povezanih proteinskim petljama, vezuje retinal (fotoreaktivni hromofor), koji je lociran u centralnoj šupljini na lizinskom ostatku sedmog heliksa. Retinal zauzima horizontalan položaj u odnosu na membranu. Svaki spoljašnji segment diska sadrži hiljade vizuelnih molekula pigmenta. Oko polovine opsina je unutar lipidnog dvosloja. Retinal nastaje u retini iz Vitamina A, dijetarnog beta-karotena. Izomerizacija 11-cis-retinala u sve-trans-retinal pod uticajem svetlosti indukuje konformacionu promenu (beljenje) u opsina, koja se nastavlja sa metarodopsinom II, koji aktivira vezani G protein transducin, i započinje kaskadu sekundarnih glasnika.^[2]^[3]^[4]

Rodopsin štapića najsnažnije apsorbuje zeleno-plavu svetlost, i zato izgleda crvenkasto-ljubičasto. On se naziva "vizuelno ljubičasto". Rodopsin je odgovoran za monohromatski vid u tami.^[2]

Nekoliko blisko srodnih opsina postoji. Oni se razlikuju u nekoliko aminokiselina, i konsekventno u talasnoj dužini svetlosti koju najjače apsorbuju. Kod čoveka postoje četiri različita opsina pored rodopsina. Fotopsini se nalazi u različitim tipovima koničnih ćelija retine, i oni su baza raspoznavanja boja. Oni imaju maksimume apsorpcije za žuto-zeleno (fotopsin I), zeleno (fotopsin II), i plavo-ljubičasto (fotopsin III) svetlo. Preostali opsin (melanopsin) se nalazi u fotosenzitivnim ganglionskim ćelijama, i apsorbuje najjače plavu svetlost.

Struktura rodopsina je detaljno proučena putem rendgenske strukturne analize kristala rodopsina. Fotoizomerizaciona dinamika je bila istražena putem FTIR spektroskopije i UV/Vis spektroskopije. Prvi fotoprodukt, fotorodopsin, se formira u toku 200 femtosekundi nakon iradijacije, čemu sledi u toku nekoliko pikosekundi drugi, batorodopsin, sa deformisanim sve-trans vezama. Taj intermedijar može da bude zarobljen i studiran na kriogenim temperaturama. Više modela (npr. mehanizam pedala bicikla, hula-tvist mehanizam) pokušava da objasni kako retinalna grupa može da promeni svoju konformaciju bez sudaranja sa okružujućim rodopsin proteinskim džepom.^[5]^[6]^[7]

Nedavni nalazi indiciraju da rodopsin funkcionače kao monomer, a ne kao dimer, mada je to dugo vremena bila ustaljena paradigma za G-spregnute proteinske receptore.^[8]

Reference

↑ Litmann BJ, Mitchell DC (1996). „Rhodopsin structure and function”. u: Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 1-32. ISBN 978-1-55938-659-3.
↑ ^2,0 ^2,1 ^2,2 Stuart JA, Brige RR (1996). „Characterization of the primary photochemical events in bacteriorhodopsin and rhodopsin”. u: Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 33-140. ISBN 978-1-55938-659-3.
↑ Hofmann KP, Heck M (1996). „Light-induced protein-protein interactions on the rod photoreceptor disc membrane”. u: Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 141-198. ISBN 978-1-55938-659-3.
↑ Kolb H, Fernandez E, Nelson R, Jones BW (1. 3. 2010.). „Webvision: Photoreceptors”. University of Utah. Arhivirano iz originala na datum 2000-08-16.
↑ Nakamichi H, Okada T (June 2006). „Crystallographic analysis of primary visual photochemistry”. Angew. Chem. Int. Ed. Engl. 45 (26): 4270-3. DOI:10.1002/anie.200600595. PMID 16586416.
↑ Schreiber M, Sugihara M, Okada T, Buss V (June 2006). „Quantum mechanical studies on the crystallographic model of bathorhodopsin”. Angew. Chem. Int. Ed. Engl. 45 (26): 4274-7. DOI:10.1002/anie.200600585. PMID 16729349.
↑ Weingart O (September 2007). „The twisted C11-C12 bond of the rhodopsin chromophore--a photochemical hot spot”. J. Am. Chem. Soc. 129 (35): 10618-9. DOI:10.1021/ja071793t. PMID 17691730.
↑ „Monomeric G-Protein-Coupled Receptor as a Functional Unit - Biochemistry (ACS Publications)”.

Literatura

Hofmann KP, Heck M (1996). Lee AG. ur. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 141-198.
Stuart JA, Brige RR (1996). Lee AG. ur. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 33-140.
Litmann BJ, Mitchell DC (1996). Lee AG. ur. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 1-32.
Humphries P, Kenna P, Farrar GJ (1992). „On the molecular genetics of retinitis pigmentosa.”. Science 256 (5058): 804-8. DOI:10.1126/science.1589761. PMID 1589761.
Edwards SC (1995). „Involvement of cGMP and calcium in the photoresponse in vertebrate photoreceptor cells.”. The Journal of the Florida Medical Association 82 (7): 485-8. PMID 7673885.
al-Maghtheh M, Gregory C, Inglehearn C, et al. (1993). „Rhodopsin mutations in autosomal dominant retinitis pigmentosa.”. Hum. Mutat. 2 (4): 249-55. DOI:10.1002/humu.1380020403. PMID 8401533.
Garriga P, Manyosa J (2002). „The eye photoreceptor protein rhodopsin. Structural implications for retinal disease.”. FEBS Lett. 528 (1-3): 17-22. DOI:10.1016/S0014-5793(02)03241-6. PMID 12297272.
Mendes HF, van der Spuy J, Chapple JP, Cheetham ME (2005). „Mechanisms of cell death in rhodopsin retinitis pigmentosa: implications for therapy.”. Trends in molecular medicine 11 (4): 177-85. DOI:10.1016/j.molmed.2005.02.007. PMID 15823756.
Inglehearn CF, Keen TJ, Bashir R, et al. (1993). „A completed screen for mutations of the rhodopsin gene in a panel of patients with autosomal dominant retinitis pigmentosa.”. Hum. Mol. Genet. 1 (1): 41-5. DOI:10.1093/hmg/1.1.41. PMID 1301135.
Farrar GJ, Findlay JB, Kumar-Singh R, et al. (1993). „Autosomal dominant retinitis pigmentosa: a novel mutation in the rhodopsin gene in the original 3q linked family.”. Hum. Mol. Genet. 1 (9): 769-71. DOI:10.1093/hmg/1.9.769. PMID 1302614.
Robinson PR, Cohen GB, Zhukovsky EA, Oprian DD (1992). „Constitutively active mutants of rhodopsin.”. Neuron 9 (4): 719-25. DOI:10.1016/0896-6273(92)90034-B. PMID 1356370.
Fujiki K, Hotta Y, Hayakawa M, et al. (1992). „Point mutations of rhodopsin gene found in Japanese families with autosomal dominant retinitis pigmentosa (ADRP).”. Jpn. J. Hum. Genet. 37 (2): 125-32. DOI:10.1007/BF01899733. PMID 1391967.
Olsson JE, Gordon JW, Pawlyk BS, et al. (1992). „Transgenic mice with a rhodopsin mutation (Pro23His): a mouse model of autosomal dominant retinitis pigmentosa.”. Neuron 9 (5): 815-30. DOI:10.1016/0896-6273(92)90236-7. PMID 1418997.
Andréasson S, Ehinger B, Abrahamson M, Fex G (1993). „A six-generation family with autosomal dominant retinitis pigmentosa and a rhodopsin gene mutation (arginine-135-leucine).”. Ophthalmic paediatrics and genetics 13 (3): 145-53. DOI:10.3109/13816819209046483. PMID 1484692.
Inglehearn CF, Lester DH, Bashir R, et al. (1992). „Recombination between rhodopsin and locus D3S47 (C17) in rhodopsin retinitis pigmentosa families.”. Am. J. Hum. Genet. 50 (3): 590-7. PMC 1684283. PMID 1539595.
Fishman GA, Stone EM, Gilbert LD, Sheffield VC (1992). „Ocular findings associated with a rhodopsin gene codon 106 mutation. Glycine-to-arginine change in autosomal dominant retinitis pigmentosa.”. Arch. Ophthalmol. 110 (5): 646-53. PMID 1580841.
Keen TJ, Inglehearn CF, Lester DH, et al. (1992). „Autosomal dominant retinitis pigmentosa: four new mutations in rhodopsin, one of them in the retinal attachment site.”. Genomics 11 (1): 199-205. DOI:10.1016/0888-7543(91)90119-Y. PMID 1765377.
Dryja TP, Hahn LB, Cowley GS, et al. (1991). „Mutation spectrum of the rhodopsin gene among patients with autosomal dominant retinitis pigmentosa.”. Proc. Natl. Acad. Sci. U.S.A. 88 (20): 9370-4. DOI:10.1073/pnas.88.20.9370. PMC 52716. PMID 1833777.
Gal A, Artlich A, Ludwig M, et al. (1992). „Pro-347-Arg mutation of the rhodopsin gene in autosomal dominant retinitis pigmentosa.”. Genomics 11 (2): 468-70. DOI:10.1016/0888-7543(91)90159-C. PMID 1840561.
Sung CH, Davenport CM, Hennessey JC, et al. (1991). „Rhodopsin mutations in autosomal dominant retinitis pigmentosa.”. Proc. Natl. Acad. Sci. U.S.A. 88 (15): 6481-5. DOI:10.1073/pnas.88.15.6481. PMC 52109. PMID 1862076.
Jacobson SG, Kemp CM, Sung CH, Nathans J (1991). „Retinal function and rhodopsin levels in autosomal dominant retinitis pigmentosa with rhodopsin mutations.”. Am. J. Ophthalmol. 112 (3): 256-71. PMID 1882937.
Sheffield VC, Fishman GA, Beck JS, et al. (1991). „Identification of novel rhodopsin mutations associated with retinitis pigmentosa by GC-clamped denaturing gradient gel electrophoresis.”. Am. J. Hum. Genet. 49 (4): 699-706. PMC 1683182. PMID 1897520.
Kolb H, Fernandez E, Nelson R, Jones BW (1. 3. 2010.). „Webvision Home Page: The organization of the retina and visual system”. University of Utah.

Vanjske veze

MeSH Rhodopsin
Rodopsin protein
Fotoizomerizacija rodopsina Arhivirano 2006-10-05 na Wayback Machine-u
Rodopsin i oko
UMich orijentacija proteina u membranama families/superfamily-6

[Litmann_1996-1] Litmann BJ, Mitchell DC (1996). „Rhodopsin structure and function”. u: Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 1-32. ISBN 978-1-55938-659-3.

[Stuart_1996-2] 2,0 ^2,1 ^2,2 Stuart JA, Brige RR (1996). „Characterization of the primary photochemical events in bacteriorhodopsin and rhodopsin”. u: Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 33-140. ISBN 978-1-55938-659-3.

[Hofmann_1996-3] Hofmann KP, Heck M (1996). „Light-induced protein-protein interactions on the rod photoreceptor disc membrane”. u: Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. str. 141-198. ISBN 978-1-55938-659-3.

[4] Kolb H, Fernandez E, Nelson R, Jones BW (1. 3. 2010.). „Webvision: Photoreceptors”. University of Utah. Arhivirano iz originala na datum 2000-08-16.

[pmid16586416-5] Nakamichi H, Okada T (June 2006). „Crystallographic analysis of primary visual photochemistry”. Angew. Chem. Int. Ed. Engl. 45 (26): 4270-3. DOI:10.1002/anie.200600595. PMID 16586416.

[pmid16729349-6] Schreiber M, Sugihara M, Okada T, Buss V (June 2006). „Quantum mechanical studies on the crystallographic model of bathorhodopsin”. Angew. Chem. Int. Ed. Engl. 45 (26): 4274-7. DOI:10.1002/anie.200600585. PMID 16729349.

[pmid17691730-7] Weingart O (September 2007). „The twisted C11-C12 bond of the rhodopsin chromophore--a photochemical hot spot”. J. Am. Chem. Soc. 129 (35): 10618-9. DOI:10.1021/ja071793t. PMID 17691730.

[8] „Monomeric G-Protein-Coupled Receptor as a Functional Unit - Biochemistry (ACS Publications)”.

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