View source for Rhodopsin

{{About|the visual rhodopsin of vertebrates|other types of rhodopsin|retinylidene protein}}
{{Infobox gene}}

'''Rhodopsin''' (also known as '''visual purple''') is a [[light]]-sensitive [[receptor protein]] involved in [[visual phototransduction]]. It is named after ancient Greek ῥόδον (rhódon) for "rose", due to its pinkish color, and ὄψις (ópsis) for "sight".<ref name="Perception_2008">{{citation | author = Perception | title = Guest Editorial Essay | edition = | publisher = Perception | location = | year = 2008 | origyear = | pages = 1 | quote = | isbn = | chapter = | doi = | url = | accessdate = }}</ref> Rhodopsin is a [[biological pigment]] found in the [[rod cell|rods]] of the [[retina]] and is a  [[G protein-coupled receptor|G-protein-coupled receptor]] (GPCR). Rhodopsin is extremely sensitive to light, and thus enables vision in low-light conditions.<ref name="Litmann_1996">{{cite book |vauthors=Litmann BJ, Mitchell DC | editor = Lee AG | title = Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set) | edition = | publisher = JAI Press | location = Greenwich, Conn | year = 1996 | origyear = | pages = 1–32 | quote = | isbn = 1-55938-659-2 | chapter = Rhodopsin structure and function | doi = | url = | accessdate = }}</ref>  When rhodopsin is exposed to light, it immediately [[Photobleaching|photobleaches]]. In humans, it is regenerated fully in about 30 minutes; after which rods are more sensitive.<ref name="Stuart_1996">{{cite book |vauthors=Stuart JA, Brige RR | editor = Lee AG | title = Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set) | edition = | publisher = JAI Press | location = Greenwich, Conn | year = 1996 | origyear = | pages = 33–140 | quote = | isbn = 1-55938-659-2 | chapter = Characterization of the primary photochemical events in bacteriorhodopsin and rhodopsin | doi = | url = | accessdate = }}</ref>

Rhodopsin was discovered by [[Franz Christian Boll]] in 1876.<ref>{{cite book|title=Encyclopedia of the Neurological Sciences|url=https://books.google.com/books?id=hfjSVIWViRUC&pg=PA441|date=29 April 2014|publisher=Academic Press|isbn=978-0-12-385158-1|pages=441–}}</ref><ref name="Giese2013">{{cite book|last=Giese|first=Arthur C.|title=Photophysiology: General Principles; Action of Light on Plants|url=https://books.google.com/books?id=16zSBAAAQBAJ&pg=PA9|accessdate=23 September 2015|date=24 September 2013|publisher=Elsevier|isbn=978-1-4832-6227-7|page=9}}</ref>

== Structure ==
Rhodopsin consists of two components, a [[protein molecule]] also called scotopsin and a [[covalent]]ly-bound [[Cofactor (biochemistry)|cofactor]] called [[retinal]]. Scotopsin is an [[opsin]], a light-sensitive [[G protein coupled receptor]] that embeds in the [[lipid bilayer]] of cell membranes using seven protein [[transmembrane domain]]s. These domains form a pocket where the photoreactive [[chromophore]], retinal, lies horizontally to the cell membrane, linked to a [[lysine]] residue in the seventh transmembrane domain of the protein. Thousands of rhodopsin molecules are found in each outer segment disc of the host rod cell. Retinal is produced in the [[retina]] from [[vitamin A]], from dietary [[beta-carotene]]. [[Isomerization]] of 11-''cis''-retinal into all-''trans''-retinal by [[light]] sets off a series of conformational changes ('bleaching') in the opsin, eventually leading it to a form called metarhodopsin II (Meta II), which activates an associated [[G protein]], [[transducin]], to trigger a cyclic [[guanosine monophosphate]] (cGMP) [[second messenger]] cascade.<ref name="Stuart_1996"/><ref name="Hofmann_1996">{{cite book |vauthors=Hofmann KP, Heck M | editor = Lee AG | title = Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set) | edition = | publisher = JAI Press | location = Greenwich, Conn | year = 1996 | origyear = | pages = 141–198 | quote = | isbn = 1-55938-659-2 | chapter = Light-induced protein-protein interactions on the rod photoreceptor disc membrane | doi = | url = | accessdate = }}</ref><ref>{{cite web | url = http://webvision.med.utah.edu/photo1.html| title = Webvision: Photoreceptors|vauthors=Kolb H, Fernandez E, Nelson R, Jones BW | date = 2010-03-01 | work = | publisher = University of Utah | pages = | archiveurl = | archivedate = | quote = | accessdate = }}</ref>

Rhodopsin of the [[rod cell|rod]]s most strongly absorbs green-blue light and, therefore, appears reddish-purple, which is why it is also called "visual purple".<ref>{{cite web|last1=Rogers|first1=Kara|title=Rhodopsin|url=http://www.britannica.com/science/rhodopsin|website=Encyclopædia Britannica|publisher=Britannica.com|accessdate=30 January 2016}}</ref> It is responsible for ''monochromatic'' vision in the dark.<ref name="Stuart_1996"/>

[[Image:Bovine rhodopsin.png|thumb|left|200px|Bovine rhodopsin]]
Several closely related opsins exist that differ only in a few [[amino acid]]s and in the [[wavelength]]s of light that they absorb most strongly. Humans have eight different other opsins besides rhodopsin, as well as [[cryptochrome]] (light-sensitive, but not an opsin).<ref name="Terakita2005">{{cite journal|last1=Terakita|first1=Akihisa|title=The opsins|journal=Genome Biology|volume=6|issue=3|year=2005|pages=213|url=http://www.genomebiology.com/content/6/3/213|issn=1465-6906|doi=10.1186/gb-2005-6-3-213|pmid=15774036|pmc=1088937}}</ref><ref name="FoleyGegear2011">{{cite journal|last1=Foley|first1=Lauren E.|last2=Gegear|first2=Robert J.|last3=Reppert|first3=Steven M.|title=Human cryptochrome exhibits light-dependent magnetosensitivity|journal=Nature Communications|volume=2|year=2011|pages=356|url=http://www.nature.com/ncomms/journal/v2/n6/full/ncomms1364.html|issn=2041-1723|doi=10.1038/ncomms1364|pmid=21694704|pmc=3128388}}</ref>

The [[photopsin]]s are found in the different types of the [[cone cell]]s of the retina and are the basis of [[color vision]]. They have absorption maxima for yellowish-green (photopsin I), green (photopsin II), and bluish-violet (photopsin III) light. The remaining opsin ([[melanopsin]]) is found in [[photosensitive ganglion cell]]s and absorbs blue light most strongly.

In rhodopsin, the aldehyde group of retinal is covalently linked to the amino group of a lysine residue on the protein in a protonated [[Schiff base]] (-NH+=CH-).<ref>{{cite journal | vauthors = Bownds D, Wald G | title = Reaction of the rhodopsin chromophore with sodium borohydride | journal = Nature | volume = 205 | pages = 254–7 | date = Jan 1965 | pmid = 14270706 | doi = 10.1038/205254a0 }}</ref> When rhodopsin absorbs light, its retinal cofactor isomerizes from the 11-cis to the all-trans configuration, and the protein subsequently undergoes a series of relaxations to accommodate the altered shape of the isomerized cofactor. The intermediates formed during this process were first investigated in the laboratory of [[George Wald]], who received the Nobel prize for this research in 1967.<ref name=WaldNobelPrize>{{cite web|last1=The Nobel Foundation|title=The Nobel Prize in Physiology or Medicine 1967|url=https://www.nobelprize.org/nobel_prizes/medicine/laureates/1967/|website=Nobelprize.org|publisher=Nobel Media AB 2014|accessdate=12 December 2015}}</ref> The photoisomerization dynamics has been subsequently investigated with time-resolved [[IR spectroscopy]] and [[UV/Vis]] spectroscopy. A first photoproduct called '''photorhodopsin''' forms within 200 [[femtosecond]]s after irradiation, followed within [[picosecond]]s by a second one called '''bathorhodopsin''' with distorted all-trans bonds. This intermediate can be trapped and studied at [[cryogenic]] temperatures, and was initially referred to as prelumirhodopsin.<ref>{{cite journal | vauthors = Yoshizawa T, Wald G | title = Pre-lumirhodopsin and the bleaching of visual pigments | journal = Nature | volume = 197 | issue = Mar 30 | pages = 1279–86 | date = March 1963 | pmid = 14002749 | doi = 10.1038/1971279a0 }}</ref> In subsequent intermediates lumirhodopsin and metarhodopsin I, the Schiff's base linkage to all-trans retinal remains protonated, and the protein retains its reddish color.  The critical change that initiates the neuronal excitation involves the conversion of metarhodopsin I to metarhodopsin II, which is associated with deprotonation of the Schiff's base and change in color from red to yellow.<ref>{{cite journal | vauthors = Matthews RG, Hubbard R, Brown PK, Wald G | title = Tautomeric forms of metarhodopsin | journal = The Journal of General Physiology | volume = 47 | pages = 215–40 | date = November 1963 | pmid = 14080814 | doi=10.1085/jgp.47.2.215 | pmc=2195338}}</ref> 
The structure of rhodopsin has been studied in detail via [[x-ray crystallography]] on rhodopsin crystals. Several models (e.g., the ''bicycle-pedal mechanism'', ''hula-twist mechanism'') attempt to explain how the retinal group can change its conformation without clashing with the enveloping rhodopsin protein pocket.<ref name="pmid16586416">{{cite journal | vauthors = Nakamichi H, Okada T | title = Crystallographic analysis of primary visual photochemistry | journal = Angewandte Chemie | volume = 45 | issue = 26 | pages = 4270–3 | date = June 2006 | pmid = 16586416 | doi = 10.1002/anie.200600595 }}</ref><ref name="pmid16729349">{{cite journal | vauthors = Schreiber M, Sugihara M, Okada T, Buss V | title = Quantum mechanical studies on the crystallographic model of bathorhodopsin | journal = Angewandte Chemie | volume = 45 | issue = 26 | pages = 4274–7 | date = June 2006 | pmid = 16729349 | doi = 10.1002/anie.200600585 }}</ref><ref name="pmid17691730">{{cite journal | vauthors = Weingart O | title = The twisted C11=C12 bond of the rhodopsin chromophore--a photochemical hot spot | journal = Journal of the American Chemical Society | volume = 129 | issue = 35 | pages = 10618–9 | date = September 2007 | pmid = 17691730 | doi = 10.1021/ja071793t }}</ref>

Recent data support that it is a functional monomer, instead of a dimer, which was the paradigm of G-protein-coupled receptors for many years.<ref name="pmid15996094">{{cite journal | vauthors = Chabre M, le Maire M | title = Monomeric G-protein-coupled receptor as a functional unit | journal = Biochemistry | volume = 44 | issue = 27 | pages = 9395–403 | date = July 2005 | pmid = 15996094 | doi = 10.1021/bi050720o }}</ref>

== Phototransduction ==
Rhodopsin is an essential G-protein coupled receptor in [[phototransduction]].

=== Function ===
The product of light activation, Metarhodopsin II, initiates the [[visual phototransduction]] pathway by stimulating the G protein [[transducin]] (G<sub>t</sub>), resulting in the liberation of its α subunit. This GTP-bound subunit in turn [[cyclic nucleotide phosphodiesterase#Activation by Tα|activates]] [[cyclic nucleotide phosphodiesterase|cGMP phosphodiesterase]]. cGMP phosphodiesterase hydrolyzes (breaks down) [[cyclic guanosine monophosphate|cGMP]], lowering its local concentration so it can no longer activate cGMP-dependent [[cation channel]]s.  This leads to the hyperpolarization of photoreceptor cells, changing the rate at which they release transmitters.

=== Deactivation ===
Meta II is deactivated rapidly after activating transducin by [[kinase|rhodopsin kinase]] and [[arrestin]].<ref name="pmid12427735">{{cite journal | vauthors = Heck M, Schädel SA, Maretzki D, Bartl FJ, Ritter E, Palczewski K, Hofmann KP | title = Signaling states of rhodopsin. Formation of the storage form, metarhodopsin III, from active metarhodopsin II | journal = The Journal of Biological Chemistry | volume = 278 | issue = 5 | pages = 3162–9 | date = Jan 2003 | pmid = 12427735 | pmc = 1364529 | doi = 10.1074/jbc.M209675200 }}</ref> Rhodopsin pigment must be regenerated for further phototransduction to occur. This means replacing all-trans-retinal with 11-cis-retinal and the decay of Meta II is crucial in this process. During the decay of Meta II, the Schiff base link that normally holds all-trans-retinal and the apoprotein opsin is hydrolyzed and becomes Meta III. In the rod outer segment, Meta III decays into separate all-trans-retinal and opsin.<ref name="pmid12427735"/> A second product of Meta II decay is an all-trans-retinal opsin complex in which the all-trans-retinal has been translocated to second binding sites. Whether the Meta II decay runs into Meta III or the all-trans-retinal opsin complex seems to depend on the pH of the reaction. Higher pH tends to drive the decay reaction towards Meta III.<ref name="pmid12427735"/>

== Retinal disease ==
Mutation of the rhodopsin gene is a major contributor to various retinopathies such as [[retinitis pigmentosa]]. In general, the disease-causing protein aggregates with [[ubiquitin]] in inclusion bodies, disrupts the intermediate filament network, and impairs the ability of the cell to degrade non-functioning proteins, which leads to photoreceptor [[apoptosis]].<ref name="pmid12082151">{{cite journal | vauthors = Saliba RS, Munro PM, Luthert PJ, Cheetham ME | title = The cellular fate of mutant rhodopsin: quality control, degradation and aggresome formation | journal = Journal of Cell Science | volume = 115 | issue = Pt 14 | pages = 2907–18 | date = July 2002 | pmid = 12082151 | url = http://jcs.biologists.org/cgi/pmidlookup?view=long&pmid=12082151 }}</ref> Other mutations on rhodopsin lead to [[X-linked congenital stationary night blindness]], mainly due to constitutive activation, when the mutations occur around the chromophore binding pocket of rhodopsin.<ref name="pmid15823756">{{cite journal | vauthors = Mendes HF, van der Spuy J, Chapple JP, Cheetham ME | title = Mechanisms of cell death in rhodopsin retinitis pigmentosa: implications for therapy | journal = Trends in Molecular Medicine | volume = 11 | issue = 4 | pages = 177–85 | date = April 2005 | pmid = 15823756 | doi = 10.1016/j.molmed.2005.02.007 }}</ref> Several other pathological states relating to rhodopsin have been discovered including poor post-Golgi trafficking, dysregulative activation, rod outer segment instability and arrestin binding.<ref name="pmid15823756"/>

== Microbial rhodopsins ==
{{Main|Microbial rhodopsin}}

Some [[prokaryote]]s express [[proton pump]]s called [[bacteriorhodopsin]]s, [[archaerhodopsin]]s, [[proteorhodopsin]]s, and [[xanthorhodopsin]]s to carry out [[phototrophy]].<ref name="pmid16997562">{{cite journal | vauthors = Bryant DA, Frigaard NU | title = Prokaryotic photosynthesis and phototrophy illuminated | journal = Trends in Microbiology | volume = 14 | issue = 11 | pages = 488–96 | date = November 2006 | pmid = 16997562 | doi = 10.1016/j.tim.2006.09.001 }}</ref> Like animal visual pigments, these contain a retinal chromophore (although it is an all-''trans'', rather than 11-''cis'' form) and have seven [[transmembrane helix|transmembrane alpha helices]]; however, they are not coupled to a G protein. Prokaryotic [[halorhodopsin]]s are light-activated chloride pumps.<ref name="pmid16997562"/> Unicellular flagellate algae contain [[channelrhodopsin]]s that act as light-gated cation channels when expressed in heterologous systems. Many other pro- and eukaryotic organisms (in particular, fungi such as ''Neurospora'') express rhodopsin ion pumps or sensory rhodopsins of yet-unknown function. Very recently, a microbial rhodopsin with [[guanylyl cyclase]] activity has been discovered.<ref name="Gao2015">{{cite journal | vauthors = Gao SQ, Nagpal J, Schneider MW, Kozjak-Pavlovic V, Nagel G, Gottschalk A | title = Optogenetic manipulation of cGMP in cells and animals by the tightly light-regulated guanylyl-cyclase opsin CyclOp | journal = Nature Communications | volume = 6 | issue = 8046 | date = July 2015 | doi = 10.1038/ncomms9046 | pmid=26345128 | pmc=4569695}}</ref><ref name="Scheib2015">{{cite journal | vauthors = Scheib U, Stehfest K, Gee CE, Körschen HG, Fudim R, Oertner TG, Hegemann P | title = The rhodopsin-guanylyl cyclase of the aquatic fungus Blastocladiella emersonii enables fast optical control of cGMP signaling | journal = Science Signaling | volume = 8 | issue = 389 | pages = rs8 | date = August 2015 | pmid = 26268609 | doi = 10.1126/scisignal.aab0611 }}</ref>  While all microbial rhodopsins have significant [[sequence homology]] to one another, they have no detectable sequence homology to the [[G protein-coupled receptor|G-protein-coupled receptor]] (GPCR) family to which animal visual rhodopsins belong. Nevertheless, microbial rhodopsins and GPCRs are possibly evolutionarily related, based on the similarity of their three-dimensional structures. Therefore, they have been assigned to the same superfamily in [[Structural Classification of Proteins]] (SCOP).<ref name="url_SCOP">{{cite web | url = http://scop.mrc-lmb.cam.ac.uk/scop/data/scop.b.g.e.b.html | title = Superfamily: Bacterial photosystem II reaction centre, L and M subunits | work = SCOP | accessdate = }}</ref>

== References ==
{{Reflist|33em}}

== Further reading ==
{{Refbegin|33em}}
* {{cite journal |last=|first=| date = May 1992 |year=| title = On the molecular genetics of retinitis pigmentosa |url=| journal = Science | volume = 256 | issue = 5058 | pages = 804–8 | doi = 10.1126/science.1589761 | pmid = 1589761 |via=| vauthors = Humphries P, Kenna P, Farrar GJ }}
* {{cite journal |last=|first=| date = July 1995 |year=| title = Involvement of cGMP and calcium in the photoresponse in vertebrate photoreceptor cells |url=| journal = The Journal of the Florida Medical Association | volume = 82 | issue = 7 | pages = 485–8 | doi =  | pmid = 7673885 |via=| vauthors = Edwards SC }}
* {{cite journal |last=|first=| year = 1993 | title = Rhodopsin mutations in autosomal dominant retinitis pigmentosa |url=| journal = Human Mutation | volume = 2 | issue = 4 | pages = 249–55 | doi = 10.1002/humu.1380020403 | pmid = 8401533 |via=| vauthors = al-Maghtheh M, Gregory C, Inglehearn C, Hardcastle A, Bhattacharya S }}
* {{cite journal |last=|first=| date = September 2002 |year=| title = The eye photoreceptor protein rhodopsin. Structural implications for retinal disease |url=| journal = FEBS Letters | volume = 528 | issue = 1–3 | pages = 17–22 | doi = 10.1016/S0014-5793(02)03241-6 | pmid = 12297272 |via=| vauthors = Garriga P, Manyosa J }}
* 
* {{cite journal |last=|first=| date = April 1992 |year=| title = A completed screen for mutations of the rhodopsin gene in a panel of patients with autosomal dominant retinitis pigmentosa |url=| journal = Human Molecular Genetics | volume = 1 | issue = 1 | pages = 41–5 | doi = 10.1093/hmg/1.1.41 | pmid = 1301135 |via=| vauthors = Inglehearn CF, Keen TJ, Bashir R, Jay M, Fitzke F, Bird AC, Crombie A, Bhattacharya S }}
* {{cite journal |last=|first=| date = December 1992 |year=| title = Autosomal dominant retinitis pigmentosa: a novel mutation in the rhodopsin gene in the original 3q linked family |url=| journal = Human Molecular Genetics | volume = 1 | issue = 9 | pages = 769–71 | doi = 10.1093/hmg/1.9.769 | pmid = 1302614 |via=| vauthors = Farrar GJ, Findlay JB, Kumar-Singh R, Kenna P, Humphries MM, Sharpe E, Humphries P }}
* {{cite journal |last=|first=| date = October 1992 |year=| title = Constitutively active mutants of rhodopsin |url=| journal = Neuron | volume = 9 | issue = 4 | pages = 719–25 | doi = 10.1016/0896-6273(92)90034-B | pmid = 1356370 |via=| vauthors = Robinson PR, Cohen GB, Zhukovsky EA, Oprian DD }}
* {{cite journal |last=|first=| date = June 1992 |year=| title = Point mutations of rhodopsin gene found in Japanese families with autosomal dominant retinitis pigmentosa (ADRP) |url=| journal = The Japanese Journal of Human Genetics | volume = 37 | issue = 2 | pages = 125–32 | doi = 10.1007/BF01899733 | pmid = 1391967 |via=| vauthors = Fujiki K, Hotta Y, Hayakawa M, Sakuma H, Shiono T, Noro M, Sakuma T, Tamai M, Hikiji K, Kawaguchi R }}
* {{cite journal |last=|first=| date = November 1992 |year=| title = Transgenic mice with a rhodopsin mutation (Pro23His): a mouse model of autosomal dominant retinitis pigmentosa |url=| journal = Neuron | volume = 9 | issue = 5 | pages = 815–30 | doi = 10.1016/0896-6273(92)90236-7 | pmid = 1418997 |via=| vauthors = Olsson JE, Gordon JW, Pawlyk BS, Roof D, Hayes A, Molday RS, Mukai S, Cowley GS, Berson EL, Dryja TP }}
* {{cite journal |last=|first=| date = September 1992 |year=| title = A six-generation family with autosomal dominant retinitis pigmentosa and a rhodopsin gene mutation (arginine-135-leucine) |url=| journal = Ophthalmic Paediatrics and Genetics | volume = 13 | issue = 3 | pages = 145–53 | doi = 10.3109/13816819209046483 | pmid = 1484692 |via=| vauthors = Andréasson S, Ehinger B, Abrahamson M, Fex G }}
* {{cite journal |last=|first=| date = March 1992 |year=| title = Recombination between rhodopsin and locus D3S47 (C17) in rhodopsin retinitis pigmentosa families |url=| journal = American Journal of Human Genetics | volume = 50 | issue = 3 | pages = 590–7 | doi =  | pmc = 1684283 | pmid = 1539595 |via=| vauthors = Inglehearn CF, Lester DH, Bashir R, Atif U, Keen TJ, Sertedaki A, Lindsey J, Jay M, Bird AC, Farrar GJ }}
* {{cite journal |last=|first=| date = May 1992 |year=| title = Ocular findings associated with a rhodopsin gene codon 106 mutation. Glycine-to-arginine change in autosomal dominant retinitis pigmentosa |url=| journal = Archives of Ophthalmology | volume = 110 | issue = 5 | pages = 646–53 | doi = 10.1001/archopht.1992.01080170068026 | pmid = 1580841 |via=| vauthors = Fishman GA, Stone EM, Gilbert LD, Sheffield VC }}
* {{cite journal |last=|first=| date = September 1991 |year=| title = Autosomal dominant retinitis pigmentosa: four new mutations in rhodopsin, one of them in the retinal attachment site |url=| journal = Genomics | volume = 11 | issue = 1 | pages = 199–205 | doi = 10.1016/0888-7543(91)90119-Y | pmid = 1765377 |via=| vauthors = Keen TJ, Inglehearn CF, Lester DH, Bashir R, Jay M, Bird AC, Jay B, Bhattacharya SS }}
* {{cite journal |last=|first=| date = October 1991 |year=| title = Mutation spectrum of the rhodopsin gene among patients with autosomal dominant retinitis pigmentosa |url=| journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 88 | issue = 20 | pages = 9370–4 | doi = 10.1073/pnas.88.20.9370 | pmc = 52716 | pmid = 1833777 |via=| vauthors = Dryja TP, Hahn LB, Cowley GS, McGee TL, Berson EL }}
* {{cite journal |last=|first=| date = October 1991 |year=| title = Pro-347-Arg mutation of the rhodopsin gene in autosomal dominant retinitis pigmentosa |url=| journal = Genomics | volume = 11 | issue = 2 | pages = 468–70 | doi = 10.1016/0888-7543(91)90159-C | pmid = 1840561 |via=| vauthors = Gal A, Artlich A, Ludwig M, Niemeyer G, Olek K, Schwinger E, Schinzel A }}
* {{cite journal |last=|first=| date = August 1991 |year=| title = Rhodopsin mutations in autosomal dominant retinitis pigmentosa |url=| journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 88 | issue = 15 | pages = 6481–5 | doi = 10.1073/pnas.88.15.6481 | pmc = 52109 | pmid = 1862076 |via=| vauthors = Sung CH, Davenport CM, Hennessey JC, Maumenee IH, Jacobson SG, Heckenlively JR, Nowakowski R, Fishman G, Gouras P, Nathans J }}
* {{cite journal |last=|first=| date = September 1991 |year=| title = Retinal function and rhodopsin levels in autosomal dominant retinitis pigmentosa with rhodopsin mutations |url=| journal = American Journal of Ophthalmology | volume = 112 | issue = 3 | pages = 256–71 | doi =  10.1016/s0002-9394(14)76726-1| pmid = 1882937 |via=| vauthors = Jacobson SG, Kemp CM, Sung CH, Nathans J }}
* {{cite journal |last=|first=| date = October 1991 |year=| title = Identification of novel rhodopsin mutations associated with retinitis pigmentosa by GC-clamped denaturing gradient gel electrophoresis |url=| journal = American Journal of Human Genetics | volume = 49 | issue = 4 | pages = 699–706 | doi =  | pmc = 1683182 | pmid = 1897520 |via=| vauthors = Sheffield VC, Fishman GA, Beck JS, Kimura AE, Stone EM }}
{{Refend}}

== External links ==
{{Commons category|Rhodopsins}}
* {{MeshName|Rhodopsin}}
* {{cite web | url = http://webvision.med.utah.edu/ | title = Webvision Home Page: The organization of the retina and visual system |vauthors=Kolb H, Fernandez E, Nelson R, Jones BW | date = 2010-03-01 | format = | work = | publisher = University of Utah | pages = | archiveurl = | archivedate = | quote = | accessdate = }}
* [http://macromoleculeinsights.com/rhodopsin.php The Rhodopsin Protein]
* [http://www.blackwellpublishing.com/matthews/rhodopsin.html Photoisomerization of rhodopsin], animation.
* [http://www.chm.bris.ac.uk/webprojects2003/rogers/998/Rhoeye.htm Rhodopsin and the eye], summary with pictures.
* {{UMichOPM|families|superfamily|6}} - Calculated spatial positions of rhodopsin-like proteins in membrane

{{PDB Gallery|geneid=6010}}
{{G protein-coupled receptors}}
{{Eye proteins}}
{{Use dmy dates|date=April 2017}}

[[Category:G protein coupled receptors]]
[[Category:Sensory receptors]]
[[Category:Biological pigments]]
[[Category:Eye]]
[[Category:Genes on human chromosome 3]]