11cRAL binds to opsin to form 11c-retinyl:RHO

Stable Identifier
Homo sapiens
11-cis-retinal binds to rhodopsin
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Human opsin-2 is a G-protein coupled photoreceptor found in the disc membranes of rod outer segments (ROS) (Nathans & Hogness 1984). It is an integral membrane protein and covalently binds the chromophore 11-cis-retinal (11cRAL) to form rhodopsin (RHO). Binding occurs via a protonated Schiff base linkage at Lys-296 (Fan et al. 2002) with Glu-113 at helix 3 serving as the counterion of the protonated Schiff base (Han et al. 1993). The resultant 11-cis-retinyl (11c-retinyl) group attached to lysine is completely embedded within the RHO structure. Opsins found in cone outer segments which bind 11cRAL are described in the cone visual cycle. Unlike other GPCRs in which direct ligand binding activates the receptor, rhodopsin is in an inactive state when bound to 11c-retinyl (which acts as an inverse agonist).

Literature References
PubMed ID Title Journal Year
6589631 Isolation and nucleotide sequence of the gene encoding human rhodopsin.

Nathans, J, Hogness, DS

Proc Natl Acad Sci U S A 1984
8105993 Localization of the retinal protonated Schiff base counterion in rhodopsin

Han, M, DeDecker, BS, Smith, SO

Biophys. J. 1993
12177057 Rhodopsin with 11-cis-locked chromophore is capable of forming an active state photoproduct

Fan, G, Siebert, F, Sheves, M, Vogel, R

J. Biol. Chem. 2002
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