Rhodopsin
Rhodopsin is the photoreceptor protein in rod cells of vertebrate retina [1]. It is also known as opsin 2.
Rhodopsin is a member of the GPCR family, which is coupled to the G-protein, transducin. Rhodopsin, unlike many other GPCRs is activated by a photon of light not by the binding of a ligand. Infact, the ligand (11-cis retinal) is already bound in its inactive state. The photon causes a conformational change in the GPCR which causes activation of the transducin, whose α subunit, then activates cyclic GMP phosphodiesterase [2].
"Retinitis Pigmentosa" is an inherited disease that causes blindness or stationary night blindness, by degenerating retina cells. It might be an autosomal dominant or recessive and X-linked recessive disease, at which a mutation in the gene encoding rodopsin. Vitamin A improves the condition.[3]
References
- ↑ Hargrave P.A., McDowell J.H.(1992) Rhodopsin and phototransduction: a model system for G protein-linked receptors. The FASEB Journal, 6(6), 2323-2331
- ↑ Alberts.B, Johnson.A, Lewis.J, Raff.M, Roberts.K, Walter.P, 2008, Molecular Biology of the Cell, 5th Edition, New York, Garland Science
- ↑ Kelly, J, (2011) Retinitis Pigmentosa 4; RP4,OMIM.org (lasst isited 20/11/2011)