|
Rhodopsin consists of the protein opsin linked to 11-cis retinal a prosthetic group. Retinal is the light absorbing pigment molecule and is a derivative of vitamin A.
The protein Rhodopsin contains the protonated retinal-Schiff's base complex which naturally lies in the inter-membrane pocket formed by the seven trans-membrane a -helical receptors. There are many flat discs of rhodopsin within the outer segment of a rod cell which upon light detection undergo a photo-isomeric change from Rhodopsin (11- cis ) to all- trans retinal.
Rhodopsin, also known as visual purple, is a vertebrate photoreceptor protein.
Rhodopsin is a protein in the membrane of the rod photoreceptor cell in the retina of the eye. It catalyses the only light sensitive step in vision.
Rhodopsin is the visual pigment for dim light vision and the probably best studied GPCR. Up to now, rhodopsin is the only receptor of this family, of which a crystal structure of the inactive state is available. Rhodopsin is a transmembrane protein consisting of 7 membrane-spanning helices, that are interconnected by extracellular and cytoplasmic loops. As a chromophore, it has covalently bound in its inactive dark state 11- cis retinal , which isomerizes after photon absorption to an all- trans geometry.
Photons of light focus upon the retina causing the twisting (isomerization) at a double bond of two carbon atoms within the rhodopsin molecule. The signals are then transmitted to the brain for interpretation.
|
