Vertebrate rhodopsin consists of the apoprotein opsin and the chromophore 11-cis-retinal covalently linked via a protonated Schiff base. Upon photoisomerization of the chromophore to all-trans-retinal, the retinylidene linkage hydrolyzes, and all-trans-retinal dissociates from opsin. The pigment is eventually restored by recombining with enzymatically produced 11-cis-retinal. All-trans-retinal ...

Rhodopsin is the prototypical G protein-coupled receptor, responsible for detection of dim light in vision. Upon absorption of a photon, rhodopsin undergoes structural changes, characterised by distinct photointermediates. Currently, only the ground-state structure has been described. We have determined a density map of a photostationary state highly enriched in metarhodopsin I, to a resolution...

The origin of spontaneous quantum bumps has been examined in the ultraviolet photoreceptors of Limulus median eye. These cells have a rhodopsin with a lambda max at 360 nm and a stable photoproduct, metarhodopsin, with a lambda max at 470 nm. The steady state rate of spontaneous quantum bumps was found to be higher when the metarhodopsin concentration was high than when the rhodopsin concentrat...

Absorbance spectra were recorded at various times after photolysis of hypotonically washed membrane suspensions of human and bovine rhodopsin (pH 7 or 8, T = 20 or 37 degrees C). Global data analysis showed that at 20 degrees C, metarhodopsin III formation was the only process occurring from 1 to 30 min following photolysis. At pH 8, a significant amount of human metarhodopsin I was present bef...

The visual pigment rhodopsin is unique among the G protein-coupled receptors in having an 11-cis retinal chromophore covalently bound to the protein through a protonated Schiff base linkage. The chromophore locks the visual receptor in an inactive conformation through specific steric and electrostatic interactions. This efficient inverse agonist is rapidly converted to an agonist, the unprotona...

Rhodopsin is the best-understood member of the large G protein-coupled receptor (GPCR) superfamily. The G-protein amplification cascade is triggered by poorly understood light-induced conformational changes in rhodopsin that are homologous to changes caused by agonists in other GPCRs. We have applied the "antibody imprint" method to light-activated rhodopsin in native membranes by using nine mo...

A prevalent model for the function of rhodopsin centers on the metarhodopsin I (MI) to metarhodopsin II (MII) conformational transition as the triggering event for the visual process. Flash photolysis techniques enable one to determine the [MII]/[MI] ratio for rhodopsin in various recombinant membranes, and thus investigate the roles of the phospholipid head groups and the lipid acyl chains sys...