Complex binding pathways determine the regeneration of mammalian green cone opsin with a locked retinal analogue.

Phototransduction is initiated when the absorption of light converts the 11--retinal chromophore to its all- configuration in both rod and cone vertebrate photoreceptors. To sustain vision, 11--retinal is continuously regenerated from its all- conformation through a series of enzymatic steps comprising the "visual or retinoid" cycle. Abnormalities in this cycle can compromise vision because of the diminished supply of 11--retinal and the accumulation of toxic, constitutively active opsin.