Beyond spectral tuning: human cone visual pigments adopt different transient conformations for chromophore regeneration.

ABSTRACT: Human red and green visual pigments are seven transmembrane receptors of cone photoreceptor cells of the retina that mediate color vision. These pigments share a very high degree of homology and have been assumed to feature analogous structural and functional properties. We report on a different regeneration mechanism among red and green cone opsins with retinal analogs using UV-Vis/fluorescence spectroscopic analyses, molecular modeling and site-directed mutagenesis. We find that photoactivated green cone opsin adopts a transient conformation which regenerates via an unprotonated Schiff base linkage with its natural chromophore, whereas red cone opsin forms a typical protonated Schiff base. The chromophore regeneration kinetics is consistent with a secondary retinal uptake by the cone pig

SUBMITTER: Srinivasan S 

PROVIDER: S-EPMC11108329 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature