Human Blue Cone Opsin Regeneration Involves Secondary Retinal Binding with Analog Specificity

Sundaramoorthy Srinivasan, Miguel A. Fernández-Sampedro, Margarita Morillo, Eva Ramon, Mireia Jiménez-Rosés, Arnau Cordomí, Pere Garriga

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Human color vision is mediated by the red, green, and blue cone visual pigments. Cone opsins are G-protein-coupled receptors consisting of an opsin apoprotein covalently linked to the 11-cis-retinal chromophore. All visual pigments share a common evolutionary origin, and red and green cone opsins exhibit a higher homology, whereas blue cone opsin shows more resemblance to the dim light receptor rhodopsin. Here we show that chromophore regeneration in photoactivated blue cone opsin exhibits intermediate transient conformations and a secondary retinoid binding event with slower binding kinetics. We also detected a fine-tuning of the conformational change in the photoactivated blue cone opsin binding site that alters the retinal isomer binding specificity. Furthermore, the molecular models of active and inactive blue cone opsins show specific molecular interactions in the retinal binding site that are not present in other opsins. These findings highlight the differential conformational versatility of human cone opsin pigments in the chromophore regeneration process, particularly compared to rhodopsin, and point to relevant functional, unexpected roles other than spectral tuning for the cone visual pigments.

Original languageEnglish
Pages (from-to)1285-1294
Number of pages10
JournalBiophysical Journal
Issue number6
StatePublished - 27 Mar 2018


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