Binding specificity of retinal analogs to photoactivated visual pigments suggest mechanism for fine-tuning GPCR-ligand interactions
Related Experiment Video
Updated: May 2, 2026

Author Spotlight: Unraveling Vitamin A Transport Mechanisms — Linking Liver Receptors to Vision Health Through RBPR2 and RBP4 Interactions
Published on: October 4, 2024
Sundaramoorthy Srinivasan1, Eva Ramon1, Arnau Cordomí2
1Chemical Engineering Department, Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain.
Abstract:
11-cis-retinal acts as an inverse agonist stabilizing the inactive conformation of visual pigments, and upon photoactivation, it isomerizes to all-trans-retinal, initiating signal transduction. We have analyzed opsin regeneration with retinal analogs for rhodopsin and red cone opsin. We find differential binding of the analogs to the receptors after photobleaching and a dependence of the binding kinetics on the oligomerization state of the protein. The results outline the sensitivity of retinal entry to the binding pocket of visual receptors to the specific conformation adopted by the receptor and by the molecular architecture defined by specific amino acids in the binding pocket and the retinal entry site, as well as the topology of the retinal analog. Overall, our findings highlight the specificity of the ligand-opsin interactions, a feature that can be shared by other G-protein-coupled receptors.
Related Concept Videos
GPCR Desensitization
Photoreceptors and Visual Pathways
G-Protein Gated Ion Channels
Sensory...
GPCRs Regulate Adenylyl Cylase Activity
Transducer Mechanism: G Protein–Coupled Receptors
GPCRs are also called heptahelical,...
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...

