A constitutively activating mutation alters the dynamics and energetics of a key conformational change in a ligand-free G protein-coupled receptor

Background: Constitutively active mutations (CAMs) affect the dynamics of G protein-coupled receptors (GPCRs), through undefined mechanisms. Results: Site-directed fluorescence labeling (SDFL) studies find a CAM (M257Y) alters the dynamics of the GPCR ligand-free opsin. Conclusion: The M257Y CAM alters the dynamics of the conversion between active and inactive opsin conformations. Significance: SDFL can be used to gain insights into how CAMs affect the dynamics of G protein-coupled receptors.