Single-molecule Förster resonance energy transfer (smFRET) can be used to probe the structural dynamics underlying the functional complexity of G protein-coupled receptors (GPCRs), however, the approach is limited to specific timescales. Here, the authors use smFRET with anti-Brownian electrokinetic (ABEL) trapping to extend the observation time of untethered A2A adenosine receptors (A2AAR) embedded in lipid nanodiscs from milliseconds to seconds, characterizing conformational heterogeneity in both apo and ligand-bound A2AAR and updating previous estimates of dwell times for long-lived receptor states.
- Ivan Maslov
- Valentin Borshchevskiy
- Thomas Gensch
