Plot of the fraction of the agonist-binding domain of the GluA2 subunit exhibiting FRET efficiencies higher than 0.76 versus normalized mean currents obtained with the corresponding agonists activating the full-length receptors. The data for the glutamate bound and apo form of wild type, as well as glutamate-bound form of T686S mutant, were obtained from Landes et al. (30). ClW, chlorowilladiine; NO2W, nitrowillardiine; IW, iodowillardiine.