Figure 8.

Determination of radioligand and FPT kinetic binding parameters at 5-HT_1ARs, 5-HT_2CRs and 5-HT₇Rs. (a–c) Association kinetics of three concentrations of radioligand (10×, 5×, and 1× K_d) at (a) 5-HT_1ARs, (b) 5-HT_2CRs, and (c) 5-HT₇Rs. (d–f) Plot of the observed association rate versus radioligand concentration yields a linear relationship for 5-HT_1ARs, 5-HT_2CRs, and 5-HT₇Rs, indicative of ligand binding to a single site. (g–i) Competition kinetics of varying concentrations of unlabeled FPT in the presence of 5–10 nM radioligand at 5-HT_1ARs, 5-HT_2CRs, and 5-HT₇Rs. Data are organized in columns by receptor, and in rows by assay format. Association curves were derived from 3–5 independent experiments, normalized where the specific binding of radioligand at the latest time point is 100%, and binding at time 0 is fixed to 0%. Data reporting the k_obs (k_obs = (k_on × [radioligand]) + k_off) are presented in singlet form from an individual association binding experiment.