Simultaneously fitting binding data from several different concentrations of α4β2 nAChR identifies low-affinity specific binding. A. The one site modeltotal and two sites modeltotal with [3H]EBmax = 100 nM were fitted to noisy binding data with R1T = 0.065, 0.13, and 0.39 nM and α = 0. SD for noise at the R1T values was 0.002, 0.004, and 0.012, respectively (maximum S/N ratio≃36). The two sites modeltotal shows a significantly better fit (p = 4 × 10-7). B. The y-axis shows p values for comparisons of one site modeltotal and two sites modeltotal from various [3H]EBmax values. The fitted data sets are analogous to the data sets shown in A; p-values from 5 data sets appear at each x-coordinate. Solid lines connect averages of log(p) values. The CIs of estimates of Kd1 (9.2-18.5 pM; mean = 13.0 pM) and Kd2 (1.0-1400 nM; mean = 38 nM) and R2T (0.015-0.66; mean = 0.34) (n = 5 for each CI) include true values.
Person and Wells BMC Biophysics 2011 4:19 doi:10.1186/2046-1682-4-19