Extended Data Table 3 Effects of various mutations on δ-OR radioligand binding parameters
- a, For these experiments 3H-naltrindole saturation and DADLE competition assays using 3H-naltrindole in the absence of sodium chloride were performed. Results are presented as average ± s.e.m. from two or more separate experiments, each in triplicate. Binding curves were fit to a one-site model. The same data were also fit to a two-site model and the results are shown in Extended Data Table 3b. NA, no activity; these receptor mutants expressed receptor which did not bind 3H-naltrindole. b, DADLE binding against 3H-naltrindole in the absence of sodium chloride fit to a two-site model. Results are presented as average ± s.e.m. from three or four assays. High-affinity fraction values were taken directly from curve-fitting. High and low IC50 values and their corresponding 95% confidence intervals (C.I.) were taken from curve-fitting and converted to corresponding high and low affinity (pKi) and 95% C.I. values using the Cheng–Prusoff equation. Note that D95A reduced high DADLE-binding affinity, but did not significantly reduce the high-affinity fraction. D95N reduced the high-affinity fraction, but did not reduce DADLE high affinity. N131A or N131V increased DADLE high affinity. DADLE low affinity remained unchanged in all mutants. *P < 0.0001, **P < 0.05, as compared with wild-type δ-OR using one-way ANOVA.
