FIGURE 7.

The relationship between the effect of mutations on binding and function of the different ligands. The effect of mutations on binding affinity (ΔpK_i) is compared with their effect on function (ΔpIC₅₀) for the tested ligands salvinorin A, 1xx, dynorphin A, and U-69593. The middle diagonal line indicates identical effects on binding and function. The outside lines are 1 log unit above and below this “line of identical effect.” Gray points indicate mutations that affected function more than binding. Black points outside the 1 log difference line belong to the low expressing mutations L212A and I135A.