Figure 6.

Characterization of the quintuple TSLMF mutant. a, Addition of 3 μm PNU to the extracellular solution surrounding a cell-attached patch containing the TSLMF mutant, activated by 100 μm ACh, shows no PNU-induced change in single-channel activity. b, Whole-cell currents elicited by separate applications of 100 μm ACh for a single HEK 293 cell expressing the TSLMF mutant before (left) and after (right) a 60 s incubation with 3 μm PNU. c, PNU dose–response relationships for wild-type (black circles) and TSLMF mutant α7 (white triangles) determined from single-channel recordings (n = 2 or 3 recordings for each data point; see Materials and Methods). d, Ability of PNU to allosterically modulate agonist affinity. ACh binding was measured by its competition against the initial rate of α-bungarotoxin binding for both wild-type (circles) and TSLMF mutant (triangles) receptors in the presence (black circles, white upward triangles) and absence (gray circles and downward triangles) of 3 μm PNU (n = 3 for each data point). Error bars in c and d represent ± standard deviation of the means.