Figure 3.

The concentration–response properties for wild-type and α1L127Cβ2γ2L mutant receptors. Current (open squares) and fluorescence change (filled squares) concentration–response curves are shown for the α1L127Cβ2γ2L receptor labelled with Alexa Fluor 546 C5 maleimide. The curves were fitted to the Hill equation yielding an EC₅₀ of 117 ± 41 µM, n_H= 0.5 ± 0.1 and maximal response = 1.2 ± 0.1, and an EC₅₀ of 173 ± 60 µM, n_H= 0.8 ± 0.2 and maximal response = 1.2 ± 0.1 for current and fluorescence change respectively. For comparison, the concentration–response curve for currents from wild-type α1β2γ2L receptors (open circles) had an EC₅₀ of 4.3 ± 0.3 µM, and a Hill coefficient of 1.5 ± 0.1. The oocytes were clamped at −60 mV. Each data point shows mean ± SEM from 3–9 oocytes.