FIGURE 2.

GABA sensitivities of mutant receptors. (A) Representative traces of GABA-induced currents for the wild-type GABA receptor and the three different mutations examined in this study. In this case, all subunits carry the indicated mutation; serine (S), valine (V), or tyrosine (Y). (B) The GABA dose-response relationship for the wild-type receptor (open circles), as well as the receptors where all five subunits were mutated to serine (solid circles), valine (squares), or tyrosine (diamonds). The continuous lines are fits of the Hill equation (Eq. 1) to the dose-response relationships of the peak current and yielded EC₅₀ values of 64.6 ± 2.2, 81.3 ± 7.5, 81.3 ± 6.9, and 88.7 ± 4.7 μM for wild-type, T6′S, T6′V, and T6′Y, respectively. This pore mutation did not significantly alter the sensitivity of the receptor to GABA.