Fig. 2.
Concentration-response properties of human β3 homomeric receptors. The figure shows propofol (A) and pentobarbital (B) concentration-response curves for wild-type and mutant receptors. The data points show normalized responses (mean ± S.E.M.) from at least four cells at each condition. Current responses were normalized to the response to the highest concentration of agonist used in the experiment. The curves show predictions of eq. 1 generated with the overall mean EC50 values from Table 1. In (A), the maximal fitted response and nH were 1.05 ± 0.03 and 1.6 ± 0.2 (wild type), 1.07 ± 0.02 and 1.7 ± 0.1 (H267W), 1.1 ± 0 and 1.6 ± 0.1 (L268W), and 0.99 ± 0.04 and 0.98 ± 0.16 (Y143W). Receptors containing the T266W, Q224W, or F221W mutations did not reliably produce responses in the presence of propofol. In (B), the maximal fitted response and nH were 1.03 ± 0.03 and 1.6 ± 0.04 (wild type), 1.14 ± 0.03 and 1.8 ± 0.3 (H267W), 1.0 ± 0.03 and 1.8 ± 0.2 (L268W), 1.05 ± 0.04 and 1.1 ± 0.04 (Y143W), 1.03 ± 0.03 and 0.9 ± 0.2 (T266W), and 0.98 ± 0.02 and 2.9 ± 0.04 (Q224W).