Figure 2. Functional characterization of... | Rockefeller University Press

Figure 2.

$Figure 2. Functional characterization of the ELIC-GLIC chimera. (A) A schematic representation of the chimera based on GLIC (PDB accession no. 4HFI) and ELIC (PDB accession no. 3RQU) structures, and the sequence alignment highlighting the region where the ELIC-ECD was fused to the GLIC-TMD (top). Agonist-induced (25 mM 3-AP) 13-min current response in oocytes measured by two-electrode voltage clamp (bottom). Inset shows (B) current traces for the chimera 9′Ala mutant in response to activation by acid (pH 5.0), agonist (25 mM GABA), and a combination of both. The plot shows peak response for the three conditions. The error bars denote standard deviation (n = 3). (C) Dose–response curves for the 9′Ala mutant (solid line) in the presence of 3-AP (dashed line, compared with ELIC) or acid (dashed line, comparison with GLIC). Currents are expressed as a fraction of the maximal response. The error bars denote standard deviation (n > 5). The EC50 (3-AP) and pH50 values are 32.8 ± 9.1 mM and 4.22 ± 0.11, and the corresponding Hill coefficients are 1.1 ± 0.2 and 9.1 ± 2.1, respectively. The EC50 (3-AP) and Hill coefficient for WT ELIC are 10.02 ± 0.05 mM and 2.5 ± 0.3. The EC50 (pH) and Hill coefficient for WT GLIC are 4.89 ± 0.06 mM and 2.0 ± 0.1. The error bars for WT denote standard deviation (n > 3).$

Functional characterization of the ELIC-GLIC chimera. (A) A schematic representation of the chimera based on GLIC (PDB accession no. 4HFI) and ELIC (PDB accession no. 3RQU) structures, and the sequence alignment highlighting the region where the ELIC-ECD was fused to the GLIC-TMD (top). Agonist-induced (25 mM 3-AP) 13-min current response in oocytes measured by two-electrode voltage clamp (bottom). Inset shows (B) current traces for the chimera 9′Ala mutant in response to activation by acid (pH 5.0), agonist (25 mM GABA), and a combination of both. The plot shows peak response for the three conditions. The error bars denote standard deviation (n = 3). (C) Dose–response curves for the 9′Ala mutant (solid line) in the presence of 3-AP (dashed line, compared with ELIC) or acid (dashed line, comparison with GLIC). Currents are expressed as a fraction of the maximal response. The error bars denote standard deviation (n > 5). The EC₅₀ (3-AP) and pH₅₀ values are 32.8 ± 9.1 mM and 4.22 ± 0.11, and the corresponding Hill coefficients are 1.1 ± 0.2 and 9.1 ± 2.1, respectively. The EC₅₀ (3-AP) and Hill coefficient for WT ELIC are 10.02 ± 0.05 mM and 2.5 ± 0.3. The EC₅₀ (pH) and Hill coefficient for WT GLIC are 4.89 ± 0.06 mM and 2.0 ± 0.1. The error bars for WT denote standard deviation (n > 3).