FIGURE 1.

Effects on the single channel slope conductance of α1 homomeric GlyR of a charge reversal mutation of the extracellular domain conductance determinant in loop 5. A and C are examples of inward (A) and outward (C) currents (low-pass filtered at 1 kHz) recorded from HEK cells in the cell-attached configuration in the presence of 0.2 mm Gly. Imposed holding potentials are as indicated. For inward currents only (recorded in a Na⁺-based external solution) the true transmembrane potential will depend also on the cell resting membrane potential. Outward currents were recorded in K⁺-based external solution, which effectively abolishes the cell resting potential. The baseline is indicated by a dashed line for each trace. B and D are current-voltage relationships for wild type (continuous line, Δ) and mutant receptors (dashed line, ●), for inward and outward currents, respectively. E, alignment of loop 5 of Torpedo α1, GABA_A, and Gly subunits. The conserved charged residues are bold and highlighted in gray. Charge reversal mutations at a position homologous to Asp-97 of the α1 Torpedo (6) replace Lys with Glu and are indicated throughout by the superscript KE.