Figure 1.
LGC-53 is an atypical anion channel. A, Responses of an oocyte expressing LGC-53 to increasing concentrations of DA. B, Concentration–response curve of peak currents at the indicated DA concentrations, normalized to responses at 100 μm DA (n = 6). The solid line is a fit to the Hill equation, which estimated an EC50 of 6.4 μm and a Hill slope of 1.8. C, N2a cells were transfected with LGC-53 DNA and challenged with DA (30 μm) in cells filled with the indicated whole-cell pipette solutions. D, Current–voltage curves compare anion permeability for LGC-53 expressed in N2a cells (30 μm DA; n = 4 for each pipette solution) and GABAA receptors in hippocampal neurons (10 μm GABA; n = 4 for each solution) in culture. E, F, Recovery from desensitization is rapid. HEK 293T cells transfected with LGC-53 were challenged with 30 μm DA, which evoked biexponential macroscopic desensitization, followed by saline wash for 500 ms. In successive sweeps, the interval was increased as indicated, and the ratio of test response to initial, conditioning response is plotted for each interval (n = 6). G, H, Steady-state desensitization properties of LGC-53 in HEK 293T cells. Significant desensitization with preapplication time of 10 s was not observed at concentrations below 3 μm (n = 5). MeS, methanesulfonate.