GABA potency at GABA_ARs from concatenated α-xa-β dimer constructs. X. laevis oocytes were subjected to two-electrode voltage-clamp electrophysiology and electrophysiological data were evaluated as described in the Materials and methods; also see Fig. 1. cRNA for α-xa-β constructs were injected alone (A, B, C, and J), coinjected with a monomeric β2 subunit in a 1:1 ratio (D, E, F, J, K, and L), or coinjected with a monomeric γ2 subunit in a 1:1 ratio (G, H, I, and J). (A, D, G, and J) GABA_max-evoked peak-current amplitudes are depicted as means ± SEM for receptors from the indicated cRNA mixtures. A GABA concentration of 316 µM was used as GABA_max for all construct combinations with the exception of α-10-β+γ2, for which a concentration of 3,160 µM was used. Data were obtained from n = 7–24 experiments and calculated averages are presented in Table 1. (B, E, H, and K) GABA CRRs are depicted as means ± SD for receptors from the indicated cRNA mixtures. Data were obtained from n = 7–24 experiments and regression results are presented in Table 1. (C, F, I, and L) Representative traces illustrating GABA CRRs at receptors from the indicated cRNA mixtures. Bars above the traces designate the 30-s application time and concentrations of applied GABA are indicated for each trace.