ACh and NS9283 sensitivity of receptors from α4^VFL subunit containing concatenated pentameric constructs with short first linkers. X. laevis oocytes were subjected to two-electrode voltage-clamp electrophysiology. Electrophysiological data were evaluated as described in Materials and methods; also see Fig. 1. (A and B) ACh (A) and NS9283 (B) CRRs were obtained from oocytes injected with the indicated pentameric constructs. Data from n = 9–15 experiments are depicted as means ± SEM as a function of the ACh or NS9283 concentration, and regression results are presented in Table 2. Data for the β-3a-α-β-α-α^VFL construct are from Fig. 7, and data for wild-type receptors from monomeric subunits in Fig. 1 are indicated as dashed lines. The preferred expression orientation of each pentamer is indicated for the NS9283 data. (C) Representative traces illustrating NS9283 responses at oocytes injected with β-3a-α^VFL-β-α-α or β-3a-α^VFL-α-β-α. Bars above the traces indicate the 30-s application time and concentrations of applied compounds.