Fig. 8.

Functional characterization of mutations on the TK putative phosphorylation site in the α4 subunit with nicotine used as an agonist. Voltage-clamp recordings were used to determine the macroscopic response to several nicotine concentrations of mutations of TK putative sites and wild-type α4β2 nAChRs expressed in Xenopus laevis oocytes. (A) Family of nicotine-induced macroscopic currents for mutation α4Y576Aβ2 and the wild-type α4β2 nAChR. Calibration bars are shown for all family of currents, horizontal bars indicate time (5 s) and vertical bars indicate the inward current (500 nA). (B) Dose-response relationships obtained by voltage-clamp experiments with nicotine used as an agonist. Nicotine dose-response curves were determined using seven nicotine concentrations (0.1, 1, 3, 10, 30, 100, and 300 μM). The responses were normalized to the maximum response (I/Imax). (C) Comparison of the nicotine-induced macroscopic peak currents, shown in nA (n=6-17) (*p<0.05).