Fig. 2.

Properties of KCNQ2/3/5 heteromeric channels. (A) Left, representative recordings from cells expressing either KCNQ2/5-tandem subunits or KCNQ2/5-tandem subunits along with KCNQ3. Right, summary graphs comparing the conductance-to-voltage relationship of KCNQ2/5-tandem channels (the curve fit from Fig. 1C is illustrated for comparison), KCNQ3 channels (V_0.5 = −21.7 ± 3.2 mV, n = 11), and KCNQ2/5-tandem/KCNQ3 channels (V_0.5 = −14.4 ± 1.7 mV, n = 18). Note that coexpression of KCNQ2/5-tandem subunits with KCNQ3 led to a current-to-voltage relationship similar to one obtained for KCNQ2/5-tandem channels. Data are displayed as mean ± SEM. Inset, summary graph comparing KCNQ3 to KCNQ2/5-tandem/KCNQ3 current densities. Significance was determined using the Mann–Whitney U test (**P = 0.0063). (B) Left, representative recordings from cells expressing either KCNQ2/5-tandem subunits or KCNQ2/5-tandem subunits with KCNQ3 in the presence or absence of 10 µM ICA27243. Right, summary graph showing that ICA27243 leads to a smaller shift in the V_0.5 of KCNQ2/5-tandem/KCNQ3 (n = 5) channels compared to KCNQ2/5-tandem channels (n = 6). Statistical significance was determined using the Mann–Whitney U test (*P = 0.036). For illustration purposes, we also show the effect of 10 µM ICA27243 to unlinked KCNQ2 channels (n = 6). (C) Representative traces from HEK293T cells expressing either KCNQ3^R230C subunits or KCNQ2/5-tandem and KCNQ3^R230C subunits. Right, summary graph showing that coexpression of KCNQ2/5-tandem subunits with KCNQ3^R230C leads to a right shifted conductance-to-voltage relationship (KCNQ3^R230C V_0.5 was not determined as KCNQ3^R230C channels were constitutive open and could not be fitted with a Boltzmann function, n = 4; KCNQ2/5-tandem/KCNQ3^R230C, V_0.5 = −85 ± 5.8 mV, n = 6). Data are displayed as mean ± SEM.