Figure 6. Calcium block and permeation are affected by N619K mutation.

A and B. Example traces of responses from WT/;2 (grey in Na⁺, black in Ca²⁺) and N619K/γ2 (dark cyan in Na⁺, green in Ca²⁺) at various membrane potentials (in 10 mV increments) in absence of spermine. Receptors were activated with 10mM L-glutamate. The external solutions; Na⁺ = 150mM Na⁺ recording solution (patch # 190117p5 for WT/γ2, patch # 221124p2 for N619K/γ2), and Ca²⁺ = 108 mM Ca²⁺ recording solution (patch # 190117p5 for WT/γ2 and # 221124p2 for N619K/γ2). C. Current-voltage (I-V) plots of mutant N619K/γ2 receptors (n=10) in external 150 mM Na⁺ (blue circles) or 108 mM Ca²⁺ (green circles). In dashed black line it is shown IV plot of WT/γ2 receptors (n=8) in 108 mM Ca²⁺ (dotted line). Data are presented as mean values ± SEM. D. (Top) Scatter plot comparing the reversal potential in 108 mM Ca²⁺ from WT/γ2 and N619K/γ2. Grey (WT/γ2) and cyan (N619K/γ2) squares indicate average with SEM (Vrev = 34.1 ± 0.8 mV for WT/γ2, n=8; Vrev = −15.4 ± 2.3 mV N619K/γ2, n=10; unpaired two-sided t-test with Welch correction, p-value < 0.001). D. (Bottom) Comparison of the relative divalent permeabilities (P_Ca2+/P_Na+) of WT/γ2 and mutant N619K/γ2 receptors (P_Ca2+/P_Na+ =5.28 ± 0.21 for WT/γ2, n=8; P_Ca2+/P_Na+ = 0.32 ± 0.04 for N619K/γ2, n=10) unpaired two-sided t-test with Welch correction, p-value < 0.001). (Also see in Supplementary Table 8)