Figure 1.

Zn²⁺ inhibition is pH dependent for NR2A but not NR2B-containing receptors. (A) Inhibition of NR1-1a(D669N)/NR2A receptors by 1 μM added Zn²⁺ at two indicated pHs from the same oocyte. (B) Inhibition of NR1-1a(D669N)/NR2B receptor by 15 μM added Zn²⁺ at two indicated pHs from the same oocyte. All control currents for NR2A-containing receptors were recorded in the presence of 10 μM EDTA. The NR1(D669N) mutant was used to shift the pH sensitivity to a range where formation of Zn²⁺ hydroxide complex is negligible at alkaline pHs. (C) Plot of the degree of Zn²⁺ inhibition at various pH values for NR1-1a(D669N) containing NR2A (−20 to −40 mV) or NR2B (−15 to −30 mV) receptors. (D) Wild-type NR1-1a receptors containing NR2A or NR2B subunit in the presence of 3 μM and 15 μM added Zn²⁺, respectively, confirm the observation in C. ○, Outward responses recorded at +20 mV for NR1-1a/NR2B. All error bars are SEM. Numbers in parentheses are the number of oocytes.