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. 2012 May 18;287(30):25520–25529. doi: 10.1074/jbc.M112.374397

FIGURE 4.

FIGURE 4.

Electrophysiological characterization of heterologous NR1/NR2B-ΔATD-R67 receptors in Xenopus oocytes. A, (i) shown is a model of NR2B subunit consisting of ATD, agonist binding domain (S1S2), transmembrane domains, and the carboxyl terminus. Glutamate binds to the S1S2 domain, whereas critical amino acid residues affecting ifenprodil inhibition reside in the ATD. (ii) shown is a schematic representation of the full-length NR2B (NR2BWT) (upper panel) and truncated NR2B (deletion of Gln29–Arg67) (NR2B-ΔATD-R67) (lower panel) constructs. SP represents signal peptide, and M1, M3, and M4 represent transmembrane domain, whereas M2 represents the reentrant loop. B, the mean normalized concentration-response curve for glutamate in saturating concentrations of glycine (100 μm; pH 7.3) was obtained from oocytes expressing NR1/NR2BWT (open circles and solid line; n = 7) and NR1/NR2B-ΔATD-R67 (open triangle and dotted line; n = 6). Glutamate EC50 for NR1/NR2BWT and NR1/NR2B-ΔATD-R67 are 0.85 ± 0.12 and 0.94 ± 0.16 μm, respectively. p > 0.05, two-tailed unpaired t test. C, shown is a mean normalized concentration-response curve for glycine in saturating concentrations of glutamate (100 μm; pH 7.3) obtained from oocytes expressing NR1/NR2BWT (open circles and solid line; n = 6) and NR1/NR2B-ΔATD-R67 (open triangle and dotted line; n = 7). Glycine EC50 values for NR1/NR2BWT and NR1/NR2B-ΔATD-R67 are 0.28 ± 0.02 and 1.37 ± 0.19 μm, respectively, and are statistically significantly different. p < 0.001, two-tailed unpaired t test. D, shown is a mean normalized concentration-response curve for ifenprodil inhibition in saturating concentrations of glutamate and glycine (100 μm each; pH 7.3) obtained from oocytes expressing NR1/NR2BWT (open circles and solid line; n = 12) and NR1/NR2B-ΔATD-R67 (open triangle and dotted line; n = 4). Ifenprodil IC50 values for NR1/NR2BWT and NR2B-ΔATD-R67 are 0.35 ± 0.10 and 24.09. ± 18.15 μm, respectively, and are statistically significantly different. p < 0.05, two-tailed unpaired t test.