TABLE 2

CIQ, glutamate, and glycine EC₅₀ values for GluN1/GluN2D point mutants

EC₅₀ values were determined from two-electrode voltage-clamp recordings of Xenopus laevis oocytes expressing the indicated GluN1/GluN2D receptor. For CIQ EC₅₀ determination, receptors were activated by 100 μM glutamate and 30 μM glycine at −40 mV; 5 mM 2-(hydroxypropyl)-β-cyclodextrin was present in all solutions. For glutamate EC₅₀ measurements, glycine was 30 μM. For glycine EC₅₀ measurements, glutamate was 100 μM. Data are from 4–36 oocytes.

Mutant	Region	CIQ EC₅₀	100 μM CIQ Response	Glutamate EC₅₀	Glycine EC₅₀
		µM	% glu/gly	μM	μM
GluN2D	–	9.3 ± 0.3	253 ± 5	0.82 ± 0.07	0.14 ± 0.02
2D(F574A)	Pre-M1	13.0 ± 1.5^*	150 ± 1	0.057 ± 0.003^*	0.060 ± 0.001^*
2D(L575A)	Pre-M1	38 ± 18	53 ± 4	0.24 ± 0.03^*	0.15 ± 0.02
2D(E576A)	Pre-M1	10.7 ± 0.4	321 ± 12	0.178 ± 0.009^*	0.106 ± 0.002
2D(P577A)	Pre-M1	7.2 ± 0.6^*	127 ± 2	0.398 ± 0.014	0.147 ± 0.002
2D(Y578A)	Pre-M1	4.5 ± 0.4^*	320 ± 30	0.0027 ± 0.0002^{^a}^*	0.0011 ± 0.0001^{^a}^*
2D(V582A)	M1	6.6 ± 0.6^*	143 ± 3	0.17 ± 0.01^*	0.04 ± 0.01^*
2D(V584A)	M1	8.7 ± 0.7	311 ± 12	0.78 ± 0.04	0.14 ± 0.02
2D(M586A)	M1	15.3 ± 1.1^*	510 ± 40	1.90 ± 0.12^*	0.26 ± 0.01^*
2D(F587A)	M1	NE	86 ± 3	0.80 ± 0.05	0.25 ± 0.02^*
2D(V588A)	M1	11.3 ± 1.2	123 ± 3	0.93 ± 0.09	0.12 ± 0.02
2D(L591A)	M1	34.6 ± 5.9^*	218 ± 9	0.99 ± 0.06	0.18 ± 0.01
2D(T592A)	M1	32.5 ± 2.9^*	210. ± 4	1.06 ± 0.08	0.12 ± 0.02
N1(M813A)	M4	11.0 ± 0.7	337 ± 19	0.168 ± 0.008^*	0.082 ± 0.003
N1(F817A)	M4	12.1 ± 0.6	430 ± 30	ND	ND

ND, not determined; NE, no effect.
↵^a The lowest concentration of glutamate tested (3 nM) elicited currents greater than 100 nA from GluN1/GluN2D(Y578A) receptors. Therefore, the EC₅₀ of glutamate was calculated by fixing the minimum current to be 0 pA.
↵* P < 0.05 versus GluN2D, one-way analysis of variance with Dunnett’s post hoc test.