Voltage-dependent block by N1-DnsSpm at mutant NMDA receptors
| Subunit combination | Kd(0) | Mutant/wild-type2-a | zδ | Mutant/wild-type2-b | No. of oocytes |
|---|---|---|---|---|---|
| mm | |||||
| NR1a/NR2B series | |||||
| Wild-type NR1a/NR2B | 0.67 (0.57, 0.78) | 2.73 ± 0.05 | 21 | ||
| NR1a(W563L)/NR2B | 4.59 (3.97, 5.30)2-e | 6.9 | 2.86 ± 0.06 | 1.0 | 15 |
| NR1a(W608L)/NR2B2-c | 0.65 (0.45, 0.92) | 1.0 | 2.77 ± 0.09 | 1.0 | 8 |
| NR1a(W611L)/NR2B2-c | 0.62 (0.44, 0.88) | 0.9 | 2.78 ± 0.08 | 1.0 | 7 |
| NR1a(N616Q)/NR2B | 0.70 (0.59, 0.83) | 1.1 | 2.11 ± 0.062-e | 0.8 | 8 |
| NR1a(N616G)/NR2B2-c | 0.03 (0.03, 0.04)2-e | 0.05 | 2.73 ± 0.12 | 1.0 | 9 |
| NR1a(S617N)/NR2B | 0.84 (0.69, 1.03) | 1.3 | 2.72 ± 0.07 | 1.0 | 10 |
| NR1a(E621Q)/NR2B | 1.82 (1.56, 2.11)2-e | 2.7 | 2.63 ± 0.06 | 1.0 | 7 |
| NR1a(Y647L)/NR2B | 0.19 (0.16, 0.22)2-e | 0.3 | 2.66 ± 0.10 | 1.0 | 10 |
| NR1a/NR2B(W559L) | 0.36 (0.32, 0.40)f | 0.5 | 2.35 ± 0.042-e | 0.9 | 19 |
| NR1a/NR2B(W607L)2-d | N.D. | N.D. | |||
| NR1a/NR2B(W610L) | 0.88 (1.04, 0.74) | 1.3 | 2.81 ± 0.06 | 1.0 | 9 |
| NR1a/NR2B(N615Q) | 0.10 (0.08, 0.12)2-e | 0.2 | 2.24 ± 0.122-e | 0.8 | 8 |
| NR1a/NR2B(N616Q) | 3.44 (2.78, 4.26)2-e | 5.2 | 2.67 ± 0.08 | 1.0 | 12 |
| NR1a/NR2B(Y646L) | 1.90 (1.39, 2.59)2-e | 2.9 | 2.74 ± 0.11 | 1.0 | 12 |
| NR1a/NR2A series | |||||
| Wild-type NR1a/NR2A | 0.34 (0.29, 0.39) | 2.65 ± 0.05 | 22 | ||
| NR1a(W563L)/NR2A | 1.85 (1.37, 2.49)2-e | 5.5 | 2.69 ± 0.08 | 1.0 | 12 |
| NR1a(E621Q)/NR2A | 1.29 (1.12, 1.49)2-e | 3.8 | 2.69 ± 0.03 | 1.0 | 9 |
| NR1a/NR2A(N615Q) | 3.62 (3.05, 4.29)2-e | 10.7 | 2.56 ± 0.06 | 1.0 | 9 |
| NR1a/NR2A(W606L) | 0.18 (0.25, 0.13) | 0.5 | 2.57 ± 0.09 | 1.0 | 8 |
I–V curves were constructed by using voltage ramps (−150 to +30 mV over 6 sec) in the absence and presence of N1-DnsSpm. Values of K d(0) and zδ were determined by fitting data from voltage ramps to text eq. 3 as illustrated in Fig.7B.
↵2-a Ratio of K d(0)at mutant/K d(0) at wild-type.
↵2-b Ratio of zδ at mutant/zδ at wild-type.
↵2-c These experiments were carried out using 0.1 μm N1-DnsSpm. All other data in this table were from experiments using 1 μm N1-DnsSpm, except for wild-type NR1a/NR2B, at which 0.1 μm and 1 μm N1-DnsSpm were used. At wild-type NR1a/NR2B receptors, values ofK d(0) and zδ were not significantly different when 0.1 μm (6 oocytes) or 1 μm (15 oocytes) N1-DnsSpm was used, and data from those experiments have been pooled. In experiments using 1 μm(rather than 0.1 μm) N1-DnsSpm at NR1a(W608L)/NR2B and NR1a(W611L)/NR2B receptors, we found a significant (p < 0.01) decrease in K d(0) [meanK d(0) = 0.08 mm at NR1a(W608L)/NR2B and 0.17 mm at NR1a(W611L)/NR2B] and zδ (mean zδ = 2.04 at NR1a(W608L)/NR2B and 2.32 at NR1a(W611L)/NR2B), suggesting that these mutations may cause small disruptions of block by N1-DnsSpm.
↵2-d Voltage-dependent block at NR1a/NR2B(W607L) was very shallow and incomplete, presumably due to permeation of N1-DnsSpm through these channels (Fig. 8). Values of K d(0) are the geometric mean (−standard error, +standard error), and zδ values are the arithmetic mean ± standard error.
↵2-e p < 0.01,f p < 0.05 compared with wild-type NR1a/NR2 receptors (one-way analysis of variance with post hoc Dunnett’s test).