Table 3 Results of TEVC concentration–response experiments with GluN1-4a/GluN2B potentiating mutants

From: Structural elements of a pH-sensitive inhibitor binding site in NMDA receptors

Constructs

93-31 pH 7.6

IC50 (μM), % response

nH (n)

93-5 pH 7.6

IC50 (μM), % response

nH (n)

Ifenprodil, pH 7.6

IC50 (μM), % response

nH (n)

GluN1-4a/GluN2B (WT)b

1.2 ± 0.46, 34%a

nH 0.8 (6)

0.12 ± 0.01, 39%c

nH 0.6 (5)

0.12 ± 0.02, 35%d

nH 1.0 (7)

GluN1-4a(Y109W)b

1.3 ± 0.28, 177%e

nH 1.0 (8)

0.52 ± 0.20, 265%e

nH 0.9 (7)

ND, 115%f

nH ND (9)

GluN1-4a(H134A)b

1.8 ± 0.23, 153%e

nH 1.1 (6)

0.32 ± 0.08, 140%e

nH 0.7 (6)

ND, 105%f

nH ND (9)

  1. Concentration–response curves were generated in the presence of 100 μM glutamate and 30 μM glycine, and the listed ligands, and normalized against current from glutamate and glycine alone. IC50 values are given ± S.E.M. (n): number of independent replicates. In all of the recordings, Hill coefficient (nH) ranged from 0.6 to 1.1, and were not determined when the potentiation was less than 30% at the highest concentrations tested. ND not determined
  2. aThe steady-state response was determined as a percentage of the current at 3 μM 93-31, pH 7.6
  3. bTo prevent run-down of current, experiments in the second table (WT, Y109W, and H134A) were conducted in oocytes co-injected with 13 nL of 100 mM BAPTA
  4. cCurrent at 1 μM 93-5
  5. dCurrent at 1 μM ifenprodil
  6. eThe GluN1-4a(Y109W) and GluN1-4a(H134A) mutants converted 93-series ligands into potentiators; EC50 value and maximal potentiation given
  7. fCurrent at maximal ifenprodil potentiation
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