Mutations at NR2A(Phe-637/823) can alter glutamate potency and
desensitization. A and B, average EC50 values
for glutamate activation of peak (A) and steady-state (B)
current in lifted cells expressing NR1 and wild type NR2A subunits
(F/M) or NR2A subunits containing various mutations at Phe-637 and
Met-823. *, EC50 values that are significantly different from that
for wild type NR1/NR2A subunits (*, p < 0.05; **, p <
0.01; ANOVA followed by Dunnett's test). Results are means ± S.E. of
5–8 cells. C, average values of maximal steady-state to peak
current ratio (Iss/Ip) in lifted cells
coexpressing NR1 and wild type NR2A subunits (F/M) or NR2A subunits
containing various mutations at Phe-637 and Met-823. Currents were activated
by 300 μm glutamate in the presence of 50 μm
glycine and 10 μm EDTA. *, values that differed significantly
from that for wild type NR1a/NR2A subunits (**, p < 0.01; ANOVA
followed by Dunnett's test). Results are means ± S.E. of 5–8
cells. D, graph plots values of maximal
Iss/Ip versus glutamate log
EC50 for steady-state current in the series of mutants. Maximal
Iss/Ip was significantly correlated
with glutamate log EC50 for steady-state (R2 =
0.349, p < 0.05) but not peak (R2 = 0.0515,
p > 0.05; results not shown) current. The line shown is
the least-squares fit to the data. Values for wild type, NR2A(F637A), and
NR2A(F637W) are from Ref.
24.