Table I.
Summary of D-serine concentration-response data and potentiation by extracellular Ca2+ at GluRδ2Lc mutants.
| D-serine + 0 mM Ca2+ | D-serine + 3 mM Ca2+ | Fold shift | Ca2+ potentiation (relative to baseline) |
|||||
|---|---|---|---|---|---|---|---|---|
| GluRδ2Lc mutant |
EC50 (μM) | nH | N | EC50 (μM) | nH | N | EC50 3mM / 0mM |
|
| GluRδ2Lc | 309 ± 8 | 1.0 | 12 | 2720 ± 90 | 2.1 | 10 | 8.8 | 3.8 ± 0.23 |
| R530K | n.d. | n.d. | n.d. | 3.3 ± 0.20 | ||||
| D742A | n.d. | n.d. | n.d. | 3.5 ± 0.11 | ||||
| E531A | 319 ± 10 | 1.1 | 8 | 705 ± 55 | 1.9 | 8 | 2.2 | 1.6 ± 0.08 |
| D535A | 1600 ± 80 | 2.3 | 10 | 1580 ± 240 | 2.2 | 8 | 1.0 | 1.0 ± 0.01 |
| D782A | 278 ± 11 | 1.0 | 12 | 304 ± 18 | 1.1 | 8 | 1.1 | 0.8 ± 0.02 |
| E531A+D535A | 10200 ± 1000 | 2.2 | 10 | 8770 ± 630 | 2.2 | 12 | 0.9 | 1.0 ± 0.04 |
| E531A+D782A | 8240 ± 180 | 2.3 | 5 | 7540 ± 140 | 2.4 | 6 | 0.9 | 0.9 ± 0.04 |
| D535A+D782A | 345 ± 31 | 1.0 | 6 | 351 ± 6 | 1.1 | 5 | 1.0 | 0.6 ± 0.01 |
| E531C+D782C | 1170 ± 180 | 0.8 | 6 | 897 ± 212 | 0.8 | 6 | 0.8 | 0.9 ± 0.01 |
| D535C+D782C | 472 ± 99 | 0.9 | 6 | 514 ± 90 | 1.0 | 4 | 1.1 | 0.9 ± 0.01 |
| P528C+L789C | 898 ± 192 | 1.1 | 7 | 1070 ± 200 | 0.8 | 4 | 1.2 | 0.9 ± 0.01 |
D-serine EC50 ± SEM in the presence and absence of extracellular Ca2+were used to calculate the fold shift in D-serine EC50. N is the number of oocytes used to generate the data, nH is the Hill slope, and n.d. indicates not determined. Ca2+ potentiation is the fold potentiation ± SEM of baseline spontaneously active GluRδ2Lc currents by the application of 3 mM Ca2+.