TABLE 2.
Summary of BZD concentration response data and binding data for WT and mutant α1β2γ2 GABAARs
Data are mean ± S.E.M. for n experiments. The loop where each mutation is located is indicated. Maximal potentiation is calculated as [(IGABA + BZD/IGABA) − 1]. The values for BZD binding affinities (Ki) were determined previously and the ratio of mutant to WT binding affinity is shown. Values significantly different from wild type α1β2γ2 are indicated.
| Loop | Receptor | Flurazepam |
Eszopiclone |
Zolpidem |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max Potentiation | EC50 | n | Mut/WT Kia | Max Potentiation | EC50 | n | Mut/WT Kib | Max Potentiation | EC50 | n | Mut/WT Kib | ||
| nM | nM | nM | |||||||||||
| WT αβγ | 2.3 ± 0.2 | 442 ± 34 | 3 | 1.0 | 2.8 ± 0.3 | 55 ± 8.5 | 8 | 1.0 | 2.8 ± 0.2 | 76.9 ± 27.4 | 6 | 1.0 | |
| A | αD97Cβγ | 0.8 ± 0.2** | 941 ± 140 | 3 | 1.1 ± 0.2** | 166 ± 49 | 3 | N.D. | 2.5 ±0.2 | 331 ± 18 | 3 | N.D. | |
| A | αF99Cβγ | 0.1 ± 0.0** | 3 | -0.5 ± 0.0** | 1400 ± 290** | 3 | 8.1** | 0.7 ± 0.2** | 3670 ± 1900** | 3 | 2.9* | ||
| B | αG157Cβγ | 0.9 ± 0.2** | 1620 ± 760 | 4 | 0.7 ± 0.1** | 1230 ± 140** | 3 | 42** | 1.3 ± 0.1* | 2820 ± 610** | 3 | 20** | |
| B | αA160Cβγ | 1.0 ± 0.2** | 368 ± 14 | 3 | 0.8 ± 0.1** | 140 ± 47 | 3 | 1.2 | 1.4 ± 0.1* | 118 ± 13 | 3 | 1.3 | |
| B | αT162Cβγ | 2.1 ± 0.1 | 500 ± 53 | 3 | 2.5 ± 0.5 | 131 ± 20 | 3 | 0.7 | 2.5 ± 0.3 | 410 ± 84 | 3 | 1.8 | |
| C | αG200Cβγ | 2.0 ± 0.0 | 454 ± 83 | 3 | 3.7 ± 0.5 | 230 ± 8.1 | 4 | 2.4** | 2.4 ± 0.5 | 996 ± 481** | 3 | 9.7** | |
| C | αV202Cβγ | 1.4 ± 0.4* | 922 ± 165 | 3 | 2.2 ± 0.4 | 522 ± 130** | 3 | 5.0** | 3.2 ± 0.3 | 2490 ± 250** | 3 | 9.0** | |
| C | αS204Cβγ | 1.5 ± 0.1 | 305 ± 43 | 3 | 1.7 ± 0.2 | 139 ± 39 | 3 | 1.2 | 3.6 ± 0.4 | 2100 ± 280** | 3 | 7.0** | |
| C | αS205Cβγ | 2.0 ± 0.1 | 366 ± 68 | 3 | 3.2 ± 0.2 | 75 ± 21 | 3 | 0.7 | 2.4 ± 0.2 | 143 ± 63.4 | 3 | 0.7 | |
| C | αT206Cβγ | 1.4 ± 0.3 | 946 ± 188 | 3 | 0.4 ± 0.0** | 50.9 ± 19.1 | 3 | 0.02** | 1.2 ± 0.2* | 245 ± 42 | 3 | 1.2 | |
| C | αY209Cβγ | 0.7 ± 0.1** | 2770 ± 649** | 3 | 0.8 ± 0.2* | 766 ± 250** | 3 | N.D. | 0.9 ± 0.2** | 14,300 ± 2300** | 3 | N.D. | |
| C | αV211Cβγ | 2.3 ± 0.1 | 511 ± 93 | 3 | 3.0 ± 0.4 | 115 ± 21 | 3 | 1.2 | 4.9 ± 0.1** | 356 ± 117 | 3 | 1.1 | |
| E | αβγT126C | 2.5 ± 0.3 | 280 ± 35.7 | 3 | 3.4 ± 0.2 | 14.4 ± 4.1 | 3 | 1.4 | 3.9 ± 0.2 | 9.6 ± 1.7 | 3 | 1.2 | |
| E | αβγM130C | 1.8 ± 0.2 | 305 ± 90 | 3 | 3.1 ± 0.5 | 24.5 ± 7.7 | 3 | 2.0* | 3.0 ± 0.3 | 4.4 ± 0.4 | 3 | 0.3** | |
| E | αβγR132C | 1.9 ± 0.1 | 264 ± 76.7 | 3 | 2.2 ± 0.3 | 12.5 ± 3.1 | 3 | 2.2* | 3.3 ± 0.2 | 7.03 ± 1.28 | 3 | 0.6* | |
| E | αβγL140C | 2.1 ± 0.1 | 330 ± 65 | 3 | 2.8 ± 0.2 | 12.6 ± 1.4* | 4 | 0.9 | 3.7 ± 0.2 | 12.1 ± 2.7 | 3 | 1.0 | |
| E | αβγT142C | 1.0 ± 0.0** | 561 ± 58 | 3 | 2.1 ± 0.5 | 148 ± 39** | 3 | 10* | 2.7 ± 0.3 | 980 ± 260** | 3 | 21** | |
| E | αβγR144C | 0.0 ± 0.0** | 3 | 0.2 ± 0.0** | 3 | 3.5** | 1.0 ± 0.2** | 22.5 ± 9.4 | 3 | 0.6 | |||
| F | αβγR185C | 1.7 ± 0.2 | 317 ± 82 | 3 | 2.4 ± 0.2 | 10.4 ± 1.5* | 3 | 1.4 | 2.0 ± 0.4 | 10.0 ± 2.2 | 3 | 1.1 | |
| F | αβγE189C | 1.7 ± 0.2 | 645 ± 78 | 3 | 1.3 | 3.1 ± 0.2 | 12.2 ± 3.0* | 4 | 6.3 ± 0.4** | 1838 ± 636** | 5 | 1.8a | |
| F | αβγR194C | 1.4 ± 0.1 | 332 ± 53 | 3 | 1.7 ± 0.4 | 12.8 ± 3.4 | 3 | 1.3 | 1.7 ± 0.8 | 21.2 ± 8.3 | 3 | 1.0 | |
| F | αβγR197C | 0.6 ± 0.3** | 494 ± 48 | 3 | 0.4* | 0.4 ± 0.0** | 6.0 ± 2.1* | 3 | 0.8 ± 0.2** | 13.8 ± 2.3 | 4 | 0.4a | |
Mut, mutation; N.D., not detectable.
a
Values from Hanson and Czajkowski (2008).
b
Values from Hanson et al. (2008).
*
p < 0.05 significantly different from wild-type α1β2γ2.
**
p < 0.01 significantly different from wild-type α1β2γ2.