Sensitivity of mutant receptors to picrotoxin
| Combination | IC50 | Hill coefficient | Oocytes |
|---|---|---|---|
| μm | n | ||
| ρ1 | 3.28 ± 0.43 | 0.86 ± 0.03 | 6 |
| ρ1L301A | 970 ± 406 | 1.08 ± 0.10 | 6 |
| ρ1L301F | 119 ± 26 | 0.72 ± 0.04 | 6 |
| ρ1L301G | 4920 ± 1503 | 1.11 ± 0.15 | 6 |
| ρ1L301I | N.D. | N.D. | 6 |
| ρ1L301S | 1594 ± 573 | 1.02 ± 0.05 | 6 |
| ρ1L301T | 5454 ± 2987 | 0.95 ± 0.11 | 6 |
| ρ1L301V | N.D. | N.D. | 6 |
| ρ1L301Y | 192 ± 67 | 0.98 ± 0.07 | 6 |
All values are mean ± standard deviation. Picrotoxin-mediated antagonism of the ρ1 wild-type receptor, as well as the L301F and L301I mutants, were determined on currents activated by 3 μm GABA. Antagonism of the resting conductance was determined in the other mutants. The L301I mutation exhibited a 10% inhibition with 1000 μm picrotoxin, whereas the L301V mutation exhibited no antagonism at picrotoxin concentrations as high as 3000 μm.