Agonist pharmacology of the GlyR α1 subunit mutants K104A, F108A, and T112A
| Ligand | α11-160 | α1K104A | α1F108A | α1T112A | ||||
|---|---|---|---|---|---|---|---|---|
| EC50 | n | EC50 | n | EC50 | n | EC50 | n | |
| mM | mM | mM | mM | |||||
| Glycine | 0.20 ± 0.03 | (5) | 0.15 ± 0.01 | (19) | 0.06 ± 0.01 | (7) | 0.11 ± 0.02 | (9) |
| l-alanine | 3.10 ± 0.80 | (5) | 1.14 ± 0.11 | (5) | 0.73 ± 0.13 | (3) | 1.64 ± 0.48 | (5) |
| d-alanine | 9.00 ± 1.30 | (6) | 1.44 ± 0.29 | (4) | 0.72 ± 0.08 | (3) | 0.99 ± 0.35 | (4) |
| l-serine | 5.10 ± 0.70 | (5) | 4.26 ± 0.97 | (5) | 0.971-150 | 5.95 ± 1.19 | (3) | |
| d-serine | 1-a | 22.37 ± 7.00 | (4) | 6.411-150 | 22.32 ± 7.00 | (4) | ||
| β-alanine | 0.60 ± 0.30 | (5) | 0.24 ± 0.04 | (4) | 0.09 ± 0.02 | (5) | 0.23 ± 0.04 | (4) |
| Taurine | 1.70 ± 0.10 | (18) | 0.95 ± 0.09 | (5) | 0.79 ± 0.24 | (4) | 1.10 ± 0.24 | (6) |
| β-ABA | 5.60 ± 0.80 | (8) | 4.32 ± 0.66 | (10) | 1.88 ± 0.45 | (2) | 9.67 ± 1.73 | (3) |
| β-AIBA | 8.70 ± 0.8 | (5) | 21.22 ± 4.47 | (4) | n.d. | n.d. | ||
| Imax | n | Imax | n | Imax | n | Imax | n | |
|---|---|---|---|---|---|---|---|---|
| % | % | % | % | |||||
| Taurine | 31.9 ± 2.8 | (18) | 73.2 ± 1.7 | (5) | 90.7 ± 3.5 | (4) | 85.9 ± 5.6 | (7) |
| β-ABA | 7.1 ± 1.9 | (8) | 63.7 ± 2.5 | (10) | 66.5 ± 0.2 | (2) | 77.6 ± 6.8 | (3) |
| β-AIBA | 6.5 ± 2.8 | (5) | 10.8 ± 0.04 | (4) | n.d. | n.d. |
Amino acid responses were recorded from oocytes injected with the different mutant α1 cRNAs as described. The agonist concentrations eliciting a half-maximal response (EC50; mean ± S.E.M.) of n experiments were calculated from least-square fits of the corresponding dose-effect curves. Imax values of taurine, β-AIBA, and β-ABA are given as a fraction of the maximal glycine current.