Table 2. Properties of Agonist-Activated ΔI and ΔF Responses at Mutant α3 GlyRsa.
| construct | EC50 (μM) | nH | Imax (μA) | ΔFmax (%) | n |
|---|---|---|---|---|---|
| α3-WT unlabeled ΔI | 74 ± 2 | 2.9 ± 0.2 | 5.4 ± 0.6 | 6 | |
| α3-WT labeled ΔI | 71 ± 2 | 2.9 ± 0.2 | 5.6 ± 0.5 | 6 | |
| α3-WT labeled ΔF | 6 | ||||
| α3-L421C unlabeled ΔI | 27.1 ± 0.3aaa | 2.5 ± 0.1 | 4.1 ± 0.2 | 3 | |
| α3-L421C labeled ΔI | 31 ± 1 | 2.6 ± 0.2 | 4.6 ± 0.4 | 4 | |
| α3-L421C labeled ΔF | –1.8 ± 0.1 | 4 | |||
| α3-R422C unlabeled ΔI | 35 ± 2aaa | 2.6 ± 0.3 | 3.7 ± 0.3 | 3 | |
| α3-R422C labeled ΔI | 23.9 ± 0.4 | 3.8 ± 0.2c | 4.9 ± 0.6 | 5 | |
| α3-R422C labeled ΔF | –1.2 ± 0.1 | 5 | |||
| α3-H423C unlabeled ΔI | 36 ± 1aaa | 3.0 ± 0.2 | 4.9 ± 0.3 | 3 | |
| α3-H423C labeled ΔI | 36 ± 2 | 3.6 ± 0.6 | 5.2 ± 0.4 | 4 | |
| α3-H423C labeled ΔF | –0.9 ± 0.1 | 4 | |||
| α3-E424C unlabeled ΔI | 52 ± 2aa | 2.8 ± 0.1 | 4.3 ± 0.5 | 4 | |
| α3-E424C labeled ΔI | 28.2 ± 0.5c | 2.8 ± 0.2 | 4.9 ± 0.7 | 5 | |
| α3-E424C labeled ΔF | –0.9 ± 0.2 | 5 | |||
| α3-W286F-L421C unlabeled ΔI | 898 ± 59aaa | 3.0 ± 0.4 | 3.9 ± 0.3 | 3 | |
| α3-W286F-L421C labeled ΔI | 165 ± 36bbb | 2.0 ± 0.3c | 2.5 ± 0.5 | 3 | |
| α3-W286F-L421C labeled ΔF | –2.1 ± 0.3 | 3 | |||
| α3-W286F-R422C unlabeled ΔI | 934 ± 70aaa | 3.3 ± 0.1 | 2.9 ± 0.2 | 3 | |
| α3-W286F-R422C labeled ΔI | 248 ± 44bbb | 2.4 ± 0.4c | 2.8 ± 0.3 | 4 | |
| α3-W286F-R422C labeled ΔF | –1.3 ± 0.2 | 4 | |||
| α3-W286F–H423C unlabeled ΔI | 742 ± 62aaa | 3.4 ± 0.4 | 3.3 ± 0.3 | 3 | |
| α3-W286F–H423C labeled ΔI | 277 ± 65bb | 1.8 ± 0.3bb | 2.7 ± 0.2 | 5 | |
| α3-W286F-H423C labeled ΔF | –1.5 ± 0.3 | 5 | |||
| α3-W286F-E424C unlabeled ΔI | 798 ± 82aaa | 3.0 ± 0.4 | 3.8 ± 0.5 | 3 | |
| α3-W286F-E424C labeled ΔI | 236 ± 35bbb | 1.8 ± 0.3bb | 2.8 ± 0.3 | 3 | |
| α3-W286F-E424C labeled ΔF | –1.8 ± 0.4 | 3 |
a
Electrophysiological and fluorescence data are shown in normal and bold type, respectively.
b
Significant difference to electrophysiological properties of unlabeled α1-WT GlyRs (unpaired Student’s t test, ap < 0.05, aap < 0.01, aaap < 0.001).
c
Significant difference to electrophysiological properties before labeling in the same mutant GlyR (paired Student’s t test, bp < 0.05, bbp < 0.01, bbbp < 0.001).