Table 1.
Quantitative analysis of peptide competition for 125I-glucagon binding and cell surface expression of WT and mutant GCGRs
| Mutant | Glucagon pIC50 ± S.E.a | Peptide 15 pIC50 ± S.E.a | Expression (% of WT)b |
|---|---|---|---|
| WT-GCGR | 7.47 ± 0.03 | 6.52 ± 0.03 | 100 ± 0 |
| Q1421.40bA | 7.03 ± 0.07c ** | 6.29 ± 0.07 | 80 ± 5 |
| Y1451.43bA | Nbd | Nb | 38 ± 4*** |
| Y1491.47bA | Nb | Nb | 103 ± 3 |
| K1872.60bA | 7.98 ± 0.09*** | 7.11 ± 0.05*** | 78 ± 8 |
| V1912.64bA | Nb | Nb | 119 ± 11 |
| I1942.67bA | 7.57 ± 0.05 | 6.78 ± 0.06* | 94 ± 8 |
| Y2022.75bA | Nb | Nb | 74 ± 4 |
| M2313.36bA | 7.60 ± 0.05 | 6.58 ± 0.06 | 95 ± 5 |
| Q2323.37bA | 7.02 ± 0.09*** | 6.20 ± 0.11* | 83 ± 4 |
| I2353.40bA | 7.34 ± 0.09 | 6.34 ± 0.10 | 71 ± 6* |
| N2383.43bA | 7.22 ± 0.09 | 6.42 ± 0.09 | 41 ± 2*** |
| W295 ECL2A | Nb | Nb | 68 ± 6* |
| S297 ECL2A | 7.59 ± 0.06 | 6.65 ± 0.06 | 62 ± 6* |
| N298 ECL2A | 6.90 ± 0.13*** | Nb | 68 ± 14* |
| R3085.40bA | Nb | Nb | 71 ± 7* |
| N3185.50bA | Nb | Nb | 80 ± 3 |
| H3616.52bA | 7.11 ± 0.08* | 6.60 ± 0.07 | 85 ± 3 |
| E3626.53bA | 6.98 ± 0.15*** | Nb | 67 ± 8* |
| R3787.35bA | 7.17 ± 0.08* | 6.79 ± 0.07* | 115 ± 5 |
| L3827.39bA | Nb | Nb | 84 ± 5 |
| D3857.42bA | 7.65 ± 0.06 | 6.76 ± 0.06 | 65 ± 4* |
| L3867.43bA | Nb | Nb | 86 ± 16 |
| S3897.46bA | 7.28 ± 0.08 | 6.38 ± 0.09 | 90 ± 8 |
| Q3927.49bA | 7.01 ± 0.07*** | 6.25 ± 0.13* | 70 ± 8* |
a pIC50 values are shown as means ± S.E. of at least three independent experiments.
b Cell surface expression was detected by flow cytometry and is reported as percentage of WT-GCGR.
c Data from Fig. S5 were fit to a three-parameter logistic equation. Statistical evaluation was performed using one-way analysis of variance and Dunnett's post test, *, p < 0.05; **, p < 0.001; ***, p < 0.0001 compared with WT control.
d Nb, insufficiently robust binding to enable a curve to be fitted.