TABLE 1.
Pharmacological data of GIPR variants, R190Q, E288G and the double mutant.
| Binding |
cAMP accumulation |
β -arrestin 2 recruitment |
|||||||
| Bmax | pIC50 | Fmut | Emax | pEC50 | Fmut | Emax | pEC50 | Fmut | |
|
| |||||||||
| Missense variant | % of WT ± SEM | pIC50 ± SEM | (KD mutation/KD Wild-type) | % of WT ± SEM | LogEC50 ± SEM | (EC50 mutation/EC50 Wild-type) | % of WT ± SEM | pEC50 ± SEM | (EC50 mutation/EC50 Wild-type) |
| GIPR (WT) | 100 | 8.6 ± 0.2 | 96 ± 1.4 | 11 ± 0.1 | 98 ± 2.7 | 9.1 ± 0.1 | |||
| R190Q | 30 ± 11 | 8.3 ± 0.2 | 1.8 | 75 ± 2.8 | 8.0 ± 0.1 | > 250 | 9.0 ± 2.5 | 9.1 ± 0.7 | 0.9 |
| E288G | 13 ± 6.1 | 8.4 ± 0.3 | 1.4 | 90 ± 6.2 | 8.4 ± 0.2 | > 250 | 8.6 ± 2.5 | 9.6 ± 0.8 | 0.3 |
| R190Q;E288G | 0.70 ± 1.4 | 8.4 ± 0.5 | 1.5 | NA | NA | NA | 12 ± 2.8 | 8.0 ± 0.6 | 12.5 |
All data were fitted with three-parameter logistic curve to obtain pEC50 and Emax. pEC50 and pIC50 represent the negative logarithm of agonist concentration in molar that produces half the maximal response/inhibition. Bmax is characterized as the maximum specific binding normalized to wild-type GIPR. Emax is characterized as the maximal response normalized to wild-type GIPR. Fmut is the fold change in potency, EC50 and in affinity, KD mutant, between mutants and wildtype receptor, calculated as EC50 mutant/EC50 wildtype and KD mutant/KD wildtype. Data represent the mean ± SEM of at least three independent experiments performed in duplicate. NA, no activation observed.