Functional cooperativity estimates for the interaction between BETP or Compound 2 and GLP-1R peptide ligands
Data derived from analysis of interaction concentration-response curves with an operational model of allosterism as defined in eqs. 4 and 5. pKb values are the negative logarithms for the functional affinity of the allosteric ligands; log αβ represents the composite cooperativity between the allosteric ligand and the orthosteric peptide ligand. Antilogarithms are shown in parentheses. Values represent the mean ± S.E.M. of four to six independent experiments performed in duplicate. Data were analyzed with one-way analysis of variance and Dunnett’s post test.
| Pathway | Allosteric Ligand | pKb | Log αβ (αβ) | |||
|---|---|---|---|---|---|---|
| Exendin-4 | GLP-1(7–36)NH2 | Oxyntomodulin | GLP-1(1–36)NH2 | |||
| cAMP | BETP | 5.01 ± 0.04 | 0.45 ± 0.20 (2.8) | 0.31 ± 0.18 (2.0) | 1.21 ± 0.17 (16)* | 0.20 ± 0.12 (1.6) |
| Cpd2 | 5.43 ± 0.29 | 0.24 ± 0.30 (1.7) | 0.22 ± 0.28 (1.7) | 1.48 ± 0.27 (29)* | 0.31 ± 0.17 (2.0) | |
| pERK1/2 | BETP | 5.46 ± 0.29 | –0.90 ± 0.21 (0.13)* | –1.03 ± 0.23 (0.09)* | −0.44 ± 0.19 (0.36) | −1.85 ± 0.88 (0.01) |
| Cpd2 | 5.29 ± 0.19 | –0.77 ± 0.21 (5.9) | –0.48 ± 0.17 (0.33) | −0.21 ± 0.13 (0.62) | −0.44 ± 0.20 (0.36) | |
| iCa2+ | BETP | 4.83 ± 0.16 | 1.0 ± 0.26 (10)* | 0.58 ± 0.19 (3.8) | 0.23 ± 0.11 (1.7) | NR |
| Cpd2 | 5.58 ± 0.38 | 0.28 ± 0.15 (1.9) | –0.20 ± 0.15 (0.63) | 0.14 ± 0.16 (1.4) | NR | |
| β-Arr1 | BETP | 5.42 ± 0.17 | –0.05 ± 0.04 (0.89) | –0.01 ± 0.02 (1.0) | 0.40 ± 0.17 (2.5) | NR |
| Cpd2 | 5.27 ± 0.18 | 0.72 ± 0.18 (5.2)* | 1.07 ± 0.19 (12)* | 1.05 ± 0.14 (11)* | NR | |
| β-Arr2 | BETP | 5.38 ± 0.16 | 0.18 ± 0.26 (1.5) | 0.67 ± 0.18 (4.7) | 0.54 ± 0.19 (3.5) | NR |
| Cpd2 | 5.30 ± 0.19 | 0.69 ± 0.20 (4.9)* | 1.06 ± 0.13 (11)* | 0.99 ± 0.19 (10)* | NR | |
β-Arr, beta arrestin; BETP, 4-(3-benzyloxyphenyl)-2-ethylsulfinyl-6-(trifluoromethyl)pyrimidine; Compound 2, 6.7-dichloro-2-methylsulfonyl-3-tert-butylaminoquinoxaline; iCa2+, intracellular calcium; NR, no response; pKb, negative logarithms for the functional affinity of the allosteric ligands.
↵* P < 0.05.