Native hGLP-2(1-33) binds to the hGLP2-R with highest affinity among the tested ligands
In order to determine whether agonists and antagonists competed similarly, we measured heterologous binding (figure 3) by displacing the two radioligands with the four unlabeled peptides; hGLP-2(1-33), hGLP-2(3-33), hGLP-2(1-33,M10Y) and hGLP-2(3-33,M10Y). Overall, all four ligands were able to compete with both radioligands, with no significant differences in their binding affinities whether using the agonist or the antagonist radioligand (figure 3a and table 2). However, native hGLP-2(1-33) had a 4- to 5-fold higher affinity compared to the other three hGLP-2 variants (figure 3 and table 2). The decreased affinity of hGLP-2(1-33,M10Y) compared to hGLP-2(1-33) is consistent with the slightly decreased potency for hGLP-2(1-33,M10Y) compared to hGLP-2(1-33) (figure 1b).