Minimal binding to other class B1 GPCRs for
[125I]-hGLP-2(1-33,M10Y) and
[125I]-hGLP-2(3-33,M10Y)
Given the high sequence similarity between class B1 receptors and their
peptide ligands, we next determined whether the two radioligands
cross-react with the closely related class B1 GPCRs; hGIPR, hGLP-1R,
hGCGR and hSecretinR, VPAC-1R, and VPAC-2R (figure 4a). While we
observed no specific binding for five of the six receptors, a low, but
significant binding was observed for both radioligands to the hGLP-1R
(Emax of 37.8% and 26.7% of the hGLP-2R binding) (figure 4b and
supplementary figure 1).
Furthermore, we tested the binding properties of both radioligands on
the mouse and rat GLP. Also here, we observed high-affinity binding
(figure 5a,b and table 2). The similar IC50 values of
hGLP-2(1-33) on the GLP-2R from the three species suggests overall
strong structural similarities between the receptors (table 2).