Fig. 9: LUXendin555 allows in vivo labeling of islets.

a–c LUXendin555 labels YFP-AD293_SNAP-GLP1R a but not YFP-AD293 b controls with max labeling at 600 nM c (n = 3 independent assays) (×10 scale bar = 213 µm; ×100 scale bar = 21 µm). d Surface GLP1R expression is similar in LUXendin555− (LUX555), LUXendin645− (LUX645), and 250 nM Exendin4(9–39)-treated islets (100 nM Ex4, +ve control) (representative images shown above each bar) (one-way ANOVA with Bonferroni’s test; F = 173.3, DF = 3) (n = 12 islets, seven animals, three separate islet preparations) (scale bar = 17 µm). e LUXendin555 behaves as an antagonist in HEK-SNAP_GLP1R cells using HTRF-based assays (n = 4 independent assays in duplicate). f LUXendin555 displays agonist activity in CHO-K1-SNAP_GLP1R cells, as assessed using luciferase-based detection (GLO) (n = 3 independent assays) (positive allosteric modulation was achieved using 25 µM BETP). g Schematic depicting the two-photon imaging set up for visualization of the intact pancreas in mice. h Representative image showing that LUXendin555 (100 pmol/g, IV) labels cell membranes in an islet surrounded by the vasculature in vivo (n = 3 animals) (scale bar = 50 µm). LUXendin645 and LUXendin555 were applied to cells/islets at 100 and 250 nM, respectively. GLP-1 glucagon-like peptide-1; Ex9 Exendin4(9–39); Ex4 Exendin4(1–39). Mean ± s.e.m. are shown. **P < 0.01 for all statistical tests. Source data are provided as a Source Data file.