(A) Labeling
of live cells with LUXendin492, LUXendin551, and LUXendin615. SNAP-GLP1R:CHO-K1
cells were incubated with LUXendin492 (LUX492), LUXendin551 (LUX551), and LUXendin615 (LUX615)
before orthogonal SNAP-labeling with either cell-impermeable SBG-TMR
or SBG-SiR and confocal imaging (nuclei were stained using Hoechst33342)
(scale bar = 10 μm) (n = three images from
experiments performed in duplicate). (B) Labeling efficiency of LUXendin492, LUXendin551, and LUXendin615 in SNAP-GLP1R:CHO-K1 cells, quantified as the proportion of SNAP+/LUX+ cells (versus total SNAP-labeled cells) (n = 6 wells). (C) LUXendin492, LUXendin551, and LUXendin615 label SNAP-GLP1R:INS1 832/3 but not
INS1 832/3 GLP1R–/– cells. (D) Additionally,
endogenous GLP1R can be visualized with LUXendin551 in
INS1 832/3 cells, which express the receptor at lower levels than
in islets (scale bars = 10 μm).