Extended Data Fig. 1: Site-specific labeling of mGluR2 by click chemistry.
From: Conformational rearrangement during activation of a metabotropic glutamate receptor
a, Schematic showing site-specific fluorescent labeling of mGluR2, with the unnatural amino acid 4-azido-L-phenylalanine at residue 548, by copper-catalyzed azide-alkyne click reaction. b, Donor (green: Cy3) and acceptor (red: Cy5) fluorophores conjugated to the CRD of inactive mGluR5 (PDB 6N52) at the position corresponding to residue 548 in mGluR2 (top). Representative confocal microscope image of HEK293T cells expressing 548UAA with the cell surface population labeled with donor (green: Cy3) and acceptor (red: Cy5) fluorophores through click chemistry (bottom). Scale bars, 10 µm. c, Unprocessed image of non-reducing 4-20% polyacrylamide gel electrophoresis of cell lysate from HEK293T cells expressing 548UAA and labeled by Cy5-alkyne. The gel is imaged with 633 nm excitation wavelength and 670-BP30 emission filter. Lane A: protein ladder; lane B: cell lysate; lane C: Cy5-alkyne dye. Results are representative of an individual experiment. d, Image of HEK293T cells expressing 548UAA and labeled with donor (green: Cy3) and acceptor (red: Cy5) fluorophores through click chemistry during live-cell FRET experiments. Scale bars, 10 µm. Results are representative of all titration and max response experiments for the 548UAA construct (N=21 independent experiments).
