Extended Data Fig. 1 |. Expression and labeling of functional Sf-mGluR2 with self-healing fluorophores in living CHO cells.
a, The SNAPf tag is a modified O6-alkylguanine-DNA alkyltransferase enzyme that forms covalent linkages with benzylguanine (BG)-fluorophores. b, Dose-response curve for bioluminescence resonance energy transfer (BRET)-based cAMP inhibition assay confirming Sf-mGluR2 functionality. Global fits from three independent experiments each performed in triplicate. Error bars represent standard error of the mean (SEM). The mean Log EC50 with standard error is shown. c, Schematic of LEx-FITR CHO cells expressing the tet repressor (TetR) and with integrated receptor cDNA under control of the crippled CMV promoter (PcrCMV), two tetracycline operator 2 (2XTO2) sites, and weak Kozac sequence. Note that LEx-FITR cells were selected for a Flp-In site that leads to very low basal expression after receptor cDNA integration. d, Chemical structures of LD555p-BG and LD655-BG. Absorption (left plots) and emission (right plots) spectra of recombinantly expressed and purified SNAPf labeled with e, LD555p and f, LD655.