Overview of the GLP-1R-G4 complex. (a) Overview of the GLP-1R-G4, molecular surface of GLP-1R (gray), ECL2 (cyan), ECL3 (pink), ECD far N-terminus (yellow), G4 is represented as a ribbon (orange), with the O-GlcNAc moiety represented as spheres (green). (b) Mutation of V16 into AIB16 alters the side chain position of L142 residue (gray); initial conformation of L142side chain (magenta). Mutation of A8 into AIB8 alters the side chain position of F367 (gray); initial conformation of F367 side chain (magenta).