Fig. 2 |. Structures of bitopic ligands bound to μOR.

a,e, Cryo-EM structure of C5 guano (a) and C6 guano (e) bound to μOR–G_i–scFv16 complex coloured by subunit. b,f, View of the C5 guano (b) and C6 guano (f) cryo-EM density. The cryo-EM maps are contoured at 5.0σ. The functional groups of the bitopic ligands target site 2 above the Na⁺-binding site, as expected. c,g, Salt-bridge interactions between C5 guano (c) or C6 guano (g) and residues in the μOR pocket. d,h, Cation–π interactions between C5 guano (d) or C6 guano (h) and residues in the μOR pocket.