Figure 2.

Two-dimensional representation of the interactions between (S)-nicotine or (S)-6-hydroxynicotine and the NIC-binding residues of the α9-α9 interface of α9 nAChRs (A,B), α3-β2 (C,D) and α5-α3 (E,F) interfaces of α3β2α5 nAChRs (2:2:1 stoichiometry) and α3-β4 (G,H) and α5-α3 (I,J) interfaces of α3β4α5 nAChRs (2:2:1 stoichiometry). The residues marked with * are identified in the literature as interacting with the ligand, while the encircled residues are new residues putatively interacting with the ligand. The hydrogen bonds and the hydrophobic interactions between the residues and the corresponding atoms of the ligands are displayed according to Ligplot⁺ software v2.2. The residues marked with “+” and “–” belong to the principal and complementary sides, respectively.