Figure 1.

(Top) Ribbon representation of α-CTxMII backbone with licorice representations of critical amino acids at positions 5, 9, 11, and 12. (Middle) Licorice representation of acetylcholine, with the carbonyl oxygen labeled as O_T, the ester linkage oxygen as O_I and the carbon bound to the trimethyl ammonium group as C2. (Bottom) Top view of the α₃β₂-nAChR ligand binding domain in surface representation with docking grid boxes around each of the 5 C-loop binding regions, the channel subunits are color coded with orange representing α₃ and yellow representing β₂ subunits. The α-CTxMII is represented bound to a C-loop region between α₃ and β₂ subunits (transparent blue surface with amino acids in licorice).