Fig. 9.

Cocaine molecule docked to the channel domain of the homology model of the human α₃β₄ nAChR with the subunit stoichiometry of (α₃)2(β₄)3. a Top view (from the extracellular side) of the channel-lining domain (with only M2 domains for clarity). The docked cocaine is located in the center of the pore and has a potential hydrogen bond with α₃Ser247 (Chain A). b Side view of the channel-lining domain, with one α₃ subunit (Chain D) removed from the front for clarity. The docked cocaine was located immediately above the selectivity filter (β₄Glu241) up to the level at the 6′ position (α₃Ser247, β₄Ser248) of the second transmembrane domain (M2) with two potential π-anion interactions with two β₄Glu241 residues of Chains C and D. The docked cocaine molecule was below the putative channel gate at the 9′ position (α₃Leu250, β₄Leu251)