Orientation of cobra α-neurotoxin bound to Lymnaea AChBP (PDB code 1YI5; Ref. 29). Left: principal (yellow) and complementary (blue) faces of AChBP and cobra α-neurotoxin (green) are shown as ribbons. Right: close-up view of the complex, with residues in finger II of α-neurotoxin shown as ball and stick (Trp25, Asp27, Phe29, Arg33, Arg36) and residues of the aromatic binding pocket of AChBP (Trp143, Tyr185, Tyr192, Trp53) shown as space-filling.