Figure 6
Model of the 5-HT 3 R binding site. The model illustrates the major points discussed in the text. Lerisetron is shown spanning the region between the D and E loops of the receptor. Both loops are illustrated as β-sheets as described. The side chains are presumed to point in or out of the page depending on their position. W89, R91, Y140, Y142 and Y152 all presumably extend into the binding site. The terminal piperazine nitrogen is shown interacting primarily with Y142, but is also capable of forming an interaction with Y152. Y152 may also form an interaction with the second piperazine nitrogen. W89 is illustrated as forming an aromatic interaction with the benzimidazole. While R91 is shown in close contact to the N-benzyl group, the data support only a weak interaction at this point.