 The ring falls tight into the receptor pocket, stacked between two phenylalanines.Amine of the indole group forms a hydrogen bond with S219 residue in TM 5 and hydroxide substituent of the indole forms hydrogen bonds both with residue S131 in TM 3 and I332 in TM 6.There is also a strong Van der Waals interaction between the indole and I332 in TM 6.