- High affinity recognition of serotonin transporter antagonists defined by species-scanning mutagenesis. An aromatic residue in transmembrane domain I dictates species-selective recognition of citalopram and mazindol. Barker, E.L., Perlman, M.A., Adkins, E.M., Houlihan, W.J., Pristupa, Z.B., Niznik, H.B., Blakely, R.D. J. Biol. Chem. (1998)