Cl− binding site in hSERT. Illustration depicts hSERT labeled helices (TM) and residue side chains identified by Forrest et al. (1) to coordinate Cl− binding in the human serotonin transporter (hSERT) (stick rendering). The Cl− (red) and Na+ (blue) ions are shown as labeled spheres. The figure was generated in Pymol (DeLano Scientific LLC, San Carlos,. California) using coordinates from a LeuTAa-hSERT homology model we have developed in our studies.