2.A.22.1.7
Dopamine transporter.  The 3-d structure is known to 3.0 Å resolution (Penmatsa et al. 2013).  The crystal structure, bound to the tricyclic antidepressant nortriptyline, shows the transporter locked in an outward-open conformation with nortriptyline wedged between transmembrane helices 1, 3, 6 and 8, blocking the transporter from binding substrate and from isomerizing to an inward-facing conformation. Although the overall structure is similar to that of its prokaryotic relative LeuT, there are multiple distinctions, including a kink in transmembrane helix 12 halfway across the membrane bilayer, a latch-like carboxy-terminal helix that caps the cytoplasmic gate, and a cholesterol molecule wedged within a groove formed by transmembrane helices 1a, 5 and 7.