Table 2.

A list of relevant x-ray co-crystal structures of transporters discovered to date bound to various ligands.

Transporter	Ligand	Binding site/Conformation	Reference
LeuT	Leucine	Substrate binding site (S1), outward-occluded	(Yamashita et al., 2005)
LeuT	Tryptophan	2 molecules bound, one at S1 and other at the external vestibule site, outward-open	(Singh et al., 2008)
LeuT	n-octyl-β-D-glucopyranoside detergent	External vestibule site, outward-open	(Quick et al., 2009)
LeuT	TCAs (desipramine, clomipramine, imipramine), SSRIs (sertraline, (R)/(S)-fluoxetine)	External vestibule site, outward-open	(Singh et al., 2007)
LeuBAT	Antidepressants (SSRIs, SNRIs, Clomipramine), Mazindol	S1, outward-open	(H. Wang et al., 2013)
dDAT	3,4-dichlorophenethylamine (DCP, a dopamine analog)	S1, outward-partially occluded	(K. H. Wang et al., 2015)
dDAT	cocaine, RTI-55, SNRIs, NRIs (nisoxetine, reboxetine), SSRIs, nortriptyline, dopamine, D-amphetamine, (+)-methamphetamine	S1, outward-open	(Penmatsa et al., 2015; K. H. Wang et al., 2015)
hSERT	(S)-citalopram	2 molecules bound, one at S1 and other at external vestibular site, outward-open	(Coleman et al., 2016)
hSERT	paroxetine	S1, outward-open	(Coleman et al., 2016)