5i74
From Proteopedia
X-ray structure of the ts3 human serotonin transporter complexed with Br-citalopram at the central site
Structural highlights
Function[SC6A4_HUMAN] Serotonin transporter whose primary function in the central nervous system involves the regulation of serotonergic signaling via transport of serotonin molecules from the synaptic cleft back into the pre-synaptic terminal for re-utilization. Plays a key role in mediating regulation of the availability of serotonin to other receptors of serotonergic systems. Terminates the action of serotonin and recycles it in a sodium-dependent manner.[1] [2] [3] Publication Abstract from PubMedThe serotonin transporter (SERT) terminates serotonergic signalling through the sodium- and chloride-dependent reuptake of neurotransmitter into presynaptic neurons. SERT is a target for antidepressant and psychostimulant drugs, which block reuptake and prolong neurotransmitter signalling. Here we report X-ray crystallographic structures of human SERT at 3.15 A resolution bound to the antidepressants (S)-citalopram or paroxetine. Antidepressants lock SERT in an outward-open conformation by lodging in the central binding site, located between transmembrane helices 1, 3, 6, 8 and 10, directly blocking serotonin binding. We further identify the location of an allosteric site in the complex as residing at the periphery of the extracellular vestibule, interposed between extracellular loops 4 and 6 and transmembrane helices 1, 6, 10 and 11. Occupancy of the allosteric site sterically hinders ligand unbinding from the central site, providing an explanation for the action of (S)-citalopram as an allosteric ligand. These structures define the mechanism of antidepressant action in SERT, and provide blueprints for future drug design. X-ray structures and mechanism of the human serotonin transporter.,Coleman JA, Green EM, Gouaux E Nature. 2016 Apr 21;532(7599):334-9. doi: 10.1038/nature17629. Epub 2016 Apr 6. PMID:27049939[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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