The binding sites for cocaine and dopamine in the dopamine transporter overlap.
Cocaine is a widely abused substance with psychostimulant effects that are attributed to inhibition of the dopamine transporter (DAT). We present molecular models for DAT binding of cocaine and cocaine analogs constructed from the high-resolution structure of the bacterial transporter homolog LeuT. Our models suggest that the binding site for cocaine and cocaine analogs is deeply buried between transmembrane segments 1, 3, 6 and 8, and overlaps with the binding sites for the substrates dopamine and amphetamine, as well as for benztropine-like DAT inhibitors. We validated our models by detailed mutagenesis and by trapping the radiolabeled cocaine analog [3H]CFT in the transporter, either by cross-linking engineered cysteines or with an engineered Zn2+-binding site that was situated extracellularly to the predicted common binding pocket. Our data demonstrate the molecular basis for the competitive inhibition of dopamine transport by cocaine.
Beuming
Thijs
T
Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, New York 10021, USA.
Kniazeff
Julie
J
Bergmann
Marianne L
ML
Shi
Lei
L
Gracia
Luis
L
Raniszewska
Klaudia
K
Newman
Amy Hauck
AH
Javitch
Jonathan A
JA
Weinstein
Harel
H
Gether
Ulrik
U
Loland
Claus J
CJ
D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive / Q000187:drug effects; D019556:COS Cells; D002522:Chlorocebus aethiops; D003042:Cocaine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D050483:Dopamine Plasma Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed / Q000379:methods; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000502:physiology; D013329:Structure-Activity Relationship; D013997:Time Factors; D014162:Transfection / Q000379:methods
D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; C021279:(1R-(exo,exo))-3-(4-fluorophenyl)-8-methyl-8- azabicyclo(3.2.1)octane-2-carboxylic acid, methyl ester; D003042:Cocaine; D004298:Dopamine