GR: Dopamine transporter mutants with cocaine resistance and normal dopamine uptake provide targets for cocaine antagonism

Cocaine’s blockade of dopamine reuptake by brain dopamine transporters (DAT) is a central feature of current understanding of cocaine reward and addiction. Empirical screening of small-molecule chemical libraries has thus far failed to provide suc-cessful cocaine blockers that allow dopamine reuptake in the presence of cocaine and provide cocaine “antagonism”. We have approached this problem by assessing expression, dopa-mine uptake, and cocaine analog affinities of 56 DAT mutants in residues located in or near transmembrane domains likely to play significant roles in cocaine recognition and dopamine up-take. A phenylalanine-to-alanine mutant in putative DAT trans-membrane domain 3, F154A, retains normal dopamine uptake, lowers cocaine affinity 10-fold, and reduces cocaine ste-reospecificity. Such mutants provide windows into DAT struc