Details

Autor(en) / Beteiligte

• Tomlinson, Michael J.
• Krout, Danielle
• Pramod, Akula Bala
• Lever, John R.
• Newman, Amy Hauck
• Henry, L. Keith
• Vaughan, Roxanne A.

Titel

Identification of the benztropine analog [125I]GA II 34 binding site on the human dopamine transporter

Ist Teil von

• Neurochemistry international, 2019-02, Vol.123, p.34-45

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2019

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The dopamine transporter (DAT) is a neuronal membrane protein that is responsible for reuptake of dopamine (DA) from the synapse and functions as a major determinant in control of DA neurotransmission. Cocaine and many psychostimulant drugs bind to DAT and block reuptake, inducing DA overflow that forms the neurochemical basis for euphoria and addiction. Paradoxically, however, some ligands such as benztropine (BZT) bind to DAT and inhibit reuptake but do not produce these effects, and it has been hypothesized that differential mechanisms of binding may stabilize specific transporter conformations that affect downstream neurochemical or behavioral outcomes. To investigate the binding mechanisms of BZT on DAT we used the photoaffinity BZT analog [125I]N-[n-butyl-4-(4‴-azido-3‴-iodophenyl)]-4′,4″-difluoro-3α-(diphenylmethoxy)tropane ([125I]GA II 34) to identify the site of cross-linking and predict the binding pose relative to that of previously-examined cocaine photoaffinity analogs. Biochemical findings show that adduction of [125I]GA II 34 occurs at residues Asp79 or Leu80 in TM1, with molecular modeling supporting adduction to Leu80 and a pharmacophore pose in the central S1 site similar to that of cocaine and cocaine analogs. Substituted cysteine accessibility method protection analyses verified these findings, but identified some differences in structural stabilization relative to cocaine that may relate to BZT neurochemical outcomes. •Benztropine interaction with DAT was assessed using the photoaffinity ligand GA II 34.•Molecular modeling and peptide mapping identify adduction of GA II 34 to Leu80 of DAT.•Benztropinebased pharmacophores bind to DAT in the central substrate site.•Identification of the benztropine binding site reveals new insights for therapeutics targeting cocaine abuse.