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Affinity labeling the dopamine transporter ligand binding site.
Roxanne A Vaughan1, M Laura Parnas, Jon D Gaffaney
1Department of Biochemistry and Molecular Biology, University of North Dakota, School of Medicine and Health Sciences, 501 N. Columbia Road, Grand Forks, ND 58203, USA. rvaughan@medicine.nodak.edu
Journal of Neuroscience Methods
|March 15, 2005
Summary
Photoaffinity labeling identified cocaine-binding sites on the dopamine transporter (DAT). This method precisely located ligand interactions within the DAT protein structure.
Area of Science:
- Neuroscience
- Biochemistry
- Pharmacology
Background:
- The dopamine transporter (DAT) plays a crucial role in regulating dopaminergic neurotransmission.
- Identifying the specific binding sites on DAT is essential for understanding its function and for drug development.
Purpose of the Study:
- To identify the cocaine-binding site on the dopamine transporter (DAT) using photoaffinity labeling.
- To precisely localize the regions within DAT that interact with various ligands.
Main Methods:
- Photoaffinity labeling of DAT with radioactive and non-radioactive cocaine analogs.
- Enzymatic and chemical cleavage of photolabeled DAT.
- Analysis of labeled peptides using immunoprecipitation, gel electrophoresis, autoradiography, and reverse-phase HPLC.
- Mass spectrometry (MALDI and nanoelectrospray) for peptide identification.
Main Results:
- Identified specific regions within the DAT primary sequence that interact with ligands.
- Localized labeled fragments as small as 4 kDa.
- Confirmed DAT sequence in labeled peptides using mass spectrometry.
- Discovered two distinct regions in DAT interacting with diverse irreversible ligands.
Conclusions:
- Photoaffinity labeling is an effective method for mapping ligand-binding sites on DAT.
- Two distinct regions within DAT are implicated in ligand binding, suggesting their importance in forming the binding pocket.