Submitted on August 5, 2007
Accepted on February 15, 2008
Expression and function of the rat Vesicular Monoamine Transporter 2
Yoav Adam1, Robert H Edwards2, and Shimon Schuldiner1*
1 Alexander Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel
2 Neurology and Physiology, University of California School of Medicine, San Francisco, California, United States
* To whom correspondence should be addressed. E-mail: Shimon.Schuldiner{at}huji.ac.il.
The vesicular monoamine transporters (VMATs) are essential proteins, involved in the storage of monoamines in the central nervous system and in endocrine cells, in a process that involves exchange of 2H+ with one substrate molecule. The VMATs interact with various native substrates and clinically relevant drugs, and display the pharmacological profile of multidrug transporters. Vesicular transporters suffer from a lack of biochemical and structural data due to the difficulties in their expression. In this work we present the high -level expression of rat VMAT2 in a stable HEK293 cell line, generated using the resistance to the neurotoxin MPP+ conferred by the protein. In addition we describe novel procedures for the solubilization and purification of active protein, and its reconstitution into proteoliposomes. The partially purified protein in detergent binds the inhibitor tetrabenazine, and after reconstitution, displays high levels of 
µH+ driven electrogenic transport of serotonin. The reconstituted purified rVMAT2, has wild type affinity for serotonin, and its turnover rate is ~0.4 substrate molecules per second.
