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TheScientificWorldJOURNAL
Volume 7 (2007), Pages 48-57
http://dx.doi.org/10.1100/tsw.2007.197
Mini-Review Article

Basic Concepts in G-Protein-Coupled Receptor Homo- and Heterodimerization

1Institut d'Investigació Biomèca August Pi I Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), and Departament de Bioquímica i Biologia Molecular. Universitat de Barcelona. Diagonal 645, 08028 Barcelona, Catalonia, Spain
2National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, U.S. Department of Health and Human Services, Baltimore, MD 21224, USA

Received 11 June 2007; Revised 3 July 2007; Accepted 9 July 2007

Academic Editors: D. Shurtleff and S. Ferre

Copyright © 2007 Rafael Franco et al.

Abstract

Until recently, heptahelical G-protein-coupled receptors (GPCRs) were considered to be expressed as monomers on the cell surface of neuronal and non-neuronal cells. It is now becoming evident that this view must be overtly changed since these receptors can form homodimers, heterodimers, and higher-order oligomers on the plasma membrane. Here we discuss some of the basics and some new concepts of receptor homo- and heteromerization. Dimers-oligomers modify pharmacology, trafficking, and signaling of receptors. First of all, GPCR dimers must be considered as the main molecules that are targeted by neurotransmitters or by drugs. Thus, binding data must be fitted to dimer-based models. In these models, it is considered that the conformational changes transmitted within the dimer molecule lead to cooperativity. Cooperativity must be taken into account in the binding of agonists-antagonists-drugs and also in the binding of the so-called allosteric modulators. Cooperativity results from the intramolecular cross-talk in the homodimer. As an intramolecular cross-talk in the heterodimer, the binding of one neurotransmitter to one receptor often affects the binding of the second neurotransmitter to the partner receptor. Coactivation of the two receptors in a heterodimer can change completely the signaling pathway triggered by the neurotransmitter as well as the trafficking of the receptors. Heterodimer-specific drugs or dual drugs able to activate the two receptors in the heterodimer simultaneously emerge as novel and promising drugs for a variety of central nervous system (CNS) therapeutic applications.