Visualization and ligand-induced modulation of dopamine receptor dimerization at the single molecule level

• DOI: 10.1038/srep33233
• Publication Date: 2016-09-12T11:27:42Z
• Authors: Alina Tabor; Siegfried Weisenb...; Ashutosh Banerjee; Nirupam Purkayastha; Jonas M. Kaindl; Harald Hübner; Luxi Wei; Teja W. Grömer; Johannes Kornhuber; Nuska Tschammer; Nigel J. M. Birdsall; Gregory I. Mashanov; Vahid Sandoghdar; Peter Gmeiner
• Keywords: 0301 basic medicine; Receptors, Dopamine D2; -; CHO Cells; Ligands; Article; Kinetics; Protein Transport; 03 medical and health sciences; Cricetulus; Microscopy, Fluorescence; Medizinische Fakultät; Spiperone; Animals; Dopamine Antagonists; Humans; ddc:610; Protein Multimerization; Single-Cell Analysis; Protein Binding

AbstractG protein–coupled receptors (GPCRs), including dopamine receptors, represent a group of important pharmacological targets. An increased formation of dopamine receptor D2 homodimers has been suggested to be associated with the pathophysiology of schizophrenia. Selective labeling and ligand-induced modulation of dimerization may therefore allow the investigation of the pathophysiological role of these dimers. Using TIRF microscopy at the single molecule level, transient formation of homodimers of dopamine receptors in the membrane of stably transfected CHO cells has been observed. The equilibrium between dimers and monomers was modulated by the binding of ligands; whereas antagonists showed a ratio that was identical to that of unliganded receptors, agonist-bound D2 receptor-ligand complexes resulted in an increase in dimerization. Addition of bivalent D2 receptor ligands also resulted in a large increase in D2 receptor dimers. A physical interaction between the protomers was confirmed using high resolution cryogenic localization microscopy, with ca. 9 nm between the centers of mass.