title: Instability of a class a G protein-coupled receptor oligomer interface.
abstract: The quaternary structure of G protein-coupled receptors (GPCRs) can influence their trafficking and ability to transduce signals. GPCR oligomers are generally portrayed as long-lived entities, although the stability of these complexes has not been studied. Here we show that D2 dopamine receptor protomers interact transiently at a specific oligomer interface. Selective immobilization of cyan fluorescent protein-D2 receptors (C-D2Rs) in the plasma membrane failed to completely immobilize coexpressed D2-venus receptors (D2R-Vs), suggesting that the two did not form stable oligomers with each other. Oxidative cross-linking stabilized C-D2R-D2R-V oligomers such that immobilization of C-D2R also immobilized D2R-V. This stabilization required the presence in both C-D2R and D2R-V of a cysteine residue in transmembrane domain 4 (TM4), a region identified as a putative oligomer interface in these and other class A GPCRs. These results suggest that the interaction of D2 receptor protomers at TM4 is transient unless stabilized and that the quaternary structure of these receptors may thus be subject to physiological or pharmacological regulation.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, 30912-2300, USA.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Fonseca
authors.forename: Nevin A
authors.initials: NA
authors.lastname: Lambert
mesh_terms: D000906:Antibodies / Q000737:chemistry; D001426:Bacterial Proteins / Q000235:genetics; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D008163:Luminescent Measurements; D008164:Luminescent Proteins / Q000235:genetics; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D055503:Protein Multimerization; D021381:Protein Transport; D017448:Receptors, Dopamine D2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D008164:Luminescent Proteins; D017448:Receptors, Dopamine D2; D011993:Recombinant Fusion Proteins; C527701:enhanced cyan fluorescent protein; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins