title: Quantitative assessment of beta 1- and beta 2-adrenergic receptor homo- and heterodimerization by bioluminescence resonance energy transfer.
abstract: Quantitative bioluminescence resonance energy transfer (BRET) analysis was applied to the study of beta(1)- and beta(2)-adrenergic receptor homo- and heterodimerization. To assess the relative affinity between each of the protomers, BRET saturation experiments were carried out in HEK-293T cells. beta(1)- and beta(2)-adrenergic receptors were found to have similar propensity to engage in homo- and heterotropic interactions suggesting that, at equivalent expression levels of the two receptor subtypes, an equal proportion of homo- and heterodimers would form. Analysis of the data also revealed that, at equimolar expression levels of energy donor and acceptor, more than 80% of the receptor molecules exist as dimers and that this high incidence of receptor dimerization is insensitive to receptor density for expression levels varying between 1.4 and 26.9 pmol of receptor/mg of membrane protein. Taken together, these results indicate that most of the receptors expressed in cells exist as constitutive dimers and that, at least in undifferentiated fibroblasts, the proportion of homo- and heterodimers between the closely related beta(1)- and beta(2)-adrenergic receptors is determined by their relative levels of expression.
authors.affiliation: Département de Biochimie and Groupe de Recherche sur le Système Nerveux Autonome, Université de Montréal, Montréal, Quebec H3C 3J7, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mercier
authors.forename: Ali
authors.initials: A
authors.lastname: Salahpour
authors.forename: Stéphane
authors.initials: S
authors.lastname: Angers
authors.forename: Andreas
authors.initials: A
authors.lastname: Breit
authors.forename: Michel
authors.initials: M
authors.lastname: Bouvier
mesh_terms: D002460:Cell Line; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006801:Humans; D008163:Luminescent Measurements; D020836:Protein Structure, Quaternary; D011869:Radioligand Assay; D018342:Receptors, Adrenergic, beta-1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D011993:Recombinant Fusion Proteins