title: Ligand sensitivity in dimeric associations of the serotonin 5HT2c receptor.
abstract: G-protein-coupled receptors (GPCRs) respond to external stimuli by activating heterotrimeric G proteins inside the cell. There is increasing evidence that many GPCRs exist as dimers or higher oligomers, but the biochemical nature of such dimers and what roles they have, if any, in signal transduction remains unclear. We conducted a comprehensive study of dimerization of the 5HT2c serotonin receptor using disulphide-trapping experiments. We found a dimer interface between transmembrane (TM) helices IV and V that is markedly sensitive to the state of receptor activation. This dimer seems to be quasisymmetrical in interfacial geometry and asymmetrical in its association with its cognate G alpha protein. We also found a second interface at TM I helices, which is insensitive to the state of activation.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
authors.forename: Filippo
authors.initials: F
authors.lastname: Mancia
authors.forename: Zahra
authors.initials: Z
authors.lastname: Assur
authors.forename: Ariel G
authors.initials: AG
authors.lastname: Herman
authors.forename: Risa
authors.initials: R
authors.lastname: Siegel
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Hendrickson
mesh_terms: D002460:Cell Line; D003545:Cysteine / Q000235:genetics; D019281:Dimerization; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008024:Ligands; D008958:Models, Molecular; D016296:Mutagenesis; D017434:Protein Structure, Tertiary; D044405:Receptor, Serotonin, 5-HT2C / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D008024:Ligands; D044405:Receptor, Serotonin, 5-HT2C; D003545:Cysteine