title: Regulation of G-protein coupled receptor traffic by an evolutionary conserved hydrophobic signal.
abstract: Plasma membrane (PM) expression of G-protein coupled receptors (GPCRs) is required for activation by extracellular ligands; however, mechanisms that regulate PM expression of GPCRs are poorly understood. For some GPCRs, such as alpha2c-adrenergic receptors (alpha(2c)-ARs), heterologous expression in non-native cells results in limited PM expression and extensive endoplasmic reticulum (ER) retention. Recently, ER export/retentions signals have been proposed to regulate cellular trafficking of several GPCRs. By utilizing a chimeric alpha(2a)/alpha(2c)-AR strategy, we identified an evolutionary conserved hydrophobic sequence (ALAAALAAAAA) in the extracellular amino terminal region that is responsible in part for alpha(2c)-AR subtype-specific trafficking. To our knowledge, this is the first luminal ER retention signal reported for a GPCR. Removal or disruption of the ER retention signal dramatically increased PM expression and decreased ER retention. Conversely, transplantation of this hydrophobic sequence into alpha(2a)-ARs reduced their PM expression and increased ER retention. This evolutionary conserved hydrophobic trafficking signal within alpha(2c)-ARs serves as a regulator of GPCR trafficking.
authors.affiliation: Department of Anesthesia, Stanford University School of Medicine, 300 Pasteur Drive, Grant Building S286, Stanford, CA 94305, USA. timangel@stanford.edu
authors.forename: Tim
authors.initials: T
authors.lastname: Angelotti
authors.forename: David
authors.initials: D
authors.lastname: Daunt
authors.forename: Olga G
authors.initials: OG
authors.lastname: Shcherbakova
authors.forename: Brian
authors.initials: B
authors.lastname: Kobilka
authors.forename: Carl M
authors.initials: CM
authors.lastname: Hurt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019143:Evolution, Molecular; D057927:Hydrophobic and Hydrophilic Interactions; D016716:PC12 Cells; D021382:Protein Sorting Signals; D021381:Protein Transport; D051381:Rats; D018341:Receptors, Adrenergic, alpha-2 / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D021382:Protein Sorting Signals; D018341:Receptors, Adrenergic, alpha-2; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins