title: Individual protomers of a G protein-coupled receptor dimer integrate distinct functional modules.
abstract: Recent advances in proteomic technology reveal G-protein-coupled receptors (GPCRs) are organized as large, macromolecular protein complexes in cell membranes, adding a new layer of intricacy to GPCR signaling. We previously reported the α1D-adrenergic receptor (ADRA1D)-a key regulator of cardiovascular, urinary and CNS function-binds the syntrophin family of PDZ domain proteins (SNTA, SNTB1, and SNTB2) through a C-terminal PDZ ligand interaction, ensuring receptor plasma membrane localization and G-protein coupling. To assess the uniqueness of this novel GPCR complex, 23 human GPCRs containing Type I PDZ ligands were subjected to TAP/MS proteomic analysis. Syntrophins did not interact with any other GPCRs. Unexpectedly, a second PDZ domain protein, scribble (SCRIB), was detected in ADRA1D complexes. Biochemical, proteomic, and dynamic mass redistribution analyses indicate syntrophins and SCRIB compete for the PDZ ligand, simultaneously exist within an ADRA1D multimer, and impart divergent pharmacological properties to the complex. Our results reveal an unprecedented modular dimeric architecture for the ADRA1D in the cell membrane, providing unexpected opportunities for fine-tuning receptor function through novel protein interactionsin vivo, and for intervening in signal transduction with small molecules that can stabilize or disrupt unique GPCR:PDZ protein interfaces.
authors.affiliation: Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Camp
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Kyung-Soon
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Wacker-Mhyre
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Kountz
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Ji-Min
authors.initials: JM
authors.lastname: Park
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Dorathy-Ann
authors.initials: DA
authors.lastname: Harris
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Marianne
authors.initials: M
authors.lastname: Estrada
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Stewart
authors.affiliation: Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Wolf-Yadlin
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Hague
keywords: GPCR; PDZ domain; pharmacology; proteomics; scribble; syntrophin