title: GPCR-G Protein-β-Arrestin Super-Complex Mediates Sustained G Protein Signaling.
abstract: Classically, G protein-coupled receptor (GPCR) stimulation promotes G protein signaling at the plasma membrane, followed by rapid β-arrestin-mediated desensitization and receptor internalization into endosomes. However, it has been demonstrated that some GPCRs activate G proteins from within internalized cellular compartments, resulting in sustained signaling. We have used a variety of biochemical, biophysical, and cell-based methods to demonstrate the existence, functionality, and architecture of internalized receptor complexes composed of a single GPCR, β-arrestin, and G protein. These super-complexes or "megaplexes" more readily form at receptors that interact strongly with β-arrestins via a C-terminal tail containing clusters of serine/threonine phosphorylation sites. Single-particle electron microscopy analysis of negative-stained purified megaplexes reveals that a single receptor simultaneously binds through its core region with G protein and through its phosphorylated C-terminal tail with β-arrestin. The formation of such megaplexes provides a potential physical basis for the newly appreciated sustained G protein signaling from internalized GPCRs.
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors: Alex R B
authors: ARB
authors: Thomsen
authors: Department of Biochemistry and Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC H3C 3J7, Canada.
authors: Bianca
authors: B
authors: Plouffe
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA; Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
authors: Thomas J
authors: TJ
authors: Cahill
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors: Arun K
authors: AK
authors: Shukla
authors: Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors: Jeffrey T
authors: JT
authors: Tarrasch
authors: Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors: Annie M
authors: AM
authors: Dosey
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors: Alem W
authors: AW
authors: Kahsai
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors: Ryan T
authors: RT
authors: Strachan
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors: Biswaranjan
authors: B
authors: Pani
authors: Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA.
authors: Jacob P
authors: JP
authors: Mahoney
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors: Liyin
authors: L
authors: Huang
authors: Department of Biochemistry and Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC H3C 3J7, Canada.
authors: Billy
authors: B
authors: Breton
authors: Department of Biochemistry and Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC H3C 3J7, Canada.
authors: Franziska M
authors: FM
authors: Heydenreich
authors: Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
authors: Roger K
authors: RK
authors: Sunahara
authors: Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors: Georgios
authors: G
authors: Skiniotis
authors: Department of Biochemistry and Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC H3C 3J7, Canada. Electronic address: michel.bouvier@umontreal.ca.
authors: Michel
authors: M
authors: Bouvier
authors: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA; Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA; Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA. Electronic address: lefko001@receptor-biol.duke.edu.
authors: Robert J
authors: RJ
authors: Lefkowitz
mesh_terms: D060807:Bioluminescence Resonance Energy Transfer Techniques; D000242:Cyclic AMP / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D046912:Multiprotein Complexes; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D000071557:beta-Arrestins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D046912:Multiprotein Complexes; D043562:Receptors, G-Protein-Coupled; D000071557:beta-Arrestins; D000242:Cyclic AMP; D019205:GTP-Binding Protein alpha Subunits, Gs