GPCR-G Protein-β-Arrestin Super-Complex Mediates Sustained G Protein Signaling

Cell. 2016 Aug 11;166(4):907-919. doi: 10.1016/j.cell.2016.07.004. Epub 2016 Aug 4.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bioluminescence Resonance Energy Transfer Techniques
  • Cyclic AMP / metabolism
  • Endosomes / metabolism
  • GTP-Binding Protein alpha Subunits, Gs / metabolism
  • HEK293 Cells
  • Humans
  • Microscopy, Confocal
  • Microscopy, Electron
  • Multiprotein Complexes
  • Receptors, G-Protein-Coupled / agonists
  • Receptors, G-Protein-Coupled / antagonists & inhibitors
  • Receptors, G-Protein-Coupled / chemistry
  • Receptors, G-Protein-Coupled / metabolism*
  • Signal Transduction*
  • beta-Arrestins / chemistry
  • beta-Arrestins / metabolism*

Substances

  • Multiprotein Complexes
  • Receptors, G-Protein-Coupled
  • beta-Arrestins
  • Cyclic AMP
  • GTP-Binding Protein alpha Subunits, Gs