GPCR-G Protein-?-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 ?-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, ?-arrestin, and G protein. These super-complexes or "megaplexes" more readily form at receptors that interact strongly with ?-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 ?-arrestin. The formation of such megaplexes provides a potential physical basis for the newly appreciated sustained G protein signaling from internalized GPCRs.

SUBMITTER: Thomsen ARB 

PROVIDER: S-EPMC5418658 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature