Distinct conformational changes in beta-arrestin report biased agonism at seven-transmembrane receptors.

Published

Journal Article

Beta-arrestins critically regulate G protein-coupled receptors (GPCRs), also known as seven-transmembrane receptors (7TMRs), both by inhibiting classical G protein signaling and by initiating distinct beta-arrestin-mediated signaling. The recent discovery of beta-arrestin-biased ligands and receptor mutants has allowed characterization of these independent "G protein-mediated" and "beta-arrestin-mediated" signaling mechanisms of 7TMRs. However, the molecular mechanisms underlying the dual functions of beta-arrestins remain unclear. Here, using an intramolecular BRET (bioluminescence resonance energy transfer)-based biosensor of beta-arrestin 2 and a combination of biased ligands and/or biased mutants of three different 7TMRs, we provide evidence that beta-arrestin can adopt multiple "active" conformations. Surprisingly, phosphorylation-deficient mutants of the receptors are also capable of directing similar conformational changes in beta-arrestin as is the wild-type receptor. This indicates that distinct receptor conformations induced and/or stabilized by different ligands can promote distinct and functionally specific conformations in beta-arrestin even in the absence of receptor phosphorylation. Our data thus highlight another interesting aspect of 7TMR signaling--i.e., functionally specific receptor conformations can be translated to downstream effectors such as beta-arrestins, thereby governing their functional specificity.

Full Text

Duke Authors

Cited Authors

  • Shukla, AK; Violin, JD; Whalen, EJ; Gesty-Palmer, D; Shenoy, SK; Lefkowitz, RJ

Published Date

  • July 22, 2008

Published In

Volume / Issue

  • 105 / 29

Start / End Page

  • 9988 - 9993

PubMed ID

  • 18621717

Pubmed Central ID

  • 18621717

Electronic International Standard Serial Number (EISSN)

  • 1091-6490

Digital Object Identifier (DOI)

  • 10.1073/pnas.0804246105

Language

  • eng

Conference Location

  • United States