Real-time monitoring of receptor and G-protein interactions in living cells

Nat Methods. 2005 Mar;2(3):177-84. doi: 10.1038/nmeth743. Epub 2005 Feb 17.


G protein-coupled receptors (GPCRs) represent the largest family of proteins involved in signal transduction. Here we present a bioluminescence resonance energy transfer (BRET) assay that directly monitors in real time the early interactions between human GPCRs and their cognate G-protein subunits in living human cells. In addition to detecting basal precoupling of the receptors to Galpha-, Gbeta- and Ggamma-subunits, BRET measured very rapid ligand-induced increases in the interaction between receptor and Galphabetagamma-complexes (t(1/2) approximately 300 ms) followed by a slower (several minutes) decrease, reflecting receptor desensitization. The agonist-promoted increase in GPCR-Gbetagamma interaction was highly dependent on the identity of the Galpha-subunit present in the complex. Therefore, this G protein-activity biosensor provides a novel tool to directly probe the dynamics and selectivity of receptor-mediated, G-protein activation-deactivation cycles that could be advantageously used to identify ligands for orphan GPCRs.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cells, Cultured
  • Computer Systems
  • Fluorescence Resonance Energy Transfer / methods*
  • Fluorescent Dyes
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Kidney / metabolism*
  • Luminescent Measurements / methods*
  • Luminescent Proteins
  • Protein Interaction Mapping / methods*
  • Receptors, G-Protein-Coupled / metabolism*


  • Fluorescent Dyes
  • Luminescent Proteins
  • Receptors, G-Protein-Coupled
  • GTP-Binding Proteins