Buried ionizable networks are an ancient hallmark of G protein-coupled receptor activation

Daniel G. Isom, Henrik G. Dohlman

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Seven-transmembrane receptors (7TMRs) have evolved in prokaryotes and eukaryotes over hundreds of millions of years. Comparative structural analysis suggests that these receptors may share a remote evolutionary origin, despite their lack of sequence similarity. Here we used structure-based computations to compare 221 7TMRs from all domains of life. Unexpectedly, we discovered that these receptors contain spatially conserved networks of buried ionizable groups. In microbial 7TMRs these networks are used to pump ions across the cell membrane in response to light. In animal 7TMRs, which include light- and ligand-activated G protein-coupled receptors (GPCRs), homologous networks were found to be characteristic of activated receptor conformations. These networks are likely relevant to receptor function because they connect the ligand-binding pocket of the receptor to the nucleotide-binding pocket of the G protein. We propose that agonist and G protein binding facilitate the formation of these electrostatic networks and promote important structural rearrangements such as the displacement of transmembrane helix-6. We anticipate that robust classification of activated GPCR structures will aid the identification of ligands that target activated GPCR structural states.

Original languageEnglish (US)
Pages (from-to)5702-5707
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number18
StatePublished - May 5 2015
Externally publishedYes


  • 7-Transmembrane receptor
  • Buried charge
  • G protein-coupled receptor
  • Molecular evolution
  • Structural bioinformatics

ASJC Scopus subject areas

  • General


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