Structural basis for the cooperative allosteric activation of the free fatty acid receptor GPR40

Nat Struct Mol Biol. 2017 Jul;24(7):570-577. doi: 10.1038/nsmb.3417. Epub 2017 Jun 5.


Clinical studies indicate that partial agonists of the G-protein-coupled, free fatty acid receptor 1 GPR40 enhance glucose-dependent insulin secretion and represent a potential mechanism for the treatment of type 2 diabetes mellitus. Full allosteric agonists (AgoPAMs) of GPR40 bind to a site distinct from partial agonists and can provide additional efficacy. We report the 3.2-Å crystal structure of human GPR40 (hGPR40) in complex with both the partial agonist MK-8666 and an AgoPAM, which exposes a novel lipid-facing AgoPAM-binding pocket outside the transmembrane helical bundle. Comparison with an additional 2.2-Å structure of the hGPR40-MK-8666 binary complex reveals an induced-fit conformational coupling between the partial agonist and AgoPAM binding sites, involving rearrangements of the transmembrane helices 4 and 5 (TM4 and TM5) and transition of the intracellular loop 2 (ICL2) into a short helix. These conformational changes likely prime GPR40 to a more active-like state and explain the binding cooperativity between these ligands.

MeSH terms

  • Allosteric Regulation
  • Binding Sites
  • Crystallography, X-Ray
  • Humans
  • Models, Molecular
  • Protein Binding
  • Protein Conformation
  • Receptors, G-Protein-Coupled / agonists*
  • Receptors, G-Protein-Coupled / chemistry*


  • FFAR1 protein, human
  • Receptors, G-Protein-Coupled