PMID: 29695780

Authors:

Ho JD, Chau B, Rodgers L, Lu F, Wilbur KL, Otto KA, Chen Y, Song M, Riley JP, Yang HC, Reynolds NA, Kahl SD, Lewis AP, Groshong C, Madsen RE, Conners K, Lineswala JP, Gheyi T, Saflor MD, Lee MR, Benach J, Baker KA, Montrose-Rafizadeh C, Genin MJ, Miller AR, Hamdouchi C

Title:

Structural basis for GPR40 allosteric agonism and incretin stimulation.

Journal:

Nat Commun. 2018 Apr 25;9(1):1645. doi: 10.1038/s41467-017-01240-w.

Abstract:

Activation of free fatty acid receptor 1 (GPR40) by synthetic partial and full agonists occur via distinct allosteric sites. A crystal structure of GPR40-TAK-875 complex revealed the allosteric site for the partial agonist. Here we report the 2.76-A crystal structure of human GPR40 in complex with a synthetic full agonist, compound 1, bound to the second allosteric site. Unlike TAK-875, which acts as a Galphaq-coupled partial agonist, compound 1 is a dual Galphaq and Galphas-coupled full agonist. compound 1 binds in the lipid-rich region of the receptor near intracellular loop 2 (ICL2), in which the stabilization of ICL2 by the ligand is likely the primary mechanism for the enhanced G protein activities. The endogenous free fatty acid (FFA), gamma-linolenic acid, can be computationally modeled in this site. Both gamma-linolenic acid and compound 1 exhibit positive cooperativity with TAK-875, suggesting that this site could also serve as a FFA binding site.