Identification and Pharmacological Characterization of Multiple Allosteric Binding Sites on the Free Fatty Acid 1 Receptor

Free fatty acid receptor 1 (FFA1 or GPR40), activated by medium- and long-chain fatty acids, amplifies glucose-stimulated insulin secretion, making it a promising target for type 2 diabetes. Radioligand studies revealed distinct binding sites for partial and full agonists, with full agonists showing positive cooperativity. Functional assays demonstrated positive cooperativity between agonists and varying interactions with the endogenous fatty acid DHA. These findings suggest three allosterically linked binding sites on FFA1, with activation influenced by key arginine residues. Potent ligands with strong cooperativity hold significant therapeutic potential.