G-protein coupled receptor for medium and long chain saturated and unsaturated fatty acids that plays an important role in glucose homeostasis. Fatty acid binding increases glucose-stimulated insulin secretion, and may also enhance the secretion of glucagon-like peptide 1 (GLP-1). May also play a role in bone homeostasis; receptor signaling activates pathways that inhibit osteoclast differentiation (PubMed:23335512). Ligand binding leads to a conformation change that triggers signaling via G-proteins that activate phospholipase C, leading to an increase of the intracellular calcium concentration. Seems to act through a G(q) and G(i)-mediated pathway. Mediates the anti-inflammatory effects of omega-3 polyunsaturated fatty acids (PUFAs) via inhibition of NLRP3 inflammasome activation. Is also activated by synthetic agonists, such as AM-8182, AM-6331 and TAK-875 (fasiglifam). AM-8182 is a full agonist, while AM-6331 and TAK-875 (fasiglifam) are partial agonists that potentiate the activity of the endogenous ligands, such as alpha-linolenic acid and gamma-linolenic acid. Expressed in pancreatic islet beta cells (at protein level) (PubMed:16044321). Expressed in pancreatic islet beta cells. No visible phenotype at birth and during the following six weeks. Male mice tend to develop a slightly decreased glucose tolerance after 13 weeks of age, but this is not observed with female mice. Insulin secretion in response to glucose is unchanged in mutant mice, but it is not potentiated by fatty acids, contrary to what is observed with wild-type mice. On the other hand, wild-type and mutant mice display the same inhibition of the first phase of glucose-stimulated insulin secretion after prolonged exposure to fatty acids or exposure to a high-fat diet (PubMed:17395749 and PubMed:18559658). Compared to wild-type, mutant mice that are kept on a high-fat diet display a decrease of the second phase of glucose-stimulated insulin secretion (PubMed:18559658). Mutant mice do not display increased secretion of glucagon-like peptide 1 (GLP-1) in response to oral absorption of corn oil and display slightly increased blood glucose levels after oral absorption of corn oil (PubMed:23403053). Besides, mutant mice display decreased bone density (PubMed:23335512). Belongs to the G-protein coupled receptor 1 family.