free fatty acid receptors, member of the class A family of seven-transmembrane G protein-coupled receptors
This subfamily includes the free fatty acid receptors (FFARs) which bind free fatty acids (FFAs). They belong to the class A G-protein coupled receptors and are composed of three members, each encoded by a separate gene (FFAR1, FFAR2, and FFAR3). These genes and a fourth pseudogene, GPR42, are localized together on chromosome 19. FFAR1 is a receptor for medium- and long-chain FFAs, whereas FFAR2 and FFAR3 are receptors for short chain FFAs (SCFAs), which have different ligand affinities. FFAR1 directly mediates FFA stimulation of glucose-stimulated insulin secretion and also indirectly increases insulin secretion by enhancing the release of incretin. FFAR2 activation by SCFA suppresses adipose insulin signaling, which leads to the inhibition of fat accumulation in adipose tissue. FAAR3 is expressed in intestinal L cells, which produces glucagon-like peptide 1 (GLP-1) and peptide YY (PYY), suggesting that this receptor may be involved in energy homeostasis. FFARs are considered important components of the body's nutrient sensing mechanism, and therefore, these receptors are potential therapeutic targets for the treatment of metabolic disorders, such as type 2 diabetes and obesity.