GPR109A is a Gi/Go protein-coupled receptor of the A11 subfamily of GPCR receptors. It is both a receptor for nicotinate (niacin or vitamine B3) and mediates the lipid-lowering actions of the vitamin, as well as it is a receptor for butyrate in the colon. Nicotinic acid and its derivative, e.g., Acipimox, have been used clinically in the treatment for hyperlipidemia. These substances are known to lower elevated plasma concentration of low-density lipoprotein (LDL), intermediate-density lipoprotein, very low-density lipoprotein (VLDL), triglycerides (TG), and lipoprotein Lp(a), and also increase plasma high density lipoprotein (HDL) concentrations, resulting in an improvement of mortality rate against coronary artery disease. GPR109A expression in colon is induced by gut microbiota and is downregulated in colon cancer. GPR109A in immune cells plays a nonredundant function in niacin-mediated suppression of inflammation and atherosclerosis.
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 N. Singh et al. Activation of Gpr109a, receptor for niacin and the commensal metabolite butyrate, suppresses colonic inflammation and carcinogenesis. Immunity. 2014, 40, 128-139.