GPR109A is a high affinity receptor for nicotinic acid (niacin) and is a member of the nicotinic acid receptor family of G protein-coupled receptors (the other identified member being GPR109B). GPR109A is a Gi/o protein-coupled receptor with high affinity for nicotinic acid. In GPR109A knockout mice, the effects of niacin on both lipids and flushing are eliminated. Furthermore in arrestin beta 1 knockout mice, niacin's effect on flushing is greatly reduced while the lipid modifying effects are maintained. GPR109A is believed to be an important biomolecular target of niacin which is a widely prescribed drug for the treatment of dyslipidemia and to increase HDL cholesterol but whose therapeutic use is limited by flushing.