Ready-to-use ELISA kits are available for the detection of GPR109B, an alias of the protein, hydroxycarboxylic acid receptor 3. The official gene symbol is HCAR3. The protein, with a mass of 44.5 kDa and length of 387 residues, is reported to be membrane-associated. It is a member of the G-protein coupled receptor 1 family and may be known by other names, including: nicotinic acid receptor 2, niacin receptor 2, GTP-binding protein, G-protein coupled receptor HM74B, G-protein coupled receptor HM74, and G-protein coupled receptor 109B, and GPR109B.