Anti-GPR109B antibodies are protein reagents that detect specific antigens. The GPR109B antigen is another term for the human protein hydroxycarboxylic acid receptor 3, encoded by the HCAR3 gene. The protein is a known receptor for 3-OH-octanoid acid mediates a negative feedback regulation of adipocyte lipolysis to counteract prolipolytic influences under conditions of physiological or pathological increases in beta-oxidation rates. Canonically, it has an amino acid length of 387 residues and a mass of 44.5 kilodaltons. Its subcellular localization is in the cell membrane and it is expressed in soft tissue, nasopharynx, lymph node, lung, and bone marrow. The GPR109B protein is a member of the G-protein coupled receptor 1 protein family. Other alias names for GPR109B include HCA3.