Anti-JH antibodies are protein reagents that detect specific antigens. The JH antigen is another term for the human protein hemojuvelin BMP co-receptor, encoded by the HJV gene. The protein is known to act as a bone morphogenetic protein (BMP) coreceptor. Canonically, it has an amino acid length of 426 residues and a mass of 45.1 kilodaltons. Its subcellular localization is in the cell membrane. The JH protein is a member of the Repulsive guidance molecule (RGM) protein family.