Anti-APJ antibodies enable researchers to detect and measure the APJ antigen in biological samples. This target is a reported synonym of the APLNR gene, which encodes apelin receptor. This protein is known to function in angiogenesis and blood vessel development, among other biological roles. The human version of APJ has a canonical amino acid length of 380 residues and a protein mass of 42.7 kilodaltons. It is reported to be localized in the cell membrane of cells and notably expressed in many tissues, such as the cerebral cortex, tonsil, and caudate. Other names for this target antigen include AGTRL1 and APJR.