Anti-ARG1 antibodies are used in the immunodetection of the protein arginase 1. In humans, the canonical protein has a reported length of 322 amino acid residues and a mass of 34.7 kDa. Its subcellular localization is in the cytoplasm. Up to 3 different isoforms have been reported for this protein. It is notably expressed in the testis, spleen, liver, and bone marrow. A member of the Arginase protein family, Arg1 is reported to be a key element of the urea cycle converting L-arginine to urea and L-ornithine, which is further metabolized into metabolites proline and polyamides that drive collagen synthesis and bioenergetic pathways critical for cell proliferation, respectively; the urea cycle takes place primarily in the liver and, to a lesser extent, in the kidneys. Arg1 is also used as a cellular marker for characterizing myeloid-derived suppressor cells. Synonyms for this target antigen include liver-type arginase, type I arginase, and arginase, liver. ARG1 gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish and chimpanzee species.