Anti-APOA4 antibodies are used in the immunodetection of the protein apolipoprotein A4. In humans, the canonical protein has a reported length of 396 amino acid residues and a mass of 45.4 kDa. It has been described to be a secreted protein. It is notably expressed in the small intestine, kidney, and duodenum. A member of the Apolipoprotein A1/A4/E protein family, APOA4 is suspected to have a role in chylomicrons and VLDL secretion and catabolism. Post-translational modifications have been described, including phosphorylation. Synonyms for this target antigen include apo-AIV, apoA-IV, and apolipoprotein A-IV. APOA4 gene orthologs have been reported in the mouse, rat, bovine, frog, chimpanzee and chicken species.