Anti-ISG15 ubiquitin like modifier antibodies are used for the immunodetection of the protein encoded by the ISG15 gene. In humans, the canonical protein has a reported length of 165 amino acid residues and a mass of 17.9 kDa. Its subcellular localization is in the cytoplasm and is secreted. It is notably expressed in lymphoid cells, striated and smooth muscle, several epithelia and neurons. It is reported to be a ubiquitin-like protein, which plays a key role in the innate immune response to viral infection either via its conjugation to a target protein (ISGylation) or via its action as a free or unconjugated protein. Post-translational modifications have been described, including protein cleavage. The gene encoding this protein is implicated in Immunodeficiency. Other names for this target antigen include IFI15, IMD38, IP17, UCRP, hUCRP, and G1P2. Gene orthologs have been identified in the mouse, rat, bovine and chimpanzee species.