Anti-serine peptidase inhibitor Kazal type 5 antibodies are used for the immunodetection of the protein encoded by the SPINK5 gene. In humans, the canonical protein has a reported length of 1064 amino acid residues and a mass of 120.7 kDa. It is known to be a secreted protein. Alternative splicing is reported to yield 3 different isoforms for this protein. It is reported to be highly expressed in the thymus and stratum corneum. It is noted to be involved in cell differentiation and nervous system development. Post-translational modifications have been described, including protein cleavage. The gene encoding this protein is implicated in Netherton syndrome. Other names for this target antigen include LETKI, NETS, NS, VAKTI, serine protease inhibitor Kazal-type 5, and LEKTI. Gene orthologs have been identified in the mouse, rat, bovine, chimpanzee and chicken species.