LEKTI is a large multidomain serine protease inhibitor expressed in stratified epithelial tissue. It consists of 15 domains that are cleaved into smaller, functional fragments by the protease furin. Only two of these domains (2 and 15) contain 6 evenly spaced cysteines responsible for 3 intramolecular disulfide bonds characteristic of Kazal-type related inhibitors. The remaining domains contain 4 cysteines. These disulfide bonds force the molecule into a rigid conformation that enables the protein to interact with a target protease via an extended beta-sheet. All domains (excepting 1, 2 and 15) contain an arginine at P1, indicating trypsin-like proteases are the likely targets. In the epidermis, LEKTI is implicated in the regulation of desquamation via its ability to selectively inhibit KLK5, KLK7 and KLK14. Recombinant full length LEKTI inhibits the exogenous serine proteases trypsin, plasmin, subtilisin A, cathepsin G and human neutrophil elastase. Mutations in the SPINK5 gene result in Netherton syndrome, a disorder characterized by ichthyosis and specific immune system defects.