Background：TMPRSS11F is a type-II transmembrane protease, similar to hepsin （TMPRSS1）. TMPRSS11F is a member of a larger family of membrane attached serine proteases, a poorly defined group that includes TMPRSS11A, B, C, D, E, F, Hepsin, Corin, Matriptase-1, 2 and 3. TMPRSS11F has a domain structure of an aminoterminal cytoplasmic domain, followed by a transmembrane domain, a SEA domain （Sea urchin sperm protein, Enterokinase, Agrin）, a short spacer, then the trypsin-like serine protease domain. The SEA domain is thought to play a role in carbohydrate binding in the analogous protein sequences where it is found, but its role in TMPRSS11F is unclear. The cleavage of the Arg206-Ile207 bond is thought to liberate the catalytic domain.
