Matriptase

Matriptase (MT-SP1, TADG-15, epithin, ST14, PRSS14) is an 80- to 90-kDa trypsin-like, multi-domain type II transmembrane serine protease. Matriptase is an endopeptidase that hydrolyses peptide bonds after arginine or lysine residues. These cleavage reactions, which take place on the cell surface, activate specific growth factors, G-protein-coupled receptors and other proteolytic enzymes. The cytoplasmic tail of matriptase is anchored to the actin cytoskeleton by filamin. Matriptase cleaves and activates protease activated receptor-2, pro-urokinase plasminogen activator, pro-hepatocyte growth factor, subtractive immunization M⁺ HEp3-associated 135 kDa protein (SIMA-135)/cub domain containing protein-1 (CDCP-1)/transmembrane and associated with Src kinases (Trask), and pro-prostasin. Matriptase is inhibited by insertion of the reactive site loop of Kunitz domain one of the hepatocyte growth factor activator inhibitor-1 (HAI-1), a Kunitz-type transmembrane serine protease inhibitor. The extracellular ectodomains of the matriptase/HAI-1 complex are then proteolytically shed from the cell surface.