The hyaluronan-binding protein 2 (HABP2), also designated plasma hyaluronan-binding protein (PHBP) or factor VII-activating protease, belongs to the peptidase S1 family and contains three EGF-like domains, one kringle domain and one peptidase S1 domain. HABP2 is a heterodimer that contains a heavy chain of 50 kDa and a light chain of 27 kDa, which are linked by a disulfide bond. HABP2 is ubiquitously expressed and acts as a serine protease with fibrinogen and fibronectin being the major substrates. HABP2 has been shown to cleave the alpha-chain at multiple sites and the beta-chain between lysine53 and lysine54, but not the gamma-chain of fibrinogen. Overexpression of HABP2 has been shown to occur in lung adenocarcinomas and may be a useful biomarker for that type of cancer.
