Description
BrainSpecific Serine Protease 4 (BSSP4) is a serine protease that preferentially cleaves the synthetic substrate HDLeuThrArgpNA compared to tosylGlyProArgpNA. BSSP4 is expressed abundantly in the epithelial cells of the airways, including trachea, esophagus and fetal lung, but scarce in adult lung and expressed at low levels in placenta, pancreas, prostate and thyroid gland. BSSP4 belongs to the peptidase S1 family and related to trypsin, referentially hydrolyzing substrates after arginine and lysine residues. However, BSSP4 is less susceptible to inhibition by common trypsin inhibitors such as aprotinin, alpha1antitrypsin and secretory leukocyte protease inhibitor. BSSP4 efficiently converts prourokinase type plasminogen activator to its mature, active form