title: Human kallikrein 4: enzymatic activity, inhibition, and degradation of extracellular matrix proteins.
abstract: Human kallikrein 4 (hK4) is a member of the expanded family of human kallikreins, a group of 15 secreted proteases. While this protein has been associated with ovarian and prostate cancer prognosis, only limited functional information exists. Therefore, we have undertaken an investigation of its enzymatic properties regarding substrate preference, degradation of extracellular matrix proteins, and its inhibition by various inhibitors. We successfully expressed and purified active recombinant hK4 from supernatants of the Pichia pastoris expression system. This enzyme seems to cleave more efficiently after Arg compared to Lys at the P1 position and exhibits modest specificity for amino acids at positions P2 and P3. hK4 forms complexes with alpha1-antitrypsin, alpha2-antiplasmin and alpha2-macroglobulin. The protease mediates limited degradation of extracellular matrix proteins such as collagen I and IV, and more efficient degradation of the alpha-chain of fibrinogen. The cleavage of extracellular matrix proteins by hK4 suggests that this enzyme may play a role in tissue remodeling and cancer metastasis.
authors.affiliation: Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, and Department of Laboratory Medicine and Pathobiology, University of Toronto, 100 College Street, Toronto M5G 1L5, ON, Canada.
authors.forename: Chistina V
authors.initials: CV
authors.lastname: Obiezu
authors.forename: Iacovos P
authors.initials: IP
authors.lastname: Michael
authors.forename: Michael A
authors.initials: MA
authors.lastname: Levesque
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
mesh_terms: D003001:Cloning, Molecular / Q000379:methods; D016326:Extracellular Matrix Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D007610:Kallikreins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins; D013379:Substrate Specificity; D000515:alpha 1-Antitrypsin / Q000378:metabolism; D000979:alpha-2-Antiplasmin / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism
chemical_list: D016326:Extracellular Matrix Proteins; D011994:Recombinant Proteins; D000515:alpha 1-Antitrypsin; D000979:alpha-2-Antiplasmin; D000511:alpha-Macroglobulins; D007610:Kallikreins; C120801:kallikrein 4