Serine-type endopeptidase with a dual trypsin-like and chymotrypsin-like substrate specificity. May activate/inactivate the proteinase-activated receptors F2R, F2RL1 and F2RL3 and other kallikreins including KLK1, KLK3, KLK5 and KLK11. May function in seminal clot liquefaction through direct cleavage of the semenogelin SEMG1 and SEMG2 and activation of KLK3. May function through desmoglein DSG1 cleavage in epidermal desquamation a process by which the most superficial corneocytes are shed from the skin surface. May be involved in several aspects of tumor progression including growth, invasion and angiogenesis (By similarity). Inhibited by SERPINA1, SERPINC1, SERPINE1, SERPINF2, aprotinin, soybean, trypsin inhibitor and leupeptin. Inhibited by serine protease inhibitor SPINK5. Has an autoproteolytic activity which may have a regulatory effect. Activated by citrate and inhibited by zinc and to a lower extent by manganese (By similarity). Proteolytic cleavage of the activation peptide produces the active enzyme. Belongs to the peptidase S1 family. Kallikrein subfamily.