Cleaves the alpha-chain at multiple sites and the beta-chain between 'Lys-53' and 'Lys-54' but not the gamma-chain of fibrinogen and therefore does not initiate the formation of the fibrin clot and does not cause the fibrinolysis directly. It does not cleave (activate) prothrombin and plasminogen but converts the inactive single chain urinary plasminogen activator (pro-urokinase) to the active two chain form. Activates coagulation factor VII (By similarity). Heterodimer; disulfide-linked. Heterodimer of a 50 kDa heavy and a 27 kDa light chain linked by a disulfide bond. Secreted as an inactive single-chain precursor and is then activated to a heterodimeric form. Liver and kidney. Proteolytic cleavage at Gly-23 or Met-27 can give rise to the 50 kDa heavy chain and cleavage at Arg-311 or Lys-317 can give rise to the 27 kDa light chain. The heavy chain can undergo further proteolytic cleavage at Arg-168 or Arg-169 to give rise to 2 inactive 26 kDa fragments and the light chain can undergo further proteolytic cleavage at Arg-478 to give rise to inactive 17 kDa and 8 kDa fragments. Belongs to the peptidase S1 family.