Proteolytic activation of tissue plasminogen activator by plasma and tissue enzymes.
Tissue kallikrein and factor Xa were found to activate tissue plasminogen activator (t-PA) at a rate comparable with that of plasmin. During the activation reaction, the single-chain molecule was converted into a two-chain form. A slight t-PA activating activity was also found in plasma kallikrein. Other activated coagulation factors, factor XIIa, factor XIa, factor IXa, factor VIIa, thrombin and activated protein C had no effect on t-PA activation. t-PA was also activated by a tissue kallikrein-like enzyme that was isolated from the culture medium of melanoma cells. These results indicate that tissue kallikrein and factor Xa may participate in the extrinsic pathway of human fibrinolysis.
D000818:Animals; D001779:Blood Coagulation Factors / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005170:Factor X / Q000378:metabolism*; D015951:Factor Xa; D007610:Kallikreins / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010179:Pancreas / Q000201:enzymology; D010960:Plasminogen Activators / Q000378:metabolism*; D013552:Swine
D001779:Blood Coagulation Factors; D046911:Macromolecular Substances; D005170:Factor X; D007610:Kallikreins; D010960:Plasminogen Activators; D015951:Factor Xa