No abstract

Background:In mammals, extracellular proteolysis initiated by urokinase-type plasminogen activator (uPA) is associated with cell surfaces via the uPA-receptor uPAR. Results: Fish have two uPAs, one lacking the uPAR-binding domain, another having a uPAR-binding domain lacking two cysteines and a genuine uPAR-binding sequence. Conclusion:In fish, uPA-dependent proteolysis occurs without uPAR. Significance: Evolutionary studies provide a more comprehensive understanding of extracellular proteolysis.