Serine protease that cleaves the inactive precursor plasminogen at a specific Arg-Val peptide bond, converting it into active plasmin. Secreted as an inactive zymogen, it is recruited and activated at the cell surface through interaction with the urokinase plasminogen activator receptor (uPAR). Cell-surface activation enables localized, plasmin-dependent pericellular proteolysis, regulating extracellular matrix degradation in cell migration and tissue remodeling. Also contributes to fibrinolysis and blood clot clearance by promoting plasmin generation (By similarity).
Post-translational: Phosphorylation of Ser-158 and Ser-323 abolishes proadhesive ability but does not interfere with receptor binding. Produced as an inactive single-chain protein (pro-uPA or sc-uPA), is processed into the active disulfide-linked two-chain form of PLAU/uPA by a proteolytic event mediated, at least, by TMPRSS4.