Converts the abundant, but inactive, zymogen plasminogen to plasmin by hydrolyzing a single Arg-Val bond in plasminogen. By controlling plasmin-mediated proteolysis, it plays an important role in tissue remodeling and degradation, in cell migration and many other physiopathological events. During oocyte activation, plays a role in cortical granule reaction in the zona reaction, which contributes to the block to polyspermy (By similarity).
