Plasminogen binding to cell surfaces

Plasminogen binding to cell surfaces is mediated by their lysine binding sites, which interact with several cell membrane-associated components displaying carboxyl terminal lysine residues. The binding of plasminogen to some of these components induces changes in the Km of plasminogen-plasminogen activator interactions, promoting plasmin formation even in absence of fibrin. This process seems to be urokinase-type plasminogen activator receptor-independent. Although to a different extent, both cellular activities, promotion of plasmin formation and plasminogen binding capacity, can be modulated by proteolytic processes. The proteolytic system/s implicated in this processes remain to be fully identified. Cell-associated plasmin is slowly inhibited by alpha(2)-antiplasmin and thus, could mediate in several cellular functions such cell migration or proteolytic activation of some metalloproteases.