PLASMINOGEN BINDING TO CELL-SURFACES

Plasminogen binding to cell surfaces is mediated by their lysine bindi ng sites, which interact with several cell membrane-associated compone nts displaying carboxyl terminal lysine residues. The binding of plasm inogen to some of these components induces changes in the Km of plasmi nogen-plasminogen activator interactions, promoting plasmin formation even in absence of fibrin. This process seems to be urokinase-type pla sminogen activator receptor-independent. Although to a different exten t, both cellular activities, promotion of plasmin formation and plasmi nogen 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)-an tiplasmin and thus, could mediate in several cellular functions such c ell migration or proteolytic activation of some metalloproteases.