Role of annexin II tetramer in plasminogen activation

The enzymatic cascade triggered by activation of plasminogen has been impli cated in a variety of normal and pathologic events, such as fibrinolysis, w ound healing, tissue remodeling, embryogenesis, and the invasion and spread of transformed tumor cells. Recent data established that the Ca2+- and pho spholipid-binding protein, annexin II heterotetramer (AIIt) binds tissue-ty pe plasminogen activator (tPA), plasminogen, and plasmin, and dramatically stimulates the tPA-dependent conversion of plasminogen to plasmin in vitro. Interestingly, the binding of plasmin to AIIt can inhibit the activity of the enzyme, suggesting that plasmin bound to the cell surface is regulated by AIIt. The existing experimental evidence suggests that AIIt is the key p hysiological receptor for plasminogen on the extracellular surface of endot helial cells. (Trends Cardiovasc Med 1999;9:92-102). (C) 1999, Elsevier Sci ence Inc.