Annexin II and regulation of cell surface fibrinolysis.

The regulated function of the fibrinolytic system is fundamental to the solubilization of fibrin-containing thrombi and to a number of other biologic processes. In recent years, several receptors, which serve to localize proteolytic activity on the cell surface, have been identified on endothelial cells, blood cells, neuronal cells, and tumor cells. One such receptor is annexin II, a calcium- and phospholipid-binding protein that serves as a profibrinolytic co-receptor for tissue plasminogen activator and plasminogen on endothelial cells. Accumulating evidence suggests that impaired cell surface fibrinolytic assembly could lead to progressive atherothrombotic disease. In addition, dysregulation of annexin II expression in acute promyelocytic leukemia is an important mechanism for the bleeding diathesis associated with this malignancy.