Serine protease. Activates thrombin by cleavage of prothrombin. Does not activate factor X. When injected into rats, causes thrombus formation, fibrinogen depletion, uncoagulable blood, decreased platelet count, inhibition of collagen-induced platelet aggregation, leukocyte infiltration in lungs, congestion and hemorrhage in renal glomeruli and necrosis in renal distal tubules. Causes increase in surface expression of ICAM-1 and E-selectin on human umbilical vein endothelial cells (HUVEC), but does not affect expression of VCAM-1, or the expression of mediators involved in coagulation and fibrinolysis systems (TF, vWF and t-PA). Increases expression of the platelet activation inhibitors NO and PGI2. Increases viability of HUVEC, and inhibits apoptosis. Activated by calcium ions. Inhibited by EDTA, activity is recovered by the addition of calcium ions, but not magnesium or zinc ions. Inhibited by PMSF. Homotetramer. Larval bristle. Eggs and larvae. Belongs to the calycin superfamily. Lipocalin family.