What is the structure and function of plasminogen?
Plasminogen is the inactive precursor of plasmin, a potent serine protease involved in the dissolution of fibrin clots in blood. Human plasminogen is a single-chain glycoprotein with a molecular mass of 92 kDa. The N-terminal portion of the plasminogen molecule consists of five kringle domains with the capacity to bind to fibrin. The kringles control the ability of plg to adopt different conformations. The protease domain resembles that of the other serine proteases and contains the active site His, Asp, Ser. The region also contains Ala, which appears to be essential for the normal function of plasminogen, since mutation from Ala601 to Thr601 (alanine to threonine point mutation) leads to an increased risk of thrombosis.