Plasminogen Antibody #12657

Plasminogen is the inactive, proenzyme precursor to the serine protease plasmin that degrades fibrin within blood clots, promotes cell migration through proteolytic degradation of extracellular matrix proteins, and regulates angiogenesis and wound healing through activation of matrix metalloproteases (1-4). Inactive plasminogen is produced and secreted by liver cells and is found in the circulatory system and extracellular fluids (1). The plasminogen protein is composed of an amino terminal preactivation peptide followed by five kringle domains and a serine proteinase domain (5). The plasminogen zymogen binds to sites on the cell surface and is subsequently cleaved to release the active serine proteinase plasmin. Identified plasminogen cell surface receptors (including S100A10, enolase and PLGRKT) share carboxy-terminal lysine residues that interact with plasminogen kringle domains, resulting in cell surface localization of plasminogen (6-8). Cleavage of plasminogen can be catalyzed by a number of distinct enzymes, including tissue specific plasminogen activator (tPA), urokinase plasminogen activator (uPA), and kallikrein (1). An additional plasminogen cleavage product is the angiogenesis inhibitor angiostatin, which is derived from the first four kringle domains (9). A number of related angiogenesis inhibitors, derived from various parts of the plasminogen kringle region, have been shown to inhibit endothelial cell growth and proliferation (10). Mutations in the corresponding PLG gene have been linked to plasminogen deficiencies, characterized by decreased plasmin expression and ligneous conjunctivitis in some individuals (11).