Fibrin & PLAU

Fibrin (Factor Ia) is a fibrous, non-globular protein involved in the clotting of blood. It is formed by the action of the protease thrombin on fibrinogen which causes it to polymerize. And the polymerized fibrin together with platelets forms a hemostatic plug or clot over a wound site.

This gene encodes a serine protease involved in degradation of the extracellular matrix and possibly tumor cell migration and proliferation. A specific polymorphism in this gene may be associated with late-onset Alzheimers disease and also with decreased affinity for fibrin-binding. This protein converts plasminogen to plasmin by specific cleavage of an Arg-Val bond in plasminogen. Plasmin in turn cleaves this protein at a Lys-Ile bond to form a two-chain derivative in which a single disulfide bond connects the amino-terminal A-chain to the catalytically active, carboxy-terminal B-chain. This two-chain derivative is also called HMW-uPA (high molecular weight uPA). HMW-uPA can be further processed into LMW-uPA (low molecular weight uPA) by cleavage of chain A into a short chain A (A1) and an amino-terminal fragment. LMW-uPA is proteolytically active but does not bind to the uPA receptor. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.