Fibrinogen structure and fibrin clot assembly.

Fibrinogen is a complex multifunctional protein, which contains constitutive association sites (gammaXL, D:D, Da, Db) as well as cryptic sites that become exposed as a result of fibrinogen proteolysis by thrombin (EA, EB). Utilization of these sites by self-association (gammaXL or D:D) or by association with exposed complementary fibrin sites (Da:EA, Db:EB) produces an orderly process of molecular assembly to form linear and branched fibrils, concomitant with lateral fibril associations and factor XIIIa-mediated fibrin crosslinking that together result in the mature fibrin network.