Fibrinogen has a double function: yielding monomers that polymerize into fibrin and acting as a cofactor in platelet aggregation.
Involvement in disease
Defects in FGG are a cause of thrombophilia. Defects in FGG are a cause of congenital afibrinogenemia (CAFBN) [MIM:202400]. It is a rare autosomal recessive disorder characterized by complete absence of detectable fibrinogen.
Contains 1 fibrinogen C-terminal domain.
A long coiled coil structure formed by 3 polypeptide chains connects the central nodule to the C-terminal domains (distal nodules). The long C-terminal ends of the alpha chains fold back, contributing a fourth strand to the coiled coil structure.
Conversion of fibrinogen to fibrin is triggered by thrombin, which cleaves fibrinopeptides A and B from alpha and beta chains, and thus exposes the N-terminal polymerization sites responsible for the formation of the soft clot. The soft clot is converted into the hard clot by factor XIIIA which catalyzes the epsilon-(gamma-glutamyl)lysine cross-linking between gamma chains (stronger) and between alpha chains (weaker) of different monomers. Sulfation of C-terminal tyrosines increases affinity for thrombin.