Fibrinogen (Pg, Fn & Vwf Depleted) (FGA) Active Protein

The protein encoded by this gene is the alpha component of fibrinogen, a blood-borne glycoprotein comprised of three pairs of nonidentical polypeptide chains. Following vascular injury, fibrinogen is cleaved by thrombin to form fibrin which is the most abundant component of blood clots. In addition, various cleavage products of fibrinogen and fibrin regulate cell adhesion and spreading, display vasoconstrictor and chemotactic activities, and are mitogens for several cell types. Mutations in this gene lead to several disorders, including dysfibrinogenemia, hypofibrinogenemia, afibrinogenemia and renal amyloidosis. Alternative splicing results in two isoforms which vary in the carboxy-terminus. [provided by RefSeq, Jul 2008]

FGA: Fibrinogen has a double function: yielding monomers that polymerize into fibrin and acting as a cofactor in platelet aggregation. Defects in FGA are a cause of congenital afibrinogenemia (CAFBN). This is a rare autosomal recessive disorder characterized by bleeding that varies from mild to severe and by complete absence or extremely low levels of plasma and platelet fibrinogen. The majority of cases of afibrinogenemia are due to truncating mutations. Variations in position Arg-35 (the site of cleavage of fibrinopeptide a by thrombin) leads to alpha- dysfibrinogenemias. Defects in FGA are a cause of amyloidosis type 8 (AMYL8); also known as systemic non-neuropathic amyloidosis or Ostertag-type amyloidosis. AMYL8 is a hereditary generalized amyloidosis due to deposition of apolipoprotein A1, fibrinogen and lysozyme amyloids. Viscera are particularly affected. There is no involvement of the nervous system. Clinical features include renal amyloidosis resulting in nephrotic syndrome, arterial hypertension, hepatosplenomegaly, cholestasis, petechial skin rash. 2 isoforms of the human protein are produced by alternative splicing.

Protein type: Secreted, signal peptide; Secreted

Chromosomal Location of Human Ortholog: 4q28

Cellular Component: extracellular space; cell surface; fibrinogen complex; plasma membrane; extracellular region; cell cortex; vesicle; external side of plasma membrane

Molecular Function: protein binding, bridging; protein binding; cell adhesion molecule binding; structural molecule activity; receptor binding

Biological Process: protein polymerization; platelet activation; extracellular matrix organization and biogenesis; positive regulation of heterotypic cell-cell adhesion; cell-matrix adhesion; signal transduction; cellular protein complex assembly; platelet degranulation; positive regulation of protein secretion; positive regulation of vasoconstriction; innate immune response; blood coagulation; response to calcium ion; positive regulation of exocytosis

Disease: Amyloidosis, Familial Visceral; Afibrinogenemia, Congenital; Dysfibrinogenemia, Congenital