Fibrinopeptide A [Tyr0] Peptide – Synthetic Peptide, ~95%. Purified by HPLC. Purity

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]

Function: Fibrinogen has a double function: yielding monomers that polymerize into fibrin and acting as a cofactor in platelet aggregation.

Subunit structure: Heterohexamer; disulfide linked. Contains 2 sets of 3 non-identical chains (alpha, beta and gamma). The 2 heterotrimers are in head to head conformation with the N-termini in a small central domain. Ref.18

Subcellular location: Secreted.

Tissue specificity: Plasma.

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.

Post-translational modification: The alpha chain is not glycosylated. Ref.26Forms F13A-mediated cross-links between a glutamine and the epsilon-amino group of a lysine residue, forming fibronectin-fibrinogen heteropolymers.About one-third of the alpha chains in the molecules in blood were found to be phosphorylated. Ref.20Conversion 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.Phosphorylation sites are present in the extracellular medium.

Involvement in disease: Congenital afibrinogenemia (CAFBN) [MIM:202400]: Rare autosomal recessive disorder is characterized by bleeding that varies from mild to severe and by complete absence or extremely low levels of plasma and platelet fibrinogen.Note: The disease is caused by mutations affecting the gene represented in this entry. 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.Amyloidosis 8 (AMYL8) [MIM:105200]: 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.Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.36

Sequence similarities: Contains 1 fibrinogen C-terminal domain.