The structure and evolution of vertebrate fibrinogen: a comparison of the lamprey and mammalian proteins.

The blood plasmas of all vertebrate animals contain a six-chained fibrinogen molecule that is polymerized into fibrin upon the thrombin-catalyzed removal of fibrinopeptides. In all cases, also, the polymerization reaction is inhibited by Gly-Pro-Arg-ending peptides. The complete amino acid sequences of human, rat and lamprey fibrinogens are known, permitting an assessment of just which sequence features are essential for polymerization. To an extent, the same approach can also be applied to the associated phenomena of fibrin cross-linking by factor XIII, plasminogen and plasminogen activator binding, and vessel wall-fibrinogen interactions.