Prothrombin structure: unanticipated features and opportunities.

The structure of prothrombin has eluded investigators for decades but recent efforts have succeeded in revealing the architecture of this important clotting factor. Unanticipated features have emerged outlining the significant flexibility of the zymogen due to linker regions connecting the γ carboxyglutamic domain, kringles and protease domain. A new, structure-based framework helps in defining a molecular mechanism of prothrombin activation, rationalizes the severe bleeding phenotypes of several naturally occurring mutations and identifies targets for drug design.