Figure 2.

Schematic representation of the two possible pathways of thrombin generation from its precursor prothrombin. The three-dimensional structures of prothrombin (PDB entry 6c2w), thrombin (PDB entry 1ppb), meizothrombin (PDB entry 3e6p), and prethrombin-2 (PDB entry 4rn6) are shown. In the meizothrombin, the fragment 1 (GLA domain and kringle-1), which is absent in the crystal structure, is schematically represented. After the proteolysis of the Arg320-Ile321 peptide bond, the protease domain (dark blue) is divided into the heavy (dark green) and light (light green) chains, which are connected through a disulfide bond.