Fig. 1. Schematic representation of prothrombin kringle-2 (pKr-2) generation from prothrombin. Prothrombin consists of Gla, Kringle-1, Kringle-2, and the serine protease domain (thrombin). Prothrombin is cleaved by Factor Xa into two fragments: fragment 1 plus 2, which includes Gla, Kringle-1, and Kringle-2; and a protease catalytic domain, thrombin. Active thrombin then cleaves fragment 1 plus 2 into fragment 1, which includes Gla and Kringle-1, and fragment 2, which consists of Kringle-2, which then produces pKr-2. The red arrows indicate the proteolytic activity of Factor Xa and thrombin, and the blue arrows indicate the domains of proteolytic activity.
