Fig. 3.
The structure of prekallikrein. The letters A1 through A4 represent the apple domains of prekallikrein's heavy chain. The notation Factor XIIa and arrow at arginine371 represent the factor XIIa activation site on prekallikrein. Histidine415 , aspartic acid464 , and serine559 represent kallikrein's catalytic active site. A circle with a shaded background represents the regions involved in binding to high molecular weight kininogen. Adapted from Chung et al.89
