Figure 2.
Schematic of (A) reaction zone and (B) endothelial zone. (C) Schematic of reactions involving fXI or fXIa. (Left) Dimers fXI-fXI and fXI-fXIa can bind (unbind) to (from) the fXI-specific binding sites, whereas fXI-fXIa and fXIa-fXIa can bind (unbind) to (from) the fXIa-specific binding sites. Thrombin can activate fXI to fXIa in solution and on an activated platelet. Only the dangling-end of a bound dimer can be activated by thrombin or can activate fIX. (Right) fXI-fXIa and fXIa-fXIa dimers can activate fIX to fIXa in solution or on an activated platelet.