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. Author manuscript; available in PMC: 2015 Sep 1.
Published in final edited form as: Drug Discov Today. 2014 Jun 2;19(9):1454–1458. doi: 10.1016/j.drudis.2014.05.018

Figure 2.

Figure 2

Schematic diagram of factor (f)XI. Shown are the primary amino acid sequence, disulfide bonds (cysteine residues shown in black circles) and domain structure of human plasma fXI. The histidine (413), aspartic acid (462) and serine (557) residues of the protease active site catalytic triad are shown in red. Conversion of fXI to fXIa involves a single proteolytic cleavage after Arg369 (indicated in blue) that can be produced by fXIIa or thrombin. Residues that are required for fIX binding to the A3 domain are indicated in yellow, and residues that comprise a polyanion (heparin) binding site on the catalytic domain are in green. Mature fXI is a dimer of the protein shown in this figure. The unpaired cysteine residue at position 321 (Cys321) in a fXI subunit forms an inter-chain disulfide bond with Cys321 from the other subunit of the dimer. Image reproduced, with permission, from [41].