Identification of the PAR1 and PAR3 cleavage sites for FXa. Proteolysis of a synthetic PAR1 (P1: residues 33-62) and PAR3 (P3: residues 21-65) peptide by FXa, APC, and thrombin. (A) Chromatogram of P1 fragments generated in the absence (none) or presence of FXa (150 nM; 1 hour), thrombin (IIa) (10 nM; 1 hour), or APC (500 nM; 15 hours). (B) Concentration-dependent cleavage of the P1 peptide by FXa (1 hour). (C) Time-dependent cleavage of the P1 peptide by FXa (25 nM). (D) Chromatogram of the P3 fragments generated by FXa (150 nM; 1 hour) and thrombin (10 nM; 1 hour). Peptide P3 and the C-terminal fragments after cleavage at Lys38 (P3K) or Arg41 (P3R) are indicated for reference. (E) Concentration-dependent cleavage of the P3 peptide by FXa (10 hours). (F) Time-dependent cleavage of the P3 peptide by FXa (150 nM). (A, D) Representative chromatograms. (B-C,E-F) Data points represent the mean ± standard deviation (SD) of 3 independent experiments.