Cross species alignment of FV sequences in the vicinity of (A) human APC cleavage sites R306 and R506; (B) thrombin cleavage sites; and (C) the acidic region at the C-terminus of the heavy chain, including the human APC cleavage site R679. Cleavage sites are numbered according to either the human (hFV) or bovine (bFV) protein, as indicated in parentheses. The “↓” indicates the cleavage site in both (A) and (B) at the conserved underlined arginine residue. The third APC cleavage site (C) varies between the human and bovine proteins, as indicated. Only the sequence surrounding the FV APC cleavage site R506 is conserved between FV and FVIII; all other APC and thrombin cleavage sites fail to show significant homology across these two proteins (not shown).