Outline of the pIRES neo 2 A1-A2-A3 WT construct. The protein contains the A1 through A3 domain of von Willebrand factor (VWF) plus a short segment of the D3 domain (residues V1229 through L1871). The VWF fragment is enveloped by a N-terminal Tag100 and HA sequence and a C-terminal (3 ×) FLAG and (6 ×) HIS sequence, respectively. The proteolytic cleavage site (PS) for ADAMTS13 is located in the A2 domain between residues Y1605 and M1606 (marked by an arrow). SP indicates signal peptide; pro, first 3 residues of the VWF propeptide.