Outline structure of the FLAG-tagged GPI-anchored vWF–A₁-domain fusion protein expressed on COS-7 cells. The secretion sequence of preprotrypsin, including the FLAG-epitope, was cloned as an oligonucleotide into the pcDNA3 vector. The human and porcine vWF sequence (aa 473-713) cloned from porcine and human endothelial cell RNA by RT-PCR and a further truncated fragment (aa 475*-709*) generated by PCR from human A₁ (aa 473-713) were separately ligated into the vector. Finally, the C-terminal DAF-derived GPI-linker sequence was inserted into the construct.