A small portion of the D3 domain of VWF is crucial for association with VWFpp.

(A) Schematic representation of chimeric human/canine Δpro and summary of storage and multimerization data. The domain structure of Δpro is depicted at the top and chimeric Δpro's are depicted below. Portions of Δpro containing human sequence are depicted in black and those containing canine sequence in white. The summarized data are for coexpression of the chimeric Δpro intrans with canine VWFpp. The area of overlapping canine sequence for those chimeric VWFpp's that sorted to storage with canine VWFpp is shown between the 2 vertical lines; it lies between amino acids 866 and 907 in the D3 domain. (B) Sequence comparison of human and canine Δpro beginning at the D3 domain, amino acid 866. There is only 1 amino acid difference between the human and canine VWFpp sequence in this region.