ADAMTS13 (A disintegrin and metalloprotease with TSP motifs 13) is a 140-230kD, secreted glycoprotein member of the ADAMTS family of proteases. ADAMTS13 is produced by the liver and circulates in plasma where it cleaves and reduces the activity of von Willebrand factor. ProADAMTS13 is 1398aa in length. It contains a 45aa prodomain (aa30-74), one peptidase domain (aa80-286) and one disintegrin (aa287-383) domain, multiple TSP regions and two CUB domains. The prodomain does not affect activity, while the TSP and CUB domains appear to be necessary for activity. One truncated form exists that shows truncation after Gln448. Over aa34-688, human ADAMST13 shares 76% aa identity with mouse ADAMST13.