The protein fold of the von Willebrand factor type A domain is predicted to be similar to the open twisted beta-sheet flanked by alpha-helices found in human ras-p21.

The von Willebrand Factor type A domain is the prototype for a protein superfamily. It possesses no significant sequence similarity to any known protein structure. Secondary structure predictions indicate a largely alternating pattern of six alpha-helices and six beta-strands. A protein fold for this domain is proposed to correspond to a doubly-wound open twisted beta-sheet structure flanked by alpha-helices. Close agreement was found with the GTP-binding domain of human ras-p21, provided that an extra alpha-helix was inserted. The structure of the predicted fold showed high compatibility with the proximate location of two Mg(2+)-binding Asp residues, two disulphide-bridged Cys residues, and other known functional attributes of this domain.