Mutations in the gene encoding the alpha chain of platelet glycoprotein IB

The subject invention provides purified polypeptides encoded by naturally-occurring wild-type platelet glycoprotein Ib alpha having a mutation which renders the polypeptide more reactive with von Willebrand factor. Preferably, the mutation is in the hinge region of GP Ib alpha, such as the substitution of valine for glycine at residue 233. These mutations alter the three-dimensional structure of the mutant polypeptide from a beta bend conformation to an alpha helix formation, and also create an amphipathic region within the mutant polypeptide. DNA encoding the mutant polypeptides, as well as expression systems for the production of the mutant polypeptides, are also provided. Methods and compositions using the mutant polypeptides and DNA oligomers complementary to the mutant polypeptides are further provided.