Molecular characterization of a human monoclonal antibody that interacts with a sulfated tyrosine-containing epitope of the GPIb receptor and inhibits platelet functions.

Modification of tyrosine residues in extracellular proteins by a sulfate moity plays an important role in many ligand/receptors interactions. In the present work, we describe a unique human monoclonal antibody, termed Y1-scFv, that is specific for a sulfated epitope in the platelat receptor GPIb. The Y1-scFv single chain antibody (scFv) competes with von Willebrand factor (vWF) for binding to human platelets and thus effectively inhibits platelet aggregation.