Schematic of potential interactions between GP V and GP Ibα in forming a high-affinity site for thrombin. GP V is depicted between 2 GP Ib-IX complexes, associating with these complexes directly through GP Ibα. In the process of this association, GP Ibα regions important for thrombin binding on 2 nearby polypeptides may become juxtaposed or be influenced allosterically by GP V. Structures of the leucine-rich repeats of the polypeptides are drawn based on the crystal structure of the porcine ribonuclease inhibitor determined by Kobe and Diesenhofer.51