Thrombin interaction with platelet GpIb: structural mapping and effects on platelet activation (review)

Platelet glycoprotein Ib (GpIb) is an integral platelet membrane glycoprotein which plays a major role in haemostasis, being involved in both von Willebrand factor (vWF) and alpha-thrombin high affinity binding. Such interactions contribute to the early adhesion of platelets to exposed subendothelium and to the process of platelet activation. Glycoprotein Ib belongs to the so called (LRR) family of proteins, characterized by a structural motif consisting of the presence of one or more tandem LRRs, flanked by conserved sequences. Several experimental strategies have recently documented the involvement of the thrombin domain referred to as 'heparin binding site' in the binding to GpIb. This review is aimed at reporting on the structural mapping of both alpha-thrombin and GpIb domains involved in such interaction and on possible roles of thrombin-GpIb binding on the mechanisms supporting the platelet activation.