Thrombin interaction with platelet GpIb: Structural mapping and effects onplatelet activation (Review)

Platelet glycoprotein Ib (GpIb) is an integral platelet membrane glycoprote in which plays a major role in haemostasis, being involved in both von Will ebrand factor (VWF) and alpha-thrombin high affinity binding. Such interact ions contribute to the early adhesion of platelets to exposed subendotheliu m and to the process of platelet activation. Glycoprotein Ib belongs to the so called 'leucine rich repeat' (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 recent ly documented the involvement of the thrombin domain referred to as 'hepari n binding site' in the binding to GpIb. This review is aimed at reporting o n the structural mapping of both alpha-thrombin and GpIb domains involved i n such interaction and on possible roles of thrombin-GpIb binding on the me chanisms supporting the platelet activation.