The role of heterotrimeric G proteins in platelet activation

Activation of platelets plays a central role in hemostasis as well as in va rious thromboembolic diseases like myocardial infarction or stroke. Most pl atelet activating stimuli function through receptors which couple to hetero trimeric G proteins of the G(i), G(q) and G(12) families. Recent studies ha ve elucidated the roles of individual G proteins in the regulation of plate let functions like shape change, aggregation and granule secretion. The sig naling pathways mediated by heterotrimeric G proteins operate synergistical ly to induce a full activation of platelets. This review summarizes recent progress in the understanding of upstream regulation of platelet activation through G protein-coupled receptors.