Localization of phosphatidylethanolamine in the plasma membrane of diamide-treated human blood platelets.

In human blood platelet plasma membranes phosphatidylethanolamine (PE) is asymmetrically distributed between the two leaflets. The main part of this phospholipid is localized at the inner half of the lipid bilayer. Upon stimulation of the cell a substantial transbilayer movement of PE as well as phosphatidylserine occurs and the outer leaflet then provides a procoagulant surface. The thrombin-induced PE flip-flop is inhibited by pretreatment of platelets with diamide, whereas pretreatment of platelets with diamide alone up to 5 mM did not change considerably the localization of PE in the platelet membrane. Thus, cytoskeletal proteins, which are modified by diamide, are not involved in the maintenance of the PE asymmetry but are important for the realization of the agonist-induced events in the platelets.