Anionic phospholipid membranes on activated platelets (PS-rich membranes)

Anionic phospholipid membranes on activated platelets, primarily characterized by the externalization of phosphatidylserine (PS), serve as a critical catalytic surface for the blood coagulation cascade (Lentz, 2003, PMID: 12835057). In resting platelets, PS is actively maintained in the inner leaflet of the plasma membrane; however, upon activation by stimuli such as thrombin or collagen, the enzyme scramblase facilitates its translocation to the outer leaflet (Heemskerk et al., 2013, PMID: 23614835). This negatively charged surface acts as a scaffold for the assembly of the tenase and prothrombinase complexes, which are essential for the rapid generation of thrombin and subsequent fibrin clot formation (Zwaal et al., 2005, PMID: 15664240). Because this exposure is specific to activated platelets and apoptotic cells, it represents a highly localized therapeutic target for antithrombotic agents and molecular imaging (Schutters & Reutelingsperger, 2010, PMID: 20833516). Drugs targeting these membranes, such as Annexin A5 derivatives, work by masking the anionic sites to prevent the binding of vitamin K-dependent clotting factors, thereby reducing the risk of thrombosis without the systemic side effects of traditional anticoagulants. This target is also central to the pathogenesis of Antiphospholipid Syndrome, where autoantibodies recognize proteins bound to these anionic surfaces (Miyakis et al., 2006, PMID: 16448354).

Other names

Phosphatidylserine-exposed membranesProcoagulant platelet surfaceActivated platelet surfacePS-exposed membranesProthrombotic phospholipid surface

Inhibition of the assembly of tenase and prothrombinase complexes by masking the anionic surface (primarily phosphatidylserine) required for calcium-dependent binding of vitamin K-dependent coagulation factors.