Anionic phospholipid membrane surface (PS-rich membrane)

Anionic phospholipid membrane surfaces, primarily characterized by the exposure of phosphatidylserine (PS), serve as essential catalytic scaffolds for the assembly of blood coagulation factor complexes. In healthy, resting cells, these phospholipids are actively sequestered in the inner leaflet of the plasma membrane by flippase enzymes. However, upon platelet activation or during cellular stress and apoptosis in tissue factor (TF)-expressing cells, PS is externalized to the outer leaflet via scramblase activity. This exposed anionic surface provides a high-affinity binding site for the gamma-carboxyglutamic acid (Gla) domains of vitamin K-dependent clotting factors, including Factors II, VII, IX, and X. The assembly of the tenase and prothrombinase complexes on this surface accelerates thrombin generation by several orders of magnitude compared to solution-phase reactions. In the context of disease, aberrant PS exposure is a hallmark of the tumor microenvironment, where it contributes to immunosuppression, and in cardiovascular disease, where it drives pathological thrombosis. Therapeutic agents such as bavituximab and Annexin A5 derivatives target these surfaces to either block the coagulation cascade or re-engage the immune system against tumor cells.

Other names

Phosphatidylserine-exposed membraneProcoagulant membraneActivated platelet surfacePhosphatidylserine (PS)Anionic phospholipid surface

Competitive binding to exposed phosphatidylserine to inhibit the assembly of coagulation factor complexes (tenase and prothrombinase) or to modulate immune signaling in the tumor microenvironment.