Phosphatidylserine exposed on the outer leaflet of apoptotic cell membrane (PS (often used for phosphatidylserine))

Phosphatidylserine (PS) is a phospholipid component normally confined to the inner leaflet of the plasma membrane in healthy cells due to the action of ATP-dependent flippases[1][3][4]. During apoptosis, caspase-mediated inactivation of flippases and activation of scramblases (such as Xkr8 and TMEM16F) cause PS to translocate to the outer leaflet[2][3][4]. This externalized PS acts as an “eat me” signal recognized by phagocytic cells—including macrophages and dendritic cells—facilitating non-inflammatory clearance of apoptotic cells[2][3][4][5]. Exposed PS is a target for therapies aiming to modulate cell clearance (for example, in cancer), a marker for apoptosis in diagnostics, and also serves as a platform for coagulation on activated platelets[1][4][5]. PS exposure is implicated in diverse diseases, including cancer, infection, and chronic inflammation, where deregulated cell death or defective clearance may occur.

Other names

Phosphatidylserine (apoptotic cell surface)Externalized phosphatidylserinePS exposureApoptotic cell “eat me” signal

Antibody-dependent cellular cytotoxicity (when targeted by antibodies such as bavituximab) Phagocytosis enhancement (as a recognition signal for clearance by immune cells)