What Causes Asymmetry in the Phospholipid Bilayer?

💡 The Answer

• Flippases, floppases, and scramblases actively transport specific lipids between leaflets.
• Outer leaflet is rich in phosphatidylcholine and sphingomyelin, inner leaflet in phosphatidylserine and PE.
• This asymmetry is crucial for cell signaling—exposure of PS on outer surface triggers apoptosis.
• Loss of asymmetry is linked to cancer and blood clotting disorders.