Phospholipids are asymmetrically distributed at plasma membrane in normal cells, but their distribution is collapsed by phospholipid scrambling in various biological situations such as blood clotting and apoptotic cell death. Although the molecular mechanism of phospholipid scrambling was unknown until recently, Dr. Shigekazu Nagata and I found that phospholipid scrambling is mediated by at least two independent mechanisms. An eight transmembrane-containing protein TMEM16F Ca(2+)-dependently promotes the phospholipid scrambling in activated platelets for blood clotting. On the other hand, a six transmembrane-containing protein Xkr8 is activated by caspases during apoptosis and promotes the phospholipid scrambling, thus exposing phosphatidylserine as an “eat-me-signal”.

Jun Suzuki, PhD

Assistant Professor,
Graduate School of Medicine