Teo Chin Fen, Tuomivaara Sami T, van Hilten Niek, Crottès David, Jan Yuh Nung, Grabe Michael, Jan Lily Y
bioRxiv. 2025 Jun 27:2025.06.25.661602. doi: 10.1101/2025.06.25.661602.
The asymmetric resting distribution of the three major phospholipid classes on the mammalian plasma membrane, with phosphatidylserine and phosphatidylethanolamine mostly on the inner leaflet, and phosphatidylcholine mostly on the outer leaflet, is maintained by ATP-dependent flippases and floppases that exhibit headgroup selectivity. Upon signaling cues, this asymmetry can be dissipated by various phospholipid scramblases, allowing cells to respond to stimuli and adapt to different physiological contexts. The prevailing view in the field is that phospholipid scramblases on the plasma membrane act without headgroup preference. Here we report contrary experimental evidence based on a phospholipid scrambling assay that quantifies the fluorescence polarization of nitrobenzoxadiazole-labeled phospholipids for kinetic monitoring of phospholipid scrambling on the plasma membrane of living cells. Our experiments reveal that the plasma membrane-residing calcium-activated phospholipid scramblase TMEM16F preferentially acts on phosphatidylserine and phosphatidylcholine over phosphatidylethanolamine.
三种主要磷脂类在哺乳动物质膜上的不对称静息分布得以维持，其中磷脂酰丝氨酸和磷脂酰乙醇胺主要位于内膜层，而磷脂酰胆碱主要位于外膜层，这是由具有头部基团选择性的ATP依赖型翻转酶和翻转酶实现的。在信号提示下，这种不对称性可被各种磷脂翻转酶消除，使细胞能够对刺激做出反应并适应不同的生理环境。该领域的主流观点是质膜上的磷脂翻转酶作用时不具有头部基团偏好性。在此，我们基于一种磷脂翻转测定法报告了相反的实验证据，该测定法通过量化硝基苯并恶二唑标记的磷脂的荧光偏振来动态监测活细胞质膜上的磷脂翻转。我们的实验表明，位于质膜上的钙激活磷脂翻转酶TMEM16F对磷脂酰丝氨酸和磷脂酰胆碱的作用优先于磷脂酰乙醇胺。
