Wu G, Hubbell W L
Jules Stein Eye Institute, University of California, Los Angeles 90024-7008.
Biochemistry. 1993 Jan 26;32(3):879-88. doi: 10.1021/bi00054a020.
The phospholipid asymmetry and flip-flop rate in rod outer segment (ROS) disc membranes has been investigated by both a spin-label reduction method and a novel electron-electron double resonance (ELDOR) method. At 39 degrees C in the absence of ATP, spin-labeled derivatives of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS) undergo rapid transmembrane diffusion, with a half-time of less than 10 min. At equilibrium, approximately 53% of the spin-labeled PC, 37% of the spin-labeled PE, and 18% of the spin-labeled PS reside in the inner (intradiscal) monolayer. The rapid transmembrane diffusion of phospholipids is partially inhibited by N-ethylmaleimide, suggesting that the process is mediated by proteins in the disc membrane.
通过自旋标记还原法和一种新型电子-电子双共振（ELDOR）方法，对视杆细胞外段（ROS）盘膜中的磷脂不对称性和翻转速率进行了研究。在39摄氏度且无ATP的情况下，磷脂酰胆碱（PC）、磷脂酰乙醇胺（PE）和磷脂酰丝氨酸（PS）的自旋标记衍生物会发生快速跨膜扩散，半衰期不到10分钟。在平衡状态下，约53%的自旋标记PC、37%的自旋标记PE和18%的自旋标记PS位于内侧（盘内）单层。磷脂的快速跨膜扩散受到N-乙基马来酰亚胺的部分抑制，这表明该过程是由盘膜中的蛋白质介导的。
