Flip-Flop of Phospholipids in Vesicles: Kinetic Analysis with Time-Resolved Small-Angle Neutron Scattering
Flip-Flop of Phospholipids in Vesicles: Kinetic Analysis with Time-Resolved Small-Angle Neutron Scattering
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DOI：
10.1021/jp900913w
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发表时间：
2009-05-14
影响因子：
3.3
通讯作者：
Handat, Tetsurou
中科院分区：
文献类型：
--
作者：
Nakano, Minoru;Fukuda, Masakazu;Handat, Tetsurou
我们应用了时间分辨小角度。囊泡系统的中子散射技术以确定磷脂的颗粒间转移和翻转。对大的单层囊泡进行了测量，这些囊泡由二肉豆蔻酰磷脂酰胆碱 (DMPC)、1-棕榈酰-2-油酰磷脂酰胆碱 (POPC) 或 1-棕榈酰-2-油酰磷脂酸 (POPA) 组成，它们的酰基链或头基不同。 POPC 与天然存在的磷脂酰胆碱类似，没有表现出跨双层转移和非常缓慢的双层间迁移。即使当磷脂酶 D 将外叶上的所有 POPC 分子转化为 POPA 时，囊泡内叶上的 POPC 也不会翻转，这显示出快速翻转。从这些结果，加上在胆固醇存在下DMPC的翻转被完全抑制的观察结果，推断出磷脂酰胆碱的翻转在富含胆固醇的细胞质膜中不会自发发生，并且它需要能量依赖性的酶活性。和/或-独立的翻转/翻转。
We applied a time-resolved small-angle. neutron scattering technique to vesicle systems to determine interparticle transfer and flip-flop of phospholipids. Measurements were performed for large unilamellar vesicles, consisting of dimyristoylphosphatidylcholine (DMPC), 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), or 1-palmitoyl-2-oleoylphosphatidic acid (POPA), which differ either in their acyl chains or headgroup. POPC, which is analogous to naturally occurring phosphatidylcholines, exhibited no transbilayer transfer and very slow interbilayer migration. POPC on the inner leaflet of vesicles did not flop even when phospholipase D converted all POPC molecules on the outer leaflet into POPA, which was shown to exhibit fast flip-flop. From these results, together with the observation that the flip-flop of DMPC was entirely inhibited in the presence of cholesterol, it is deduced that the flip-flop of phosphatidy1cholines does not take place spontaneously in cellular plasma membranes rich in cholesterol and that it requires enzymatic activities of energy-dependent. and/or -independent flippases/floppases.