Comparison of Three Ternary Lipid Bilayer Mixtures: FRET and ESR Reveal Nanodomains
Comparison of Three Ternary Lipid Bilayer Mixtures: FRET and ESR Reveal Nanodomains
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DOI：
10.1016/j.bpj.2010.09.064
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发表时间：
2010-11-17
影响因子：
3.4
通讯作者：
Feigenson, Gerald W.
中科院分区：
文献类型：
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作者：
Heberle, Frederick A.;Wu, Jing;Feigenson, Gerald W.
含有胆固醇的三元脂质混合物的相图为了解细胞膜行为提供了宝贵的见解，特别是通过描述共存的液体无序 (Ld) 和液体有序 (Lo) 相的区域。巨型单层囊泡的荧光显微镜成像极大地帮助了这些系统中相行为的确定。然而，对光学解析 Ld + Lo 结构域的要求可能会导致错误的推论，即在纯脂质混合物中，Ld + Lo 结构域共存通常显示宏观结构域。在这里，我们证明这一推论对于哺乳动物质膜中丰富的低熔点磷脂酰胆碱是不正确的。通过使用高成分分辨率福斯特共振能量转移测量，结合电子自旋共振数据和光谱模拟，我们发现 DSPC 和胆固醇以及 POPC 或 SOPC 的三元混合物确实具有 Ld + Lo 共存区域。然而，相域远小于光学分辨率极限，可能约为能量转移的福斯特距离（R-0，类似于 2-8 nm）。
Phase diagrams of ternary lipid mixtures containing cholesterol have provided valuable insight into cell membrane behaviors, especially by describing regions of coexisting liquid-disordered (Ld) and liquid-ordered (Lo) phases. Fluorescence microscopy imaging of giant unilamellar vesicles has greatly assisted the determination of phase behavior in these systems. However, the requirement for optically resolved Ld + Lo domains can lead to the incorrect inference that in lipid-only mixtures, Ld + Lo domain coexistence generally shows macroscopic domains. Here we show this inference is incorrect for the low melting temperature phosphatidylcholines abundant in mammalian plasma membranes. By use of high compositional resolution Forster resonance energy transfer measurements, together with electron spin resonance data and spectral simulation, we find that ternary mixtures of DSPC and cholesterol together with either POPC or SOPC, do indeed have regions of Ld + Lo coexistence. However, phase domains are much smaller than the optical resolution limit, likely on the order of the Forster distance for energy transfer (R-0, similar to 2-8 nm).