Two-color near-field fluorescence microscopy studies of microdomains ("Rafts") in model membranes
Two-color near-field fluorescence microscopy studies of microdomains ("Rafts") in model membranes
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DOI：
10.1021/la034551p
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发表时间：
2003-09-16
期刊：
影响因子：
3.9
通讯作者：
Johnston, LJ
中科院分区：
文献类型：
--
作者：
Burgos, P;Yuan, CB;Johnston, LJ
用近场扫描光学显微镜（NSOM）研究了糖脂GM 1在三元脂质混合物支持的磷脂单分子膜中的分布。等摩尔量的鞘磷脂、二油酰磷脂酰胆碱和胆固醇的单层显示出清晰的相分离，以得到被流体相包围的大的凝聚域，如通过原子力显微镜（AFM）和添加优先定位在流体相中的德克萨斯红标记的脂质所可视化的。AFM和一个和两个颜色的NSOM实验的组合表明，添加GM 1-Bodipy的结果在小的糖脂域内的流体相。这与先前的结果相反，表明GM 1定位于相似脂质混合物的凝聚相中，并且归因于染料诱导的糖脂分布变化。然而，NSOM实验的GM 1-Bodipy掺杂低负荷的含GM 1的单层导致在凝聚相内观察到小的荧光微区。NSOM的高空间分辨率允许检测之前未通过荧光观察到的小结构域，并表明通过原子力显微镜和荧光检测到类似但不相同的糖脂分布。这些结果的相关性筏在天然膜进行了讨论。
The distribution of glycolipid GM1 in supported phospholipid monolayers of a ternary lipid mixture has been studied by near-field scanning optical microscopy (NSOM). Monolayers of equimolar amounts of sphingomyelin, dioleoylphosphatidylcholine, and cholesterol show clear phase separation to give large condensed domains surrounded by a fluid phase, as visualized by both atomic force microscopy (AFM) and addition of a Texas Red labeled lipid that localizes preferentially in the fluid phase. A combination of AFM and one- and two-color NSOM experiments indicates that addition of GM1-Bodipy results in small glycolipid domains within the fluid phase. This is in contrast to previous results demonstrating that GM1 is localized in the condensed phase for similar lipid mixtures and is attributed to dye-induced changes in the distribution of the glycolipid. However, NSOM experiments for GM1-containing monolayers doped with low loadings of GM1-Bodipy resulted in the observation of small fluorescent microdomains within the condensed phase. The high spatial resolution of NSOM allows the detection of small domains that have not been observed previously by fluorescence and demonstrates that similar, although not identical, distributions of glycolipid are detected by AFM and fluorescence. The relevance of these results to rafts in natural membranes is discussed.