Heterogeneous molecular distribution in supported multicomponent lipid bilayers
Heterogeneous molecular distribution in supported multicomponent lipid bilayers
复制标题
DOI：
10.1021/la0355388
复制
发表时间：
2004-02-03
期刊：
影响因子：
3.9
通讯作者：
Dvorak, JA
中科院分区：
文献类型：
--
作者：
Tokumasu, F;Hwang, J;Dvorak, JA
膜结构域为生物膜提供重要的结构和功能属性。我们描述了由二棕榈酰磷脂酰胆碱（DPPC），二月桂酰磷脂酰胆碱（DLPC）和胆固醇（胆固醇）组成的多组分脂质双层中微尺度膜域内脂质分子的非均匀纳米级分布。用荧光脂质类似物Bodipy-PC和DiI-C20：0标记脂质，以鉴定单个膜组分的分布。我们在室温下使用近场扫描光学显微镜（NSOM）来识别膜中的纳米级结构。在荧光类似物的发射最大值处同时进行多色NSOM成像，发现Bodipy-PC和DiI-C20：0呈片状分布，表明双层中存在相分离。在无胆固醇的体系中（DPPC/DLPC = 1：1），NSOM图像证明两种磷脂酰胆碱分子可以在微米级的区域内共存，但在区域内形成纳米级的斑块; DPPC发生在区域的边缘，而DLPC则存在于整个区域。在胆固醇存在下（DPPC/DLPC = 7：3，chol = 18.9%），两种脂质分子更易混溶，但也发生不完全的相分离。平均域大小为140-200 nm，远低于衍射限制光学显微镜技术的分辨率能力;域是无法解析的共聚焦显微镜。我们的高分辨率NSOM研究膜域的行为提供了一个更好的理解复杂的膜相现象在多组分生物膜。
Membrane domains contribute important structural and functional attributes to biological membranes. We describe the heterogeneous nanoscale distribution of lipid molecules within microscale membrane domains in multicomponent lipid bilayers composed of dipalmitoylphosphatidylcholine (DPPC), dilauroylphosphatidyleholine (DLPC), and cholesterol (chol). The lipids were labeled with the fluorescent lipid analogues Bodipy-PC and DiI-C20:0 to identify the distribution of individual membrane components. We used a near-field scanning optical microscope (NSOM) at room temperature to identify the nanoscale structures in the membrane. Simultaneous multicolor NSOM imaging at the emission maxima of the fluorescent analogues revealed a patchy distribution of Bodipy-PC and DiI-C20:0 indicative of phase separations in the bilayer. In a cholesterol-free system (DPPC/DLPC = 1:1), NSOM images proved that the two phosphatidylcholine molecules can coexist in domains at the micrometer level but form nanoscopic patches within the domains; DPPC occurs at the edge of the domains, whereas DLPC is present throughout the domains. In the presence of cholesterol (DPPC/DLPC = 7:3, chol = 18.9%), the two lipid molecules were more miscible but incomplete phase separations also occurred. The average domain sizes were 140-200 nm, well below the resolution capabilities of diffraction-limited light microscopy techniques; the domains were unresolvable by confocal microscopy. Our high-resolution NSOM studies of membrane domain behavior provide a better understanding of complex membrane phase phenomena in multicomponent biological membranes.