Imaging supported lipid bilayers and actual cell membrane fragments by NanoSIMS

描述（由申请人提供）：支持的脂质双分子层已被用作研究具有定义成分的模型膜的生物物理特性的工具。特别关注胆固醇在脂质膜相行为中的作用，特别是脂质“筏”或结构域和复合物的形成。用于阐明二元和三元脂质双层相行为的常用技术（即荧光和原子力显微镜）由于无法提供膜空间组成的直接信息而受到限制。二次离子质谱（NanoSIMS）是成像脂质双分子层横向组织和组成的有力工具。由于脂质双分子层中的成分是通过同位素标记唯一识别的，因此NanoSIMS可以明确地识别小至50nm的区域内共定位的不同分子。在这些研究中，描述了一种生产高水平13C富集的胆固醇同位素体的方法。此外，NanoSIMS将用于成像天然细胞膜片段中胆固醇和蛋白质的空间分布和共定位。

DESCRIPTION (provided by applicant): Supported lipid bilayers have been used as a tool to study the biophysical properties of model membranes with defined compositions. Special attention has been given to the role of cholesterol on the phase behavior of lipid membranes, in particular, to the formation of lipid "rafts" or domains and complexes. Common techniques used to elucidate the phase behavior of binary and ternary lipid bilayers (i.e. fluorescence and atomic force microscopy) have been limited by their inability to provide direct information on the spatial composition of membranes. Secondary ion mass spectrometry (NanoSIMS) is a powerful tool for imaging the lateral organization and composition of lipid bilayers. Because the components in a lipid bilayer are uniquely identified by isotopic labels, NanoSIMS can unambiguously identify different molecules co-localized in a region as small as 50nm. In these studies, a method for producing cholesterol isotopomers at high levels of 13C enrichment is described. Furthermore, NanoSIMS will be used to image the spatial distribution and co-localization of cholesterol and proteins in native cell membrane fragments. PUBLIC HEALTH RELEVANCE: The lipid bilayer of a cell membrane is a complex and dynamic system in terms of lateral composition and organization. Living cells depend on the concerted rearrangement of membrane components, such as cholesterol, lipids, and proteins; yet very little is known about how this organization changes during essential processes, such as, cell-cell interactions, signal transduction, membrane trafficking, and membrane-bound protein activity and accessibility. In these studies, secondary ion mass spectrometry (nanoSIMS) imaging will be used to obtain quantitative compositional information with nanometer scale resolution of model and actual cell membranes.