Fisher K A
Proc Natl Acad Sci U S A. 1976 Jan;73(1):173-7. doi: 10.1073/pnas.73.1.173.
Membrane splitting by freeze-fracture has been used as a preparative tool for chemical analysis of outer and inner "half"-membranes. In a previous report I showed that monolayers of human erythrocytes, bound to cationized glass, fracture nonrandomly, producing membrane fractions substantially enriched in outer or inner "halves." For the present study cells were used in quantities compatible with microanalysis. For quantitation the total amount of membrane present and the fractional enrichment of outer and inner "half"-membranes were determined. Cholesterol was examined by quantitative thin-layer chromatography modified to assay nanogram amounts. Comparison of lipids extracted from intact membranes with lipids from fractured membranes indicated that cholesterol was asymmetrically distributed across the plane of the membrane, more being present on the exterior side than on the interior side.
冷冻断裂造成的膜分裂已被用作一种制备工具，用于对外部和内部“半”膜进行化学分析。在之前的一份报告中，我表明，结合在阳离子化玻璃上的人红细胞单层会以非随机方式断裂，产生在外部或内部“半”膜中大量富集的膜组分。在本研究中，使用的细胞数量与微量分析相适配。为了进行定量，测定了膜的总量以及外部和内部“半”膜的富集分数。通过改进以测定纳克量的定量薄层色谱法检测胆固醇。将从完整膜中提取的脂质与断裂膜中的脂质进行比较表明，胆固醇在膜平面上呈不对称分布，外侧比内侧含量更多。
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