Rock P, Allietta M, Young W W, Thompson T E, Tillack T W
Department of Pathology, University of Virginia Health Sciences Center, Charlottesville 22908.
Biochemistry. 1990 Sep 11;29(36):8484-90. doi: 10.1021/bi00488a040.
The techniques of ultrafast freezing and freeze-etch electron microscopy have been successfully employed to visualize IgG molecules and Fab fragments specifically bound to the neutral glycosphingolipids Forssman and asialo-GM1 incorporated into phosphatidylcholine liposomes. Monovalent Fab is the superior marker because of its small size and because it does not cause liposomal aggregation with concomitant glycolipid reorganization. Analysis of Fab labeling of liposomes containing these neutral glycosphingolipids leads to the conclusion that the Forssman glycosphingolipid is dispersed in clusters of not more than several molecules when present at low mole fraction in fluid-phase 1-palmitoyl-2-oleoylphosphatidylcholine liposomes. In contrast to this, asialo-GM1 under the same conditions is present in clusters of about 15 molecules in this phospholipid matrix.
超快冷冻和冷冻蚀刻电子显微镜技术已成功用于可视化特异性结合到掺入磷脂酰胆碱脂质体中的中性糖鞘脂福斯曼抗原（Forssman）和去唾液酸神经节苷脂GM1（asialo-GM1）上的IgG分子和Fab片段。单价Fab是更优的标记物，因为其尺寸小，且不会导致脂质体聚集以及伴随的糖脂重排。对含有这些中性糖鞘脂的脂质体进行Fab标记分析得出结论：当福斯曼糖鞘脂以低摩尔分数存在于液相1-棕榈酰-2-油酰磷脂酰胆碱脂质体中时，它以不超过几个分子的簇状分散。与此相反，在相同条件下，去唾液酸神经节苷脂GM1在这种磷脂基质中以约15个分子的簇状存在。
