Margolis L B, Neyfakh A A
Eur J Cell Biol. 1983 Sep;31(2):256-62.
Interaction of large multilamellar and small sonicated liposomes with epithelial sheets in culture has been studied. Liposomes were comprised of dipalmitoyl- or distearoylphosphatidylcholine and were solid at 37 degrees. Sodium fluorescein was entrapped in liposomes and their localization on the cell surface was studied by fluorescence microscopy. The distribution of liposomes depends on their size. Large liposomes adhere uniformly all over the surface of the sheet, which proved to be nonadhesive either for other cells or for inert particles. Small liposomes adhere mostly along the margins of the sheet. When the cells are partly detached from each other by mild EDTA (ethylene diamine tetraacetic acid) treatment, the newly accessible cell margins become capable of binding small liposomes. The binding of both types of liposomes is trypsin-sensitive; however large liposomes, bound along the edges of the cellular sheet, are removed slower than those adhering to the inner parts of the sheet. Competition experiments show that large and small liposomes bind to the same sites on the surface of the sheet. Liposome-acceptor proteins are suggested to exist on the surface of epithelial cells. We suppose that these proteins are concentrated along the cell margins and are involved in cell-cell contacts.
已对培养物中大型多层脂质体和小型超声处理脂质体与上皮细胞片层的相互作用进行了研究。脂质体由二棕榈酰磷脂酰胆碱或二硬脂酰磷脂酰胆碱组成，在37℃时呈固态。将荧光素钠包封在脂质体中，并通过荧光显微镜研究其在细胞表面的定位。脂质体的分布取决于其大小。大型脂质体均匀地附着在片层的整个表面，该片层被证明对其他细胞或惰性颗粒均无粘附性。小型脂质体大多沿着片层的边缘附着。当通过温和的乙二胺四乙酸（EDTA）处理使细胞彼此部分分离时，新暴露的细胞边缘能够结合小型脂质体。两种类型脂质体的结合均对胰蛋白酶敏感；然而，沿着细胞片层边缘结合的大型脂质体比附着在片层内部的脂质体去除得慢。竞争实验表明，大型和小型脂质体结合到片层表面的相同位点。提示上皮细胞表面存在脂质体受体蛋白。我们推测这些蛋白集中在细胞边缘并参与细胞间接触。
