Bretscher M S
Proc Natl Acad Sci U S A. 1983 Jan;80(2):454-8. doi: 10.1073/pnas.80.2.454.
Giant HeLa cells, having a spread diameter of about 200 micrometers, were briefly surface-labeled at 0 degree C with 125I-labeled transferrin, low density lipoprotein, anti-HeLa cell antibody, or concanavalin A. The cells were washed at 0 degree C, fixed, and autoradiographed. The distribution of grains when either anti-HeLa cell antibodies or concanavalin A was used was roughly as expected: the cell surfaces appeared uniformly labeled. When either transferrin or low density lipoprotein was used, about half the labeled cells had a nonuniform distribution of grains. On round cells, the cell periphery was more densely labeled than the middle of the cell; on elongated cells, cell protrusions were often more highly labeled than the rest of the cell. The simplest interpretation of these results is that, during their endocytic cycles through these cells, the transferrin and low density lipoprotein receptors are returned to the cell surface at the cell's leading edge.
直径约200微米的巨大海拉细胞在0℃下用125I标记的转铁蛋白、低密度脂蛋白、抗海拉细胞抗体或伴刀豆球蛋白A进行短暂的表面标记。细胞在0℃下洗涤、固定并进行放射自显影。当使用抗海拉细胞抗体或伴刀豆球蛋白A时，颗粒的分布大致符合预期：细胞表面呈现均匀标记。当使用转铁蛋白或低密度脂蛋白时，约一半的标记细胞具有不均匀的颗粒分布。在圆形细胞上，细胞周边的标记比细胞中部更密集；在细长细胞上，细胞突起的标记通常比细胞其他部分更高。对这些结果最简单的解释是，在通过这些细胞的内吞循环过程中，转铁蛋白和低密度脂蛋白受体在细胞的前沿被返还到细胞表面。
