Storrie B, Edelson P J
Cell. 1977 Jul;11(3):707-17. doi: 10.1016/0092-8674(77)90087-3.
Indirect immunofluorescence of intact or acetone-extracted cells has allowed us to distinguish concanavalin A (Con A) which is associated with the plasma membrane of CHO cells from Con A which has been interiorized. We find that Con A is directly endocytized by these cells with no intervening stage of plasma membrane aggregation. The lectin accumulations observed by direct fluorescence are actually cytoplasmic collections of pinosomes which contain Con A. Only in a small fraction of CHO cells are true plasma membrane aggregates, or caps, found. This predominance of direct pinocytic interiorization over capping was not affected by dibutyryl cAMP or by treatments which can disrupt microtubules, including cold shock or exposure of the cells to anti-mitotic agents. Cytochalasin B, however, inhibited the uptake of Con A and at the same time promoted the formation of large surface aggregates of the lectin, or minicaps. Capping may reflect a competition between aggregation in the plane of the membrane and direct interiorization of bound lectin. Surface cap formation may be a characteristic process of cells with very low endocytic rates, such as lymphocytes.
对完整细胞或经丙酮抽提的细胞进行间接免疫荧光检测，使我们能够区分与中国仓鼠卵巢（CHO）细胞质膜相关的伴刀豆球蛋白A（Con A）和已内化的Con A。我们发现，Con A可被这些细胞直接内吞，不存在质膜聚集的中间阶段。通过直接荧光观察到的凝集素聚集物实际上是含有Con A的胞饮体的细胞质集合。仅在一小部分CHO细胞中发现了真正的质膜聚集物或帽状结构。这种直接胞饮内化作用相对于帽状形成的优势不受二丁酰环磷腺苷（dibutyryl cAMP）或可破坏微管的处理（包括冷休克或使细胞暴露于抗有丝分裂剂）的影响。然而，细胞松弛素B抑制了Con A的摄取，同时促进了凝集素大表面聚集物或微帽的形成。帽状形成可能反映了膜平面内的聚集与结合凝集素的直接内化之间的竞争。表面帽状结构的形成可能是内吞率极低的细胞（如淋巴细胞）的一个特征性过程。
