Futter C E, Gibson A, Allchin E H, Maxwell S, Ruddock L J, Odorizzi G, Domingo D, Trowbridge I S, Hopkins C R
Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England.
J Cell Biol. 1998 May 4;141(3):611-23. doi: 10.1083/jcb.141.3.611.
Human transferrin receptors (TR) and receptors for polymeric immunoglobulins (pIgR) expressed in polarized MDCK cells maintain steady-state, asymmetric distributions on the separate basolateral and apical surfaces even though they are trafficking continuously into and across these cells. The intracellular mechanisms required to maintain these asymmetric distributions have not been located. Here we show that TR and pIgR internalize from both surfaces to a common interconnected endosome compartment that includes tubules with buds coated with clathrin lattices. These buds generate vesicles that carry TR to the basolateral border. The lattices contain gamma-adaptin and are dispersed by treatment with brefeldin A (BFA). Since BFA treatment abrogates the vectorial trafficking of TR in polarized MDCK cells, we propose that the clathrin-coated domains of the endosome tubules contain the polarized sorting mechanism responsible for their preferential basolateral distribution.
在极化的MDCK细胞中表达的人转铁蛋白受体（TR）和聚合免疫球蛋白受体（pIgR），即使它们持续进出这些细胞，仍在单独的基底外侧和顶端表面维持稳态的不对称分布。维持这些不对称分布所需的细胞内机制尚未明确。在这里，我们表明TR和pIgR从两个表面内化到一个共同的相互连接的内体区室，该区域包括带有被网格蛋白晶格包被的芽的小管。这些芽产生将TR转运到基底外侧边界的囊泡。这些晶格包含γ-衔接蛋白，并通过布雷菲德菌素A（BFA）处理而分散。由于BFA处理消除了极化MDCK细胞中TR的定向运输，我们提出内体小管的网格蛋白包被区域包含负责其优先基底外侧分布的极化分选机制。
