Transferrin receptor polarity and recycling accuracy in "tight" and "leaky" strains of Madin-Darby canine kidney cells.
Transferrin receptor polarity and recycling accuracy in "tight" and "leaky" strains of Madin-Darby canine kidney cells.
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DOI：
10.1083/jcb.103.5.1767
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发表时间：
1986-11
期刊：
影响因子：
--
通讯作者：
Simons K
中科院分区：
文献类型：
--
作者：
Fuller SD;Simons K
我们鉴定了上皮性Madin-Darby犬肾(MDCK)细胞系中转铁蛋白受体的极性。该受体存在于每个细胞约165,000个拷贝中，在与MR 90,000的SDS凝胶电泳中以扩散带的形式迁移，在中性pH约为2 NM时显示出对去铁转铁蛋白的解离常数，并且在几乎所有的细胞中都是活性的。用转铁蛋白介导的~(55)Fe摄取检测滤过性培养的MDCK细胞活性转铁蛋白受体的极性。对于高阻品系I MDCK细胞(通常大于2,000欧姆×cm2)，基侧与顶端受体的比例约为800：1，对于低阻品系II细胞(通常小于350欧姆×cm2)，约为300：1。结合形态计量学数据，这表明这两个菌株之间的抗性差异并不反映在细胞表面极性的显着差异上。我们使用过滤培养的MDCK细胞中转铁蛋白受体的循环来评估在内吞过程中对基侧蛋白进行分类的准确性。监测在基底外侧表面应用55Fe和125I标记的转铁蛋白后顶端释放的125I标记转铁蛋白的量，可以灵敏地分析受体从内体到质膜循环过程中分选的准确性。转铁蛋白受体分选的准确性(大于99.88%)在内小体和质膜之间的单个运输周期内足以维持细胞的高水平极性。
We have characterized the polarity of the transferrin receptor in the epithelial Madin-Darby canine kidney (MDCK) cell line. The receptor is present in approximately 165,000 copies per cell, migrates as a diffuse band upon SDS gel electrophoresis with Mr 90,000, displays a dissociation constant for diferritransferrin at neutral pH of approximately 2 nM, and is active in essentially all of the cells of the population. Transferrin-mediated 55Fe uptake was used to measure the polarity of active transferrin receptors in filter-grown MDCK cells. The ratio of basolateral to apical receptors was approximately 800:1 for the high resistance strain I MDCK cells (typically greater than 2,000 ohm X cm2) and approximately 300:1 for the lower resistance strain II cells (less than 350 ohm X cm2). In combination with morphometric data this shows that a difference in resistance between these two strains is not reflected in a significant difference in cell surface polarity. We used the recycling of transferrin receptor in filter-grown MDCK cells to evaluate the accuracy of the sorting of a basolateral protein during endocytosis. Monitoring the amount of apically released 125I-labeled transferrin after application of 55Fe- and 125I-labeled transferrin to the basolateral surface provided a sensitive assay of the accuracy of sorting during recycling of the receptor from endosomes to the plasma membrane. The accuracy of transferrin receptor sorting (greater than 99.88%) during a single cycle of transit between the endosome and the plasma membrane is sufficient to maintain the high level of polarity of the cell.