Apical plasma membrane proteins and endolyn-78 travel through a subapical compartment in polarized WIF-B hepatocytes.
Apical plasma membrane proteins and endolyn-78 travel through a subapical compartment in polarized WIF-B hepatocytes.
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顶质质膜蛋白和Endolyn-78穿过极化Wif-B肝细胞中的副室。
DOI：
10.1083/jcb.141.1.115
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发表时间：
1998-04-06
期刊：
影响因子：
--
通讯作者：
Hubbard AL
中科院分区：
文献类型：
--
作者：
Ihrke G;Martin GV;Shanks MR;Schrader M;Schroer TA;Hubbard AL
我们研究了极化肝wi - b细胞中三种根尖质膜蛋白（PM）的基底侧向根尖转胞作用，并将其与基底侧循环膜蛋白的内噬运输进行了比较。我们使用抗体标记活细胞表面的基底外侧蛋白质群，然后通过间接免疫荧光跟踪其在37°C下的运输。根尖蛋白氨基肽酶N、5′核苷酸酶和聚合IgA受体被有效地转酶化。通过向胆管样空间显微注射二抗和EM研究证实了对根尖PM的递送。在获得其顶端稳态分布之前，被运输的抗体在根尖下腔室中积累，在EM下具有独特的管状泡状外观。相反，针对asialalglycocoprotein和甘露糖-6-磷酸受体的抗体或针对溶酶体膜蛋白lgp120的抗体分别分布在核内体或溶酶体中，而不会在根尖下区域积累。然而，内溶体/溶酶体蛋白内溶素-78的途径部分类似于经细胞分裂途径，因为在进入溶酶体之前，在根尖下腔室中发现了抗内溶素-78抗体。我们的研究结果表明，在wi - b细胞中，经细胞分裂的分子通过一个根尖下腔室，作为到达该腔室的基底侧内噬膜蛋白亚群的第二个分选位点。
We studied basolateral-to-apical transcytosis of three classes of apical plasma membrane (PM) proteins in polarized hepatic WIF-B cells and then compared it to the endocytic trafficking of basolaterally recycling membrane proteins. We used antibodies to label the basolateral cohort of proteins at the surface of living cells and then followed their trafficking at 37°C by indirect immunofluorescence. The apical PM proteins aminopeptidase N, 5′nucleotidase, and the polymeric IgA receptor were efficiently transcytosed. Delivery to the apical PM was confirmed by microinjection of secondary antibodies into the bile canalicular-like space and by EM studies. Before acquiring their apical steady-state distribution, the trafficked antibodies accumulated in a subapical compartment, which had a unique tubulovesicular appearance by EM. In contrast, antibodies to the receptors for asialoglycoproteins and mannose-6-phosphate or to the lysosomal membrane protein, lgp120, distributed to endosomes or lysosomes, respectively, without accumulating in the subapical area. However, the route taken by the endosomal/lysosomal protein endolyn-78 partially resembled the transcytotic pathway, since anti–endolyn-78 antibodies were found in a subapical compartment before delivery to lysosomes. Our results suggest that in WIF-B cells, transcytotic molecules pass through a subapical compartment that functions as a second sorting site for a subset of basolaterally endocytosed membrane proteins reaching this compartment.