Matter K, Bucher K, Hauri H P
Department of Pharmacology, Biocenter of the University of Basel, Switzerland.
EMBO J. 1990 Oct;9(10):3163-70. doi: 10.1002/j.1460-2075.1990.tb07514.x.
Endogenous plasma membrane proteins are sorted from two sites in the human intestinal epithelial cell line Caco-2. Apical proteins are transported from the Golgi apparatus to the apical domain along a direct pathway and an indirect pathway via the basolateral membrane. In contrast, basolateral proteins never appear in the apical plasma membrane. Here we report on the effect of the microtubule-active drug nocodazole on the post-synthetic transport and sorting of plasma membrane proteins. Pulse-chase radiolabeling was combined with domain-specific cell surface assays to monitor the appearance of three apical and one basolateral protein in plasma membrane domains. Nocodazole was found to drastically retard both the direct transport of apical proteins from the Golgi apparatus and the indirect transport (transcytosis) from the basolateral membrane to the apical cell surface. In contrast, neither the transport rates of the basolateral membrane nor the sorting itself were significantly affected by the nocodazole treatment. We conclude that an intact microtubular network facilitates, but is not necessarily required for, the transport of apical membrane proteins along the two post-Golgi pathways to the brush border.
内源性质膜蛋白在人肠上皮细胞系Caco-2中的两个位点进行分选。顶端蛋白从高尔基体沿着直接途径和经由基底外侧膜的间接途径转运至顶端结构域。相反，基底外侧蛋白从未出现在顶端质膜中。在此，我们报告微管活性药物诺考达唑对质膜蛋白合成后运输和分选的影响。脉冲追踪放射性标记与结构域特异性细胞表面分析相结合，以监测三种顶端蛋白和一种基底外侧蛋白在质膜结构域中的出现情况。发现诺考达唑极大地阻碍了顶端蛋白从高尔基体的直接运输以及从基底外侧膜到顶端细胞表面的间接运输（转胞吞作用）。相反，基底外侧膜的运输速率和分选本身均未受到诺考达唑处理的显著影响。我们得出结论，完整的微管网络促进了顶端膜蛋白沿两条高尔基体后途径向刷状缘的运输，但并非必需。
