Matter K, Brauchbar M, Bucher K, Hauri H P
Department of Pharmacology, University of Basel, Switzerland.
Cell. 1990 Feb 9;60(3):429-37. doi: 10.1016/0092-8674(90)90594-5.
We studied the postsynthetic sorting of endogenous plasma membrane proteins in a polarized epithelial cell line, Caco-2. Pulse-chase radiolabeling was combined with domain-specific cell surface assays to monitor the arrival of three apical and one basolateral protein at the apical and basolateral cell surface. Apical proteins were inserted simultaneously into both membrane domains. The fraction targeted to the basolateral domain was different for the three apical proteins and was subsequently sorted to the apical domain by transcytosis at different rates. In contrast, a basolateral protein was found in the basolateral membrane only. Thus, sorting of plasma membrane proteins occurred from two sites: the Golgi apparatus and the basolateral membrane. These data explain apparently conflicting results of earlier studies.
我们研究了极化上皮细胞系Caco-2中内源性质膜蛋白的合成后分选过程。脉冲追踪放射性标记与区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到达顶端和基底外侧细胞表面的情况。顶端蛋白同时插入两个膜区域。三种顶端蛋白靶向基底外侧区域的比例不同，随后通过不同速率的转胞吞作用被分选到顶端区域。相比之下，一种基底外侧蛋白仅存在于基底外侧膜中。因此，质膜蛋白的分选发生在两个部位：高尔基体和基底外侧膜。这些数据解释了早期研究中明显相互矛盾的结果。
