Regulated motion of glycoproteins revealed by direct visualization of a single cargo in the endoplasmic reticulum
Regulated motion of glycoproteins revealed by direct visualization of a single cargo in the endoplasmic reticulum
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DOI：
10.1083/jcb.200704078
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发表时间：
2008-01-14
影响因子：
7.8
通讯作者：
Wada, Ikuo
中科院分区：
文献类型：
--
作者：
Nagaya, Hisao;Tamura, Taku;Wada, Ikuo
内质网（ER）中货物蛋白的质量受其折叠过程中运动的影响。为了了解如何在ER中调节分泌性货物蛋白的扩散，我们使用荧光成像/波动分析直接分析单个货物分子的运动。我们发现，除了两个N-聚糖的货物显着改变其扩散的瞬时结合膜组件，被限制在高渗透压。通过同时观察单个货物和ER出口位点（ERES），我们可以排除ERES作为结合位点。值得注意的是，肌动蛋白细胞骨架所需的瞬时结合。这些结果为高渗诱导的货物固定化提供了分子基础，货物固定化依赖于多个位点的糖基化而不是正确折叠的完成。我们建议，ER腔中的分泌性糖蛋白的扩散是从细胞质控制，以减少聚集的机会。
The quality of cargo proteins in the endoplasmic reticulum (ER) is affected by their motion during folding. To understand how the diffusion of secretory cargo proteins is regulated in the ER, we directly analyze the motion of a single cargo molecule using fluorescence imaging/fluctuation analyses. We find that the addition of two N-glycans onto the cargo dramatically alters their diffusion by transient binding to membrane components that are confined by hyperosmolarity. Via simultaneous observation of a single cargo and ER exit sites (ERESs), we could exclude ERESs as the binding sites. Remarkably, actin cytoskeleton was required for the transient binding. These results provide a molecular basis for hypertonicity-induced immobilization of cargo, which is dependent on glycosylation at multiple sites but not the completion of proper folding. We propose that diffusion of secretory glycoproteins in the ER lumen is controlled from the cytoplasm to reduce the chances of aggregation.