Organization of translocon complexes in ER membranes.
Organization of translocon complexes in ER membranes.
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内质网膜中易位子复合物的组织。
DOI：
10.1042/bst0311253
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发表时间：
2003
影响因子：
3.9
通讯作者：
Kreibich,G
中科院分区：
文献类型：
--
作者：
Nikonov,AV;Kreibich,G
蛋白质在内质网中的转运和N-糖基化是真核细胞正常运作所必需的基本过程。它们是细胞内途径的初始步骤，随后是内膜系统和质膜的分泌蛋白和膜蛋白。这些蛋白质的转位和同时发生的N-糖基化是在一个与膜结合的多聚体相关的大分子机器--转位复合体(TC)上发生的。将TCS分离到内质网的一个分化区域，即粗略内质网，可能会提高膜结合多聚体上蛋白质合成的效率。我们的研究涉及内质网中TCS的组装、功能组织和动力学，以及它们对该细胞器的功能和形态的影响。我们假设，TC形成了定义ER的粗略区域的高阶结构。这些结构在内质网平坦的平面上被缓慢地固定或扩散，可以通过相互连接TCS的mRNAs、细胞骨架元件和/或形成TCS之间连接的假想蛋白质来形成和稳定。我们建立了定量表达GFP-DAD1融合蛋白的M3/18细胞系，并将其功能整合到寡糖转移酶(OST)中。GFP-DAD1可以作为TCS侧向迁移率的报告分子，因为OST与该复合体紧密相关。根据FRAP(荧光漂白后恢复)的测定，GFP-DAD1标记的TCS的横向迁移率比估计的TC大小受到更大的限制，并且可以受到TCS的功能状态的影响。目前，我们正在研究细胞骨架元素在TCS组织中的可能参与。我们的数据表明，微管在TCS的固定中也起到了作用。
Protein translocation in the ER (endoplasmic reticulum) and N-glycosylation are fundamental processes essential for the normal functioning of eukaryotic cells. They are the initial steps in the intracellular pathway that are followed by secretory proteins and membrane proteins of the endomembrane system and the plasma membrane. The translocation and concurrent N-glycosylation of these proteins take place on a large molecular machine, the TC (translocon complex), which is associated with membrane-bound polysomes. Segregation of TCs into a differentiated domain of the ER, the rough ER, may increase the efficiency of protein synthesis on membrane-bound polysomes. Our research is concerned with the assembly, functional organization and dynamics of the TCs in the ER, and their contribution to the functioning and the morphological appearance of this organelle. We hypothesize that the TCs form higher-order structures defining the rough domain of the ER. These structures, which are immobilized or diffuse slowly in the plain of the ER membrane, may be formed and stabilized by mRNAs interconnecting the TCs, by cytoskeletal elements and/or by hypothetical proteins that form links between the TCs. We have established the M3/18 cell line, which expresses the GFP (green fluorescent protein)–Dad1 fusion protein quantitatively and functionally incorporated into the OST (oligosaccharyltransferase). GFP–Dad1 can be used as a reporter molecule for the lateral mobility of the TCs since the OST is tightly associated with the complex. As determined by FRAP (fluorescence recovery after photobleaching), the lateral mobility of GFP–Dad1-tagged TCs was much more restricted than expected from the estimated size of the TC and can be affected by the functional state of the TCs. Currently, we are studying the possible involvement of cytoskeletal elements in the organization of the TCs. Our data suggest that microtubules also play a role in the immobilization of the TCs.