Clearing Traffic Jams During Protein Translocation Across Membranes.

Protein translocation across membranes is a critical facet of protein biogenesis in compartmentalized cells as proteins synthesized in the cytoplasm often need to traverse across lipid bilayers via proteinaceous channels to reach their final destinations. It is well established that protein biogenesis is tightly linked to various protein quality control processes, which monitor errors in protein folding, modification, and localization. However, little is known about how cells cope with translocation defective polypeptides that clog translocation channels (translocons) during protein translocation. This review summarizes recent studies, which collectively reveal a set of translocon-associated quality control strategies for eliminating polypeptides stuck in protein-conducting channels in the endoplasmic reticulum and mitochondria.

蛋白质跨膜转运是区室化细胞中蛋白质生物发生的一个关键方面，因为在细胞质中合成的蛋白质通常需要通过蛋白质通道穿过脂质双层以到达其最终目的地。众所周知，蛋白质生物发生与各种蛋白质质量控制过程紧密相关，这些过程监测蛋白质折叠、修饰和定位中的错误。然而，对于细胞如何处理在蛋白质转运过程中堵塞转运通道（易位子）的转运缺陷多肽，人们知之甚少。这篇综述总结了近期的研究，这些研究共同揭示了一套与易位子相关的质量控制策略，用于清除在内质网和线粒体中卡在蛋白质传导通道中的多肽。