Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
Curr Opin Cell Biol. 2022 Apr;75:102071. doi: 10.1016/j.ceb.2022.02.005. Epub 2022 Mar 17.
The majority of cellular proteins are targeted to organelles. Cytosolic ribosomes produce these proteins as precursors with cleavable or non-cleavable targeting sequences that direct them to receptor proteins on the organelle surface. Multiple targeting factors ensure cellular sorting of the precursor proteins. In co-translational protein import, the ribosome-nascent chain complex is transported to the organellar protein translocase to couple protein synthesis and protein import. In post-translational mode, targeting factors like molecular chaperones guide the precursor proteins from ribosomes to the cell organelle. Defects in protein targeting and import cause mistargeting of proteins to different cellular compartments and challenge the balance of cellular proteostasis. Specific dislocases and degradation machineries remove such mislocalized proteins from the membrane to allow retargeting or their proteasomal turnover. In this review, we discuss targeting and quality control factors that ensure fidelity of protein targeting to mitochondria.
大多数细胞蛋白都被靶向到细胞器中。细胞质核糖体将这些蛋白质作为前体合成，前体带有可切割或不可切割的靶向序列，将其导向细胞器表面的受体蛋白。多种靶向因子确保了前体蛋白的细胞分拣。在共翻译蛋白导入过程中，核糖体-新生链复合物被转运到细胞器蛋白移位酶，以偶联蛋白合成和蛋白导入。在后翻译模式中，靶向因子（如分子伴侣）将前体蛋白从核糖体引导到细胞器。蛋白靶向和导入的缺陷会导致蛋白错误靶向到不同的细胞区室，并挑战细胞蛋白稳态的平衡。特定的脱位酶和降解机制将这些错误定位的蛋白质从膜上移除，以允许重新靶向或蛋白酶体降解。在这篇综述中，我们讨论了确保蛋白靶向到线粒体的保真度的靶向和质量控制因子。
