Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, 00014, Finland.
Curr Opin Genet Dev. 2019 Oct;58-59:9-16. doi: 10.1016/j.gde.2019.07.012. Epub 2019 Aug 30.
Many functions of eukaryotic cells are compartmentalized within membrane-bound organelles. One or more cis-encoded signals within a polypeptide sequence typically govern protein targeting to and within destination organelles. Perhaps unexpectedly, organelle targeting does not occur with high specificity, but instead is characterized by considerable degeneracy and inefficiency. Indeed, the same peptide signals can target proteins to more than one location, randomized sequences can easily direct proteins to organelles, and many enzymes appear to traverse different subcellular settings across eukaryotic phylogeny. We discuss the potential benefits provided by flexibility in organelle targeting, with a special emphasis on horizontally transferred and de novo proteins. Moreover, we consider how these new organelle residents can be protected and maintained before they contribute to the needs of the cell and promote fitness.
真核细胞的许多功能都在膜结合细胞器中进行分隔。多肽序列中的一个或多个顺式编码信号通常控制蛋白质靶向到目标细胞器并在其中定位。也许出人意料的是，细胞器靶向并非具有高度特异性，而是具有相当大的简并性和低效性。事实上，相同的肽信号可以将蛋白质靶向到多个位置，随机序列可以轻松地将蛋白质导向细胞器，并且许多酶似乎在真核生物进化过程中穿越不同的亚细胞环境。我们讨论了细胞器靶向灵活性所提供的潜在好处，特别强调了水平转移和从头合成的蛋白质。此外，我们还考虑了这些新的细胞器居民在为细胞需求做出贡献并提高适应性之前如何得到保护和维持。
