Groothuis Tom A M, Dantuma Nico P, Neefjes Jacques, Salomons Florian A
Department of Cell and Molecular Biology, The Medical Nobel Institute, Karolinska Institutet, Von Eulers väg 3, S-17177, Stockholm, Sweden.
Cell Div. 2006 Sep 28;1:21. doi: 10.1186/1747-1028-1-21.
The polypeptide ubiquitin is used in many processes as different as endocytosis, multivesicular body formation, and regulation of gene transcription. Conjugation of a single ubiquitin moiety is typically used in these processes. A polymer of ubiquitin moieties is required for tagging proteins for proteasomal degradation. Besides its role in protein degradation, ubiquitin is also engaged as mono- or polymer in intracellular signalling and DNA repair. Since free ubiquitin is present in limiting amounts in cells, changes in the demands for ubiquitin in any of these processes is likely to indirectly affect other ubiquitin modifications. For example, proteotoxic stress strongly increases poly-ubiquitylated proteins at the cost of mono-ubiquitylated histones resulting in chromatin remodelling and altered transcription. Here we discuss the interconnection between ubiquitin-dependent processes and speculate on the functional significance of the ubiquitin equilibrium as a signalling route translating cellular stress into molecular responses.
多肽泛素在许多不同的过程中发挥作用，如内吞作用、多泡体形成和基因转录调控。在这些过程中通常使用单个泛素部分的缀合。泛素部分的聚合物是标记蛋白质以便蛋白酶体降解所必需的。除了在蛋白质降解中的作用外，泛素还作为单体或聚合物参与细胞内信号传导和DNA修复。由于游离泛素在细胞中的含量有限，这些过程中任何一个对泛素需求的变化都可能间接影响其他泛素修饰。例如，蛋白毒性应激会以单泛素化组蛋白为代价强烈增加多泛素化蛋白，导致染色质重塑和转录改变。在这里，我们讨论泛素依赖性过程之间的相互联系，并推测泛素平衡作为将细胞应激转化为分子反应的信号途径的功能意义。
