Panasenko Olesya O
Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics of Geneva - University Medical Center, Faculty of Medicine, University of Geneva Geneva, Switzerland.
Front Genet. 2014 May 19;5:141. doi: 10.3389/fgene.2014.00141. eCollection 2014.
Cotranslational quality control (QC) is the mechanism by which the cell checks the integrity of newly synthesized proteins and mRNAs. In the event of mistakes these molecules are degraded. The Ccr4-Not complex has been proposed to play a role in this process. It contains both deadenylation and ubiquitination activities, thus it may target both aberrant proteins and mRNAs. Deadenylation is the first step in mRNA degradation. In yeast it is performed by the Ccr4 subunit of the Ccr4-Not complex. Another complex subunit, namely Not4, is a RING E3 ligase and it provides the ubiquitination activity of the complex. It was found associated with translating ribosomes. Thus, it has been suggested that Not4 is involved in ribosome-associated ubiquitination and degradation of aberrant peptides. However, several other E3 ligases have been associated with peptide ubiquitination on the ribosome and the relevance of Not4 in this process remains unclear. In this review we summarize the recent data and suggest a role for Not4 in cotranslational protein QC.
共翻译质量控制（QC）是细胞检查新合成蛋白质和mRNA完整性的机制。如果出现错误，这些分子会被降解。有人提出Ccr4-Not复合物在这个过程中发挥作用。它同时具有去腺苷酸化和泛素化活性，因此它可能针对异常蛋白质和mRNA。去腺苷酸化是mRNA降解的第一步。在酵母中，这是由Ccr4-Not复合物的Ccr4亚基完成的。另一个复合物亚基，即Not4，是一种RING E3连接酶，它提供复合物的泛素化活性。人们发现它与正在翻译的核糖体相关联。因此，有人认为Not4参与核糖体相关的泛素化和异常肽的降解。然而，其他几种E3连接酶也与核糖体上的肽泛素化有关，Not4在这个过程中的相关性仍不清楚。在这篇综述中，我们总结了最近的数据，并提出Not4在共翻译蛋白质质量控制中的作用。
