Lejeune Fabrice, Maquat Lynne E
Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, Rochester, New York, USA.
Curr Opin Cell Biol. 2005 Jun;17(3):309-15. doi: 10.1016/j.ceb.2005.03.002.
Nonsense-mediated mRNA decay (NMD) generally involves nonsense codon recognition by translating ribosomes at a position approximately 25 nts upstream of a splicing-generated exon junction complex of proteins. As such, NMD provides a means to degrade abnormal mRNAs that encode potentially deleterious truncated proteins. Additionally, an estimated one-third of naturally occurring, alternatively spliced mRNAs is also targeted for NMD. Given the extraordinary frequency of alternative splicing together with data indicating that naturally occurring transcripts other than alternatively spliced mRNAs are likewise targeted for NMD, it is believed that mammalian cells routinely utilize NMD to achieve proper levels of gene expression.
无义介导的mRNA降解（NMD）通常涉及核糖体在蛋白质剪接产生的外显子连接复合体上游约25个核苷酸处识别无义密码子。因此，NMD提供了一种降解异常mRNA的方式，这些异常mRNA编码可能有害的截短蛋白。此外，估计约三分之一的自然发生的可变剪接mRNA也被NMD靶向。鉴于可变剪接的频率极高，以及数据表明除可变剪接mRNA之外的自然发生的转录本同样被NMD靶向，人们认为哺乳动物细胞通常利用NMD来实现适当水平的基因表达。
