MRNA去帽
mRNA去帽（mRNA decapping）又称mRNA脱帽，是细胞中将mRNA的5′端帽水解还原成5′磷酸基的反应。真核生物细胞中正活跃翻译的mRNA会与多核糖体结合，5′端帽会与eIF4E、eIF4G等起始因子结合而难与去帽酶接触，在养分缺乏或受病毒感染等逆境中mRNA的翻译可能被抑制，使5′端帽裸露，DCP2等去帽酶可将其5′端帽移除，之后mRNA的5′磷酸基会被RNA外切酶Xrn1等识别，使mRNA被快速降解[1][2] 。去帽与mRNA降解可能皆是在处理小体（P-body）中进行[3]。原核生物中也有类似机制，mRNA的5′端帽则可被RppH等去帽酶水解，将三磷酸基转为单磷酸基，促进RNA被降解[4][5]。
真核生物中具无义突变的mRNA翻译时会触发无义介导的mRNA降解（NMD）途径，将mRNA去帽后降解[6]。一些miRNA也可促进去帽酶与其目标的mRNA结合，进而将其去帽降解[7]。
参考文献[编辑]
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- ^ Sheth, Ujwal; Parker, Roy. Decapping and decay of messenger RNA occur in cytoplasmic processing bodies. Science. 2003-05-02, 300 (5620): 805–808. Bibcode:2003Sci...300..805S. ISSN 1095-9203. PMC 1876714
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- ^ Hsieh, Ping-kun; Richards, Jamie; Liu, Quansheng; Belasco, Joel G. Specificity of RppH-dependent RNA degradation in Bacillus subtilis. Proceedings of the National Academy of Sciences. 22 April 2013, 110 (22): 8864–8869. PMC 3670361 . PMID 23610425. doi:10.1073/pnas.1222670110.
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- ^ Nishihara T, Zekri L, Braun JE, Izaurralde E. miRISC recruits decapping factors to miRNA targets to enhance their degradation.. Nucleic Acids Res. 2013, 41 (18): 8692–705. PMC 3794582 . PMID 23863838. doi:10.1093/nar/gkt619.
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