异常mRNA的向细胞质处理体
1Department of Molecular and Cellular Biology, University of Arizona, Tucson, 85721, USA.
Cell
|June 17, 2006
概括
在酵母中,无意中介衰变 (NMD) 将有缺陷的mRNA向P体进行降解. 像Upf1p这样的特定蛋白质促进了这种向和随后的mRNA衰变,区分异常与正常的转录.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 细胞生物学 细胞生物学
背景情况:
- 无意中介衰变 (NMD) 是真核生物中的一个关键的mRNA监测途径.
- NMD识别和降解含有过早终止子 (PTC) 的信使RNA (mRNA).
- 这个过程通过消除异常转录来确保细胞质量控制.
研究的目的:
- 调查酵母P体在NMD途径中的作用.
- 阐明关键NMD因子 (Upf1p,Upf2p,Upf3p) 在mRNA向和降解中的特定功能.
- 为NMD机制提出一个改进的模型.
主要方法:
- 利用酵母作为一个模型生物体.
- 研究了含有PTC的mRNAs到P体的局部化.
- 评估了在NMD中对Upf蛋白和Upf1p ATPase活性的要求.
- 区分了Upf蛋白在P体向与切割中的作用.
主要成果:
- 酵母NMD将含有PTC的mRNA向P体.
- Upf1p足以将mRNA向P体.
- Upf2p和Upf3p参与触发P体局部化下游的断层.
- Upf1p ATPase活性对于NMD后P体向至关重要.
- Upf1p可以将正常的mRNA向P体,而不会促进降解.
结论:
- 提出了NMD的两步模型,区分正常和异常mRNAs.
- P体向是NMD的一个早期步骤,由Upf1p介导.
- 涉及Upf2p,Upf3p和Upf1p ATPase活性的后续步骤导致异常mRNAs的降解.
相关概念视频
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Cis-acting Elements involved in mRNA stability
Cis-acting Elements involved in mRNA stability
Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
Nonsense-mediated mRNA Decay
The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...


