文档介绍：In prokaryotes, transcription produces a nearly exact mRNA copy of the DNA, and the transcript is immediately translated into protein. In eukaryotes, a series of modifications occur to mRNA during and after transcription.
在原核生物中,转录产生的mRNA几乎是DNA的准确拷贝,并且这一转录产物会立即被转译成蛋白质。在真核生物中,转录时以及转录后会对mRNA进行一系列修饰。
Chapter 5 mRNA Modifications in Eukaryotes第5章真核生物mRNA的修饰
Capping
Polyadenylation
Splicing
mRNA Editing
Experiments
加帽
聚腺苷酸化
剪接
mRNA编辑
实验研究
Chapter 5 mRNA Modifications in Eukaryotes第5章真核生物mRNA的修饰
Capping / 加帽
An mRNA that has been transcribed but is not yet ready for translation is called a pre-mRNA, or a primary transcript.
Capping is the process of adding a derivative of guanine nucleotide to the 5’ end of the pre-mRNA.
一条已经转录出来但还没有准备好用于转译的mRNA称为前体mRNA或初级转录本。
加帽是在前体mRNA的5’末端加上一个鸟嘌呤核苷酸衍生物的过程。
Structure of the cap / 帽的结构
5’-3’ phospho-
diester bond
5’-5’ triphosphate bond
RNA polymerase II
Discussed in Chapter 4
Capping takes place quite early.
5’-Cap
RNA polymerase II
RNA
DNA
Capping process / 加帽过程
CTD: C-terminal domain
RNA polymerase II
DNA
Methyl transferase
Guanylyl
transferase
RNA triphosphatase
Functions of the cap structure帽结构的功能
1. Helps prevent degradation 帮助防止降解
2. Helps transport into cytoplasm 帮助转运到细胞质中
3. Enhances translation / 增强转译
4. Helps remove the first intron 帮助去除第一个内含子
1. Helps prevent degradation帮助防止降解
RNase
RNase
5’-5’ triphosphate bond
5’-3’ phospho
diester bond
5’-3’ phospho
diester bond