文档介绍：e to My Molecular Biology Class
Yang Yang(杨洋教授)
Huazhong University of Science and Technology
Ch 12: Mechanisms of transcription
Ch 13: RNA splicing
Ch 14: Translation
Ch 15: The ic code
Part III: Expression of the Genome
CHAPTER 6 RNA Splicing
(第六章 RNA剪接)
Figure 13-1
Primary transcript
外显子
内含子
前mRNA
剪接后的mRNA
Most of the eukaryotic genes are mosaic (嵌合体), consisting of intervening sequences separating the coding sequence(割裂基因)
Exons (外显子): the coding sequences
Introns (内含子) : the intervening sequences
RNA splicing: the process by which introns are removed from the pre-mRNA(从前mRNA中除去内含子的过程)
这个过程将前mRNA转化为成熟RNA,必须绝对精确,避免在外显子连接处缺少或增多哪怕一个核苷酸
Alternative splicing (可变剪接): some pre-mRNAs can be spliced in more than one way , generating alternative mRNAs. 60% of the human genes are spliced in this manner.
有些前mRNA存在不止一种的剪接方式,从而产生不同的mRNA。通过这种方式一个基因可以产生多个多肽产物。通过可变剪接,从一个基因得到的不同产物数量可以从2种到数百甚至数千种。
Outline
RNA剪接的化学基础
剪接体
剪接过程
可变剪接
自剪接内含子
RNA编辑
mRNA转运
Figure 13-2
内含子和外显子交界处的核苷酸序列
5’剪接位点
3’剪接位点
分支位点
5’splice site (5’剪接位点): the exon-intron boundary at the 5’ end of the intron
3’ splice site (3’剪接位点): the exon-intron boundary at the 3’ end of the intron
Branch point site (分支位点): an A close to the 3’ end of the intron, which is followed by a polypyrimidine tract (多聚嘧啶区).