CHATER 13 RNA Splicing Topic 1: THE CHEMISTRY OF RNA SPLICING
Topic 1 : THE CHEMISTRY OF RNA SPLICING CHAPTER 13 RNA Splicing
E Sequences within the rNA Determine Where Splicing R Occurs The borders between introns and exons are marked by specific nucleotide sequences within the pre-MRNAs
Sequences within the RNA Determine Where Splicing Occurs The chemistry of RNA splicing The borders between introns and exons are marked by specific nucleotide sequences within the pre-mRNAs
5 exon intron 3 exon 5|AGGU公AGU e.。000。● A…[ Py tract])AGG…3 5 splice site branch site 3 splice site The consensus sequences for human Figure 13-2 Copyright C 2004 Pearson Education, Inc, publishing as Benjamin Cummings
Figure 13-2 The consensus sequences for human
5sp| lice site(5剪接位点): the exon intron boundary at the 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(分枝位点)anA close to the 3'end of the intron, which is followed by a polypyrimidine tract(Py tract)
◼ 5’splice site (5’剪接位点): the exonintron 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 (分枝位点): an A close to the 3’ end of the intron, which is followed by a polypyrimidine tract (Py tract)
E The intron is removed in a Form called a lariat(套马索)as o the Flanking Exons are joined Two successive transesterification: 2 Step 1: The OH of the conserved A o at the branch site attacks the phosphoryl group of the conserved G in the 5, splice site. g As a result, the 57 exon is released and the 5-end of the 2. intron forms a three-way 日 junction structure
The intron is removed in a Form Called a Lariat (套马索) as the Flanking Exons are joined Two successive transesterification: Step 1: The OH of the conserved A at the branch site attacks the phosphoryl group of the conserved G in the 5’ splice site. As a result, the 5’ exon is released and the 5’-end of the intron forms a three-way junction structure. The chemistry of RNA splicing