武汉大学生命科学学院：《分子生物学》（英文版）Part III：Expression of the Genome CHAPTER13 RNA Splicing

Molecular Biology of the Gene, 5/E Watson et al (2004) Part I: Chemistry and Genetics Part Ii: Maintenance of the Genome Part III: Expression of the Genome Part IV: Regulation Part v: methods 4/3/05 肃博来字

Molecular Biology of the Gene, 5/E --- Watson et al. (2004) Part I: Chemistry and Genetics Part II: Maintenance of the Genome Part III: Expression of the Genome Part IV: Regulation Part V: Methods 4/3/05

ch 12: Mechanisms of Transcription 口ch13: RNA Splicing ch 14: Translation ch 15: The Genetic code 4/3/05 刻博来字 Wuhan Universit

Ch 12 : Mechanisms of Transcription Ch 13 : RNA Splicing Ch 14 : Translation Ch 15 : The Genetic code 4/3/05

Molecular Biology course CHAPTER 13 RNA Splicing @或属来字 Wuhan Universi

CHAPTER 13 RNA Splicing •Molecular Biology Course

promoter region itron 1 genomIc DNA exon 1 transcription noncoding 5 leader reqion 4 pre-mRNA 5 3 Primary transcript splIcing spliced mRNA 5匚 3 1234 Figure 13-1

Figure 13-1 Primary transcript

Most of the eukaryotic genes are osage(嵌合体), consisting of intervening sequences separating the coding sequence Exons(外显子): the coding sequences 工 introns(内含子): the intervening sequences a RNA splicing: the process by which introns are removed from the pre mRNA Alternative splicing(可变剪接):some pre-mRNAs can be spliced in more than one way, generating alternative mRNAS. 60%o of the human genes are spliced in this manner

Most of the eukaryotic genes are mosaic (嵌合体), consisting of intervening sequences separating the coding sequence ◼ 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. ◼ 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

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 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