Chapter 22 Nuclear splicing 莘大
Chapter 22 Nuclear splicing
22.1 Introduction 22.2 Nuclear splice junctions are short sequences 22.3 Splice junctions are read in pairs 22. 4 Nuclear splicing proceeds through a lariat 22.5 snRNAS are required for splicing 22.6 UI snRNP initiates splicing 22.7 The E complex can be formed in alternative ways 22. 8 5 snRNPs form the spliceosome 22.9 An alternative splicing apparatus uses different snRNP 22 10 Group II introns autosplice via lariat formation 22. 11 Alternative splicing involves differential use of splice junctions 22 12 CiS-splicing and trans-splicing reactions 22 13 Yeast tRNA splicing involves cutting and rejoining 22 14 The unfolded protein response is related to tRNA splicing 22. 15 The 3c ends of poll and pollll transcripts are generated by termination 22.16 The 3c ends of mRNAS are generated by cleavage 22 17 Cleavage of the 3c end may require a small rNA 22.18 Production of rRNA requires cleavage and modification events 22 19 Small RNAs are required for rRNA processing 消当
22.1 Introduction 22.2 Nuclear splice junctions are short sequences 22.3 Splice junctions are read in pairs 22.4 Nuclear splicing proceeds through a lariat 22.5 snRNAs are required for splicing 22.6 U1 snRNP initiates splicing 22.7 The E complex can be formed in alternative ways 22.8 5 snRNPs form the spliceosome 22.9 An alternative splicing apparatus uses different snRNPs 22.10 Group II introns autosplice via lariat formation 22.11 Alternative splicing involves differential use of splice junctions 22.12 cis-splicing and trans-splicing reactions 22.13 Yeast tRNA splicing involves cutting and rejoining 22.14 The unfolded protein response is related to tRNA splicing 22.15 The 3¢ ends of polI and polIII transcripts are generated by termination 22.16 The 3¢ ends of mRNAs are generated by cleavage 22.17 Cleavage of the 3¢ end may require a small RNA 22.18 Production of rRNA requires cleavage and modification events 22.19 Small RNAs are required for rRNA processing
21.1Introduction RNA Splicing is the process of excising the sequences in RNa that correspond to introns, so that the sequences corresponding to exons are connected into a continuous mrNA pre-mRNA heterogeneous nuclear RNA (hnRNA) hnRNP 消当
RNA splicing is the process of excising the sequences in RNA that correspond to introns, so that the sequences corresponding to exons are connected into a continuous mRNA. pre-mRNA heterogeneous nuclear RNA (hnRNA). hnRNP 21.1 Introduction
22. Introduction Figure 22.1 hnRNP hnrna 200A 40S exists as a ribonuclear otein particle 500-800 bases RNA organized as Core proteins (-30-40 KD) a series of b A1A2日1日2C1c2 eads 请莘大
Figure 22.1 hnRNA exists as a ribonucleopr otein particle organized as a series of beads. 22.1 Introduction
xon bren I Exam2余ton2om3nnEo0年mto(n5 22.1 Introduction WNF A i Figure 22.2 RNA is modified in the nucleus by Endd'modrfication additions to the5￠and3￠ ends and by splicing to remove the introns. The NUCLEUS splicing event requires breakage of the exon-intron ransport junctions and joining of the ends of the exons the Transation: CYTOPLASM expanded illustration shows the principle schematically but not the actual order of exon events. Mature mRNA is Exon-intron junctions are b ken transported through nuclear pores to the cytoplasm. Exons are joined where it is translated 请莘大
Figure 22.2 RNA is modified in the nucleus by additions to the 5￠ and 3￠ ends and by splicing to remove the introns. The splicing event requires breakage of the exon-intron junctions and joining of the ends of the exons; the expanded illustration shows the principle schematically, but not the actual order of events. Mature mRNA is transported through nuclear pores to the cytoplasm, where it is translated. 22.1 Introduction
22.2 Nuclear splice junctions are interchangeable but are read in pairs GT-AG rule describes the presence of these constant dinucleotides at the first two and last two positions of introns of nuclear genes Splice sites are the sequences immediately surrounding the exon-intron boundaries 消当
GT-AG rule describes the presence of these constant dinucleotides at the first two and last two positions of introns of nuclear genes. Splice sites are the sequences immediately surrounding the exon-intron boundaries. 22.2 Nuclear splice junctions are interchangeable but are read in pairs
22.2 Nuclear splice junctions are interchangeable but are read in pairs Left (5)ste Right(③)ste Exoe64⑤7310010462g4l63 12PyN C65A10F10JN EXon Intron Figure 22. 3 The ends of nuclear introns are defined by the gt-ag rule 消当
Figure 22.3 The ends of nuclear introns are defined by the GT-AG rule 22.2 Nuclear splice junctions are interchangeable but are read in pairs
22.2 Nuclear splice junctions are interchangeable but are read in pairs Correct splicing removes 3 introns by pairwise reoognit ion of the juncions Figure 22.4 Splicing Junctions are Pairing of wrong junctions would remove exons as well as introns, but aberrant products are not found recognIz red only in the correct pairwise GGU combinations 请莘大
Figure 22.4 Splicing junctions are recognized only in the correct pairwise combinations. 22.2 Nuclear splice junctions are interchangeable but are read in pairs
22.2 Nuclear splice junctions are interchangeable but are The vector cont ains two exons that are spliced together in the transcrip promotery 5' splice junction! 3 splice junction Figure 2.20 A special exon int ron exon splicing vector is used for exon trapping. If an A genomic fragment is inserted into the intron, any exon in the exon is present in the fragment will be found in the RNA Genomic fragment genomic fragment, its intron exon intron sequence will be Insert into recovered in the cloning site cytoplasmic RNA, but if the genomic fragment consists exon exon intron solely of an intron Transcrip splicing 消当
Figure 2.20 A special splicing vector is used for exon trapping. If an exon is present in the genomic fragment, its sequence will be recovered in the cytoplasmic RNA, but if the genomic fragment consists solely of an intron, 22.2 Nuclear splice junctions are interchangeable but are read in pairs
Gene =5.6 kb 22.2 Nuclear splice junctions 1■2■345l67 are interchangeable but are read in pairs ↓ 1.1kb Figure 22.5 Northern pRimary transcript(5.5 kb blotting of nuclear RNA with an ovomucoid pI robe identifies discrete Lacks introns 5&6 precursors to mRNA. The contents of the more Lacks introns 4.5.6.&7 prominent bands are Contains only intron 3 indicated. Photograph kindly provided by bert OMalley mRNA(1. 1 kb) 消当
Figure 22.5 Northern blotting of nuclear RNA with an ovomucoid probe identifies discrete precursors to mRNA. The contents of the more prominent bands are indicated. Photograph kindly provided by Bert O'Malley. 22.2 Nuclear splice junctions are interchangeable but are read in pairs