RNA splicing - wikipedia RNA splicing This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. ( December 2016 ) In molecular biology, splicing is the editing of the nascent precursor messenger RNA ( pre-mRNA ) transcript into a mature messenger RNA ( mRNA ). After splicing, introns are removed and exons are joined together ( ligated ). For nuclear - encoded genes, splicing takes place within the nucleus either during or immediately after transcription. For those eukaryotic genes that contain introns, splicing is usually required in order to create an mRNA molecule that can be translated into protein. For many eukaryotic introns, splicing is carried out in a series of reactions which are catalyzed by the spliceosome, a complex of snRNPs. Self - splicing introns, or ribozymes capable of catalyzing their own excision from their parent RNA molecule, also exist. Contents 1 Splicing pathways 1.1 Spliceosomal 1.1. 1 Introns 1.1. 2 Formation and activity 1.2 Self - splicing 1.3 tRNA splicing 2 Evolution 3 Biochemical mechanism 4 Alternative splicing 5 Splicing response to DNA damage 6 Experimental manipulation of splicing 7 Splicing errors and variation 8 Protein splicing 9 See also 10 References 11 External links Splicing pathways Several methods of RNA splicing occur in nature ; the type of splicing depends on the structure of the spliced intron and the catalysts required for splicing to occur. Spliceosomal Introns The word intron is derived from the term intervening sequence, that is, a segment of DNA that `` intervenes '' between two exons of a gene. The term intron refers to both the DNA sequence within a gene and the corresponding sequence in the unprocessed RNA transcript. As part of the RNA processing pathway, introns are removed by RNA splicing either shortly after or concurrent with transcription. Introns are found in the genes of most organisms and many viruses. They can be located in a wide range of genes, including those that generate proteins, ribosomal RNA ( rRNA ), and transfer RNA ( tRNA ). Spliceosomal introns often reside within the sequence of eukaryotic protein - coding genes. Within the intron, a donor site ( 5 ' end of the intron ), a branch site ( near the 3 ' end of the intron ) and an acceptor site ( 3 ' end of the intron ) are required for splicing. The splice donor site includes an almost invariant sequence GU at the 5 ' end of the intron, within a larger, less highly conserved region. The splice acceptor site at the 3 ' end of the intron terminates the intron with an almost invariant AG sequence. Upstream ( 5 ' - ward ) from the AG there is a region high in pyrimidines ( C and U ), or polypyrimidine tract. Further upstream from the polypyrimidine tract is the branchpoint, which includes an adenine nucleotide involved in lariat formation. The consensus sequence for an intron ( in IUPAC nucleic acid notation ) is : G-G - ( cut ) - G-U-R-A-G-U ( donor site )... intron sequence... Y-U-R-A-C ( branch sequence 20 - 50 nucleotides upstream of acceptor site )... Y - rich - N-C-A-G - ( cut ) - G ( acceptor site ). However, it is noted that the specific sequence of intronic splicing elements and the number of nucleotides between the branchpoint and the nearest 3 ' acceptor site affect splice site selection. Also, point mutations in the underlying DNA or errors during transcription can activate a cryptic splice site in part of the transcript that usually is not spliced. This results in a mature messenger RNA with a missing section of an exon. In this way, a point mutation, which might otherwise affect only a single amino acid, can manifest as a deletion or truncation in the final protein. Simple illustration of exons and introns in pre-mRNA Formation and activity Splicing is catalyzed by the spliceosome, a large RNA - protein complex composed of five small nuclear ribonucleoproteins ( snRNPs, pronounced ' snurps ' ). Assembly and activity of the spliceosome occurs during transcription of the pre-mRNA. The RNA components of snRNPs interact with the intron and are involved in catalysis. Two types of spliceosomes have been identified ( major and minor ) which contain different snRNPs. The major spliceosome splices introns containing GU at the 5 ' splice site and AG at the 3 ' splice site. It is composed of the U1, U2, U4, U5, and U6 snRNPs and is active in the nucleus. In addition, a number of proteins including U2 small nuclear RNA auxiliary factor 1 ( U2AF35 ), U2AF2 ( U2AF65 ) and SF1 are required for the assembly of the spliceosome. The spliceosome forms different complexes during the splicing process : Complex E The U1 snRNP binds to the GU sequence at the 5 ' splice site of an intron ; Splicing factor 1 binds to the intron branch point sequence ; U2AF1 binds at the 3 ' splice site of the intron ; U2AF2 binds to the polypyrimidine tract ; Complex A ( pre-spliceosome ) The U2 snRNP displaces SF1 and binds to the branch point sequence and ATP is hydrolyzed ; Complex B ( pre-catalytic spliceosome ) The U5 / U4 / U6 snRNP trimer binds, and the U5 snRNP binds exons at the 5 ' site, with U6 binding to U2 ; Complex B * The U1 snRNP is released, U5 shifts from exon to intron, and the U6 binds at the 5 ' splice site ; Complex C ( catalytic spliceosome ) U4 is released, U6 / U2 catalyzes transesterification, making the 5 ' - end of the intron ligate to the A on intron and form a lariat, U5 binds exon at 3 ' splice site, and the 5 ' site is cleaved, resulting in the formation of the lariat ; Complex C * ( post-spliceosomal complex ) U2 / U5 / U6 remain bound to the lariat, and the 3 ' site is cleaved and exons are ligated using ATP hydrolysis. The spliced RNA is released, the lariat is released and degraded, and the snRNPs are recycled. This type of splicing is termed canonical splicing or termed the lariat pathway, which accounts for more than 99 % of splicing. By contrast, when the intronic flanking sequences do not follow the GU - AG rule, noncanonical splicing is said to occur ( see `` minor spliceosome '' below ). The minor spliceosome is very similar to the major spliceosome, but instead it splices out rare introns with different splice site sequences. While the minor and major spliceosomes contain the same U5 snRNP, the minor spliceosome has different but functionally analogous snRNPs for U1, U2, U4, and U6, which are respectively called U11, U12, U4atac, and U6atac. Unlike the major spliceosome, it is found outside the nucleus, but very close to the nuclear membrane. Trans - splicing is a form of splicing that joins two exons that are not within the same RNA transcript. Self - splicing Self - splicing occurs for rare introns that form a ribozyme, performing the functions of the spliceosome by RNA alone. There are three kinds of self - splicing introns, Group I, Group II and Group III. Group I and II introns perform splicing similar to the spliceosome without requiring any protein. This similarity suggests that Group I and II introns may be evolutionarily related to the spliceosome. Self - splicing may also be very ancient, and may have existed in an RNA world present before protein. Two transesterifications characterize the mechanism in which group I introns are spliced : 3'OH of a free guanine nucleoside ( or one located in the intron ) or a nucleotide cofactor ( GMP, GDP, GTP ) attacks phosphate at the 5 ' splice site. 3'OH of the 5 ' exon becomes a nucleophile and the second transesterification results in the joining of the two exons. The mechanism in which group II introns are spliced ( two transesterification reaction like group I introns ) is as follows : The 2'OH of a specific adenosine in the intron attacks the 5 ' splice site, thereby forming the lariat The 3'OH of the 5 ' exon triggers the second transesterification at the 3 ' splice site, thereby joining the exons together. TRNA splicing tRNA ( also tRNA - like ) splicing is another rare form of splicing that usually occurs in tRNA. The splicing reaction involves a different biochemistry than the spliceosomal and self - splicing pathways. In the yeast Saccharomyces cerevisiae, a yeast tRNA splicing endonuclease heterotetramer, composed of TSEN54, TSEN2, TSEN34, and TSEN15, cleaves pre-tRNA at two sites in the acceptor loop to form a 5 ' - half tRNA, terminating at a 2 ', 3 ' - cyclic phosphodiester group, and a 3 ' - half tRNA, terminating at a 5 ' - hydroxyl group, along with a discarded intron. Yeast tRNA kinase then phosphorylates the 5 ' - hydroxyl group using adenosine triphosphate. Yeast tRNA cyclic phosphodiesterase cleaves the cyclic phosphodiester group to form a 2 ' - phosphorylated 3 ' end. Yeast tRNA ligase adds an adenosine monophosphate group to the 5 ' end of the 3 ' - half and joins the two halves together. NAD - dependent 2 ' - phosphotransferase then removes the 2 ' - phosphate group. Evolution Splicing occurs in all the kingdoms or domains of life, however, the extent and types of splicing can be very different between the major divisions. Eukaryotes splice many protein - coding messenger RNAs and some non-coding RNAs. Prokaryotes, on the other hand, splice rarely and mostly non-coding RNAs. Another important difference between these two groups of organisms is that prokaryotes completely lack the spliceosomal pathway. Because spliceosomal introns are not conserved in all species, there is debate concerning when spliceosomal splicing evolved. Two models have been proposed : the intron late and intron early models ( see intron evolution ). Splicing diversity Eukaryotes Prokaryotes Spliceosomal + − Self - splicing + + tRNA + + Biochemical mechanism Diagram illustrating the two - step biochemistry of splicing Spliceosomal splicing and self - splicing involve a two - step biochemical process. Both steps involve transesterification reactions that occur between RNA nucleotides. tRNA splicing, however, is an exception and does not occur by transesterification. Spliceosomal and self - splicing transesterification reactions occur via two sequential transesterification reactions. First, the 2'OH of a specific branchpoint nucleotide within the intron, defined during spliceosome assembly, performs a nucleophilic attack on the first nucleotide of the intron at the 5 ' splice site, forming the lariat intermediate. Second, the 3'OH of the released 5 ' exon then performs a nucleophilic attack at the first nucleotide following the last nucleotide of the intron at the 3 ' splice site, thus joining the exons and releasing the intron lariat. Alternative splicing Main article : Alternative splicing In many cases, the splicing process can create a range of unique proteins by varying the exon composition of the same mRNA. This phenomenon is then called alternative splicing. Alternative splicing can occur in many ways. Exons can be extended or skipped, or introns can be retained. It is estimated that 95 % of transcripts from multiexon genes undergo alternative splicing, some instances of which occur in a tissue - specific manner and / or under specific cellular conditions. Development of high throughput mRNA sequencing technology can help quantify the expression levels of alternatively spliced isoforms. Differential expression levels across tissues and cell lineages allowed computational approaches to be developed to predict the functions of these isoforms. Given this complexity, alternative splicing of pre-mRNA transcripts is regulated by a system of trans - acting proteins ( activators and repressors ) that bind to cis - acting sites or `` elements '' ( enhancers and silencers ) on the pre-mRNA transcript itself. These proteins and their respective binding elements promote or reduce the usage of a particular splice site. The binding specificity comes from the sequence and structure of the cis - elements, e.g. in HIV - 1 there are many donor and acceptor splice sites. Among the various splice sites, ssA7, which is 3 ' acceptor site, folds into three stem loop structures, i.e. Intronic splicing silencer ( ISS ), Exonic splicing enhancer ( ESE ), and Exonic splicing silencer ( ESSE3 ). Solution structure of Intronic splicing silencer and its interaction to host protein hnRNPA1 give insight into specific recognition. However, adding to the complexity of alternative splicing, it is noted that the effects of regulatory factors are many times position - dependent. For example, a splicing factor that serves as a splicing activator when bound to an intronic enhancer element may serve as a repressor when bound to its splicing element in the context of an exon, and vice versa. In addition to the position - dependent effects of enhancer and silencer elements, the location of the branchpoint ( i.e., distance upstream of the nearest 3 ' acceptor site ) also affects splicing. The secondary structure of the pre-mRNA transcript also plays a role in regulating splicing, such as by bringing together splicing elements or by masking a sequence that would otherwise serve as a binding element for a splicing factor. Splicing Response to DNA damage DNA damage affects splicing factors by altering their post-translational modification, localization, expression and activity. Furthermore, DNA damage often disrupts splicing by interfering with its coupling to transcription. DNA damage also has an impact on the splicing and alternative splicing of genes intimately associated with DNA repair. For instance, DNA damages modulate the alternative splicing of the DNA repair genes Brca1 and Ercc1. Experimental manipulation of splicing Splicing events can be experimentally altered by binding steric - blocking antisense oligos such as Morpholinos or Peptide nucleic acids to snRNP binding sites, to the branchpoint nucleotide that closes the lariat, or to splice - regulatory element binding sites. Splicing errors and variation It has been suggested that one third of all disease - causing mutations impact on splicing. Common errors include : Mutation of a splice site resulting in loss of function of that site. Results in exposure of a premature stop codon, loss of an exon, or inclusion of an intron. Mutation of a splice site reducing specificity. May result in variation in the splice location, causing insertion or deletion of amino acids, or most likely, a disruption of the reading frame. Displacement of a splice site, leading to inclusion or exclusion of more RNA than expected, resulting in longer or shorter exons. Although many splicing errors are safeguarded by a cellular quality control mechanism termed nonsense - mediated mRNA decay ( NMD ), a number of splicing - related diseases also exist, as suggested above. Allelic differences in mRNA splicing are likely to be a common and important source of phenotypic diversity at the molecular level, in addition to their contribution to genetic disease susceptibility. Indeed, genome - wide studies in humans have identified a range of genes that are subject to allele - specific splicing. Protein splicing Main article : Protein splicing In addition to RNA, proteins can undergo splicing. Although the biomolecular mechanisms are different, the principle is the same : parts of the protein, called inteins instead of introns, are removed. The remaining parts, called exteins instead of exons, are fused together. Protein splicing has been observed in a wide range of organisms, including bacteria, archaea, plants, yeast and humans. See also Wikimedia Commons has media related to Splicing. cDNA post-transcriptional modification mRNA capping polyadenylation Exon Junction Complex SWAP protein domain, a splicing regulator References Jump up ^ Tilgner, Hagen ; Knowles, David G. ; Johnson, Rory ; Davis, Carrie A. ; Chakrabortty, udipto ; Djebali, Sarah ; Curado, João ; Snyder, Michael ; Gingeras, Thomas R. ; Guigó, Roderic ( 2012 ). `` Deep sequencing of subcellular RNA fractions shows splicing to be predominantly co-transcriptional in the human genome but inefficient for lncRNAs ''. Genome Research. 22 ( 9 ) : 1616 -- 25. doi : 10.1101 / gr. 134445.111. PMC 3431479. PMID 22955974. Jump up ^ William Roy, Scott ; Gilbert, Walter ( 2006 ). `` The evolution of spliceosomal introns : Patterns, puzzles and progress ''. Nature Reviews Genetics. 7 ( 3 ) : 211 -- 21. doi : 10.1038 / nrg1807. PMID 16485020. Jump up ^ Clancy, Suzanne ( 2008 ). `` RNA Splicing : Introns, Exons and Spliceosome ''. Nature Education. 1 ( 1 ) : 31. Retrieved 31 March 2011. ^ Jump up to : Black, Douglas L. ( June 2003 ). `` Mechanisms of Alternative Pre-Messenger RNA Splicing ''. Annual Review of Biochemistry. 72 ( 1 ) : 291 -- 336. doi : 10.1146 / annurev. biochem. 72.121801. 161720. PMID 12626338. Jump up ^ `` Molecular Biology of the Cell ''. 2012 Journal Citation Reports. Web of Science ( Science ed. ). Thomson Reuters. 2013. ^ Jump up to : Taggart, Allison J ; Desimone, Alec M ; Shih, Janice S ; Filloux, Madeleine E ; Fairbrother, William G ( 2012 ). `` Large - scale mapping of branchpoints in human pre-mRNA transcripts in vivo ''. Nature Structural & Molecular Biology. 19 ( 7 ) : 719 -- 21. doi : 10.1038 / nsmb. 2327. PMC 3465671. PMID 22705790. Jump up ^ Corvelo, André ; Hallegger, Martina ; Smith, Christopher W.J. ; Eyras, Eduardo ( 2010 ). Meyer, Irmtraud M, ed. `` Genome - Wide Association between Branch Point Properties and Alternative Splicing ''. PLoS Computational Biology. 6 ( 11 ) : e1001016. doi : 10.1371 / journal. pcbi. 1001016. PMC 2991248. PMID 21124863. Jump up ^ Graveley, Brenton R ; Hertel, Klemens J ; Maniatis, Tom ( June 2001 ). `` The role of U2AF35 and U2AF65 in enhancer - dependent splicing ''. RNA. 7 ( 6 ) : 806 -- 818. doi : 10.1017 / s1355838201010317. PMC 1370132. PMID 11421359. Retrieved 17 December 2014. Jump up ^ Matlin, Arianne J. ; Clark, Francis ; Smith, Christopher W.J. ( 2005 ). `` Understanding alternative splicing : Towards a cellular code ''. Nature Reviews Molecular Cell Biology. 6 ( 5 ) : 386 -- 98. doi : 10.1038 / nrm1645. PMID 15956978. Jump up ^ Matera, A. Gregory ; Wang, Zefeng ( 23 January 2014 ). `` A day in the life of the spliceosome ''. Nature Reviews Molecular Cell Biology. 15 ( 2 ) : 108 -- 121. doi : 10.1038 / nrm3742. PMC 4060434. Retrieved 12 December 2014. Jump up ^ Guth, Sabine ; Valcárcel, Juan ( 1 December 2000 ). `` Kinetic role for mammalian SF1 / BBP in spliceosome assembly and function after polypyrimidine tract recognition by U2AF ''. Journal of Biological Chemistry. 275 ( 48 ) : 38059 -- 66. doi : 10.1074 / jbc. M001483200. PMID 10954700. Retrieved 12 December 2014. Jump up ^ Cheng, Zhi ; Menees, Thomas M. ( 8 November 2011 ). `` RNA splicing and debranching viewed through analysis of RNA lariats ''. Molecular Genetics and Genomics. 286 ( 5 -- 6 ) : 395 -- 410. doi : 10.1007 / s00438 - 011 - 0635 - y. Retrieved 12 December 2014. Jump up ^ Ng, Bernard ; Yang, Fan ; Huston, David P. ; Yan, Yan ; Yang, Yu ; Xiong, Zeyu ; Peterson, Leif E. ; Wang, Hong ; Yang, Xiao - Feng ( 2004 ). `` Increased noncanonical splicing of autoantigen transcripts provides the structural basis for expression of untolerized epitopes ''. Journal of Allergy and Clinical Immunology. 114 ( 6 ) : 1463 -- 70. doi : 10.1016 / j. jaci. 2004.09. 006. PMC 3902068. PMID 15577853. Jump up ^ Patel, Abhijit A. ; Steitz, Joan A. ( 2003 ). `` Splicing double : Insights from the second spliceosome ''. Nature Reviews Molecular Cell Biology. 4 ( 12 ) : 960 -- 70. doi : 10.1038 / nrm1259. PMID 14685174. Jump up ^ König, Harald ; Matter, Nathalie ; Bader, Rüdiger ; Thiele, Wilko ; Müller, Ferenc ( 2007 ). `` Splicing Segregation : The Minor Spliceosome Acts outside the Nucleus and Controls Cell Proliferation ''. Cell. 131 ( 4 ) : 718 -- 29. doi : 10.1016 / j. cell. 2007.09. 043. PMID 18022366. Jump up ^ Di Segni, Gianfranco ; Gastaldi, Serena ; Tocchini - Valentini, Glauco P. ( 2008 ). `` Cis - and trans - splicing of mRNAs mediated by tRNA sequences in eukaryotic cells ''. Proceedings of the National Academy of Sciences. 105 ( 19 ) : 6864 -- 9. Bibcode : 2008PNAS... 105.6864 D. doi : 10.1073 / pnas. 0800420105. JSTOR 25461891. PMC 2383978. PMID 18458335. Jump up ^ Trotta, Christopher R ; Miao, Feng ; Arn, Eric A ; Stevens, Scott W ; Ho, Calvin K ; Rauhut, Reinhard ; Abelson, John N ( June 1997 ). `` The Yeast tRNA Splicing Endonuclease : A Tetrameric Enzyme with Two Active Site Subunits Homologous to the Archaeal tRNA Endonucleases ''. Cell. 89 ( 6 ) : 849 -- 858. doi : 10.1016 / S0092 - 8674 ( 00 ) 80270 - 6. Retrieved 17 December 2014. Jump up ^ Westaway, Shawn K ; Phizicky, Eric M ; Abelson, John ( 5 March 1988 ). `` Structure and function of the yeast tRNA ligase gene ''. The Journal of Biological Chemistry. 263 ( 7 ) : 3171 -- 6. PMID 3277966. Retrieved 17 December 2014. Jump up ^ Paushkin, Sergey V ; Patel, Meenal ; Furia, Bansri S ; Peltz, Stuart W ; Trotta, Christopher R ( April 2004 ). `` Identification of a Human Endonuclease Complex Reveals a Link between tRNA Splicing and Pre-mRNA 3 ′ End Formation ''. Cell. 117 ( 3 ) : 311 -- 321. doi : 10.1016 / S0092 - 8674 ( 04 ) 00342 - 3. PMID 15109492. Retrieved 17 December 2014. Jump up ^ Soma, Akiko ( 1 April 2014 ). `` Circularly permuted tRNA genes : their expression and implications for their physiological relevance and development ''. Frontiers in Genetics. 5. doi : 10.3389 / fgene. 2014.00063. Retrieved 17 December 2014. Jump up ^ Abelson, John ; Trotta, Christopher R ; Li, Hong ( 22 May 1998 ). `` tRNA Splicing ''. Journal of Biological Chemistry. 273 ( 21 ) : 12685 -- 12688. doi : 10.1074 / jbc. 273.21. 12685. PMID 9582290. Retrieved 17 December 2014. Jump up ^ Fica, Sebastian M. ; Tuttle, Nicole ; Novak, Thaddeus ; Li, Nan - Sheng ; Lu, Jun ; Koodathingal, Prakash ; Dai, Qing ; Staley, Jonathan P. ; Piccirilli, Joseph A. ( 6 November 2013 ). `` RNA catalyses nuclear pre-mRNA splicing ''. Nature. 503 ( 7475 ) : 229 -- 234. doi : 10.1038 / nature12734. PMC 4666680. PMID 24196718. Retrieved 17 December 2014. Jump up ^ Pan, Qun ; Shai, Ofer ; Lee, Leo J ; Frey, Brendan J ; Blencowe, Benjamin J ( 2008 ). `` Deep surveying of alternative splicing complexity in the human transcriptome by high - throughput sequencing ''. Nature Genetics. 40 ( 12 ) : 1413 -- 5. doi : 10.1038 / ng. 259. PMID 18978789. Jump up ^ Eksi, R ; Li, HD ; Menon, R ; Wen, Y ; Omenn, GS ; Kretzler, M ; Guan, Y ( Nov 2013 ). `` Systematically differentiating functions for alternatively spliced isoforms through integrating RNA - seq data ''. PLOS Computational Biology. 9 ( 11 ) : e1003314. doi : 10.1371 / journal. pcbi. 1003314. PMC 3820534. PMID 24244129. Jump up ^ Li, HD ; Menon, R ; Omenn, GS ; Guan, Y ( Jun 17, 2014 ). `` The emerging era of genomic data integration for analyzing splice isoform function ''. Trends in genetics : TIG. 30 ( 8 ) : 340 -- 347. doi : 10.1016 / j. tig. 2014.05. 005. PMC 4112133. PMID 24951248. Jump up ^ Jain, Niyati ; Morgan, Christopher ; Rife, Brittney ; Salemi, Marco ; Tolbert, Blanton ( 24 November 2015 ). `` Solution Structure of the HIV - 1 Intron Splicing Silencer and its Interactions with the UP1 Domain of hnRNP A1 ''. Journal of Biological Sciences. ^ Jump up to : Lim, Kian Huat ; Ferraris, Luciana ; Filloux, Madeleine E. ; Raphael, Benjamin J. ; Fairbrother, William G. ( 2011 ). `` Using positional distribution to identify splicing elements and predict pre-mRNA processing defects in human genes ''. Proceedings of the National Academy of Sciences. 108 ( 27 ) : 11093 -- 8. doi : 10.1073 / pnas. 1101135108. PMC 3131313. PMID 21685335. Jump up ^ Warf, M. Bryan ; Berglund, J. Andrew ( 2010 ). `` Role of RNA structure in regulating pre-mRNA splicing ''. Trends in Biochemical Sciences. 35 ( 3 ) : 169 -- 78. doi : 10.1016 / j. tibs. 2009.10. 004. PMC 2834840. PMID 19959365. Jump up ^ Reid, D.C. ; Chang, B.L. ; Gunderson, S.I. ; Alpert, L. ; Thompson, W.A. ; Fairbrother, W.G. ( 2009 ). `` Next - generation SELEX identifies sequence and structural determinants of splicing factor binding in human pre-mRNA sequence ''. RNA. 15 ( 12 ) : 2385 -- 97. doi : 10.1261 / rna. 1821809. PMC 2779669. PMID 19861426. ^ Jump up to : Shkreta L, Chabot B ( 2015 ). `` The RNA Splicing Response to DNA Damage ''. Biomolecules. 5 ( 4 ) : 2935 -- 77. doi : 10.3390 / biom5042935. PMC 4693264. PMID 26529031. Jump up ^ Draper, Bruce W. ; Morcos, Paul A. ; Kimmel, Charles B. ( 2001 ). `` Inhibition of zebrafishfgf8 pre-mRNA splicing with morpholino oligos : A quantifiable method for gene knockdown ''. Genesis. 30 ( 3 ) : 154 -- 6. doi : 10.1002 / gene. 1053. PMID 11477696. Jump up ^ Sazani, Peter ; Kang, Shin - Hong ; Maier, Martin A. ; Wei, Changfu ; Dillman, Jennifer ; Summerton, James ; Manoharan, Muthiah ; Kole, Ryszard ( 2001 ). `` Nuclear antisense effects of neutral, anionic and cationic oligonucleotide analogs ''. Nucleic Acids Research. 29 ( 19 ) : 3965 -- 74. doi : 10.1093 / nar / 29.19. 3965. PMC 60237. PMID 11574678. Jump up ^ Morcos, Paul A. ( 2007 ). `` Achieving targeted and quantifiable alteration of mRNA splicing with Morpholino oligos ''. Biochemical and Biophysical Research Communications. 358 ( 2 ) : 521 -- 7. doi : 10.1016 / j. bbrc. 2007.04. 172. PMID 17493584. Jump up ^ Bruno, I.G. ; Jin, W ; Cote, GJ ( 2004 ). `` Correction of aberrant FGFR1 alternative RNA splicing through targeting of intronic regulatory elements ''. Human Molecular Genetics. 13 ( 20 ) : 2409 -- 20. doi : 10.1093 / hmg / ddh272. PMID 15333583. Jump up ^ Danckwardt, S. ; Neu - Yilik, G ; Thermann, R ; Frede, U ; Hentze, MW ; Kulozik, AE ( 2002 ). `` Abnormally spliced beta - globin mRNAs : A single point mutation generates transcripts sensitive and insensitive to nonsense - mediated mRNA decay ''. Blood. 99 ( 5 ) : 1811 -- 6. doi : 10.1182 / blood. V99. 5.1811. PMID 11861299. Jump up ^ Ward, Amanda J ; Cooper, Thomas A ( 2009 ). `` The pathobiology of splicing ''. The Journal of Pathology. 220 ( 2 ) : 152 -- 63. doi : 10.1002 / path. 2649. PMC 2855871. PMID 19918805. Jump up ^ Hanada, Ken - Ichi ; Yang, James C. ( 2005 ). `` Novel biochemistry : Post-translational protein splicing and other lessons from the school of antigen processing ''. Journal of Molecular Medicine. 83 ( 6 ) : 420 -- 8. doi : 10.1007 / s00109 - 005 - 0652 - 6. PMID 15759099. External links Virtual Cell Animation Collection : mRNA Splicing RNA Splicing at the US National Library of Medicine Medical Subject Headings ( MeSH ) Gene expression Introduction to genetics Genetic code Central dogma DNA → RNA → Protein Special transfers RNA → RNA RNA → DNA Protein → Protein Transcription Types Bacterial Eukaryotic Key elements Transcription factor RNA polymerase Promoter Post-transcription Precursor mRNA ( pre-mRNA / hnRNA ) 5 ' capping Splicing Polyadenylation Histone acetylation and deacetylation Translation Types Prokaryotic Eukaryotic Key elements Ribosome Transfer RNA ( tRNA ) Ribosome - nascent chain complex ( RNC ) Post-translational modification ( functional groups peptides structural changes ) Regulation Epigenetic imprinting Transcriptional Gene regulatory network cis - regulatory element lac operon Post-transcriptional sequestration ( P - bodies ) alternative splicing microRNA Translational Post-translational reversible irreversible Influential people François Jacob Jacques Monod Post-transcriptional modification Nuclear Precursor mRNA 5 ′ cap formation Polyadenylation CPSF CstF PAP PAB2 CFI CFII Poly ( A ) - binding protein RNA editing Polyuridylation RNA splicing Intron / Exon snRNP Spliceosome minor U1 Alternative splicing pre-mRNA factors PLRG1 PRPF3 PRPF4 PRPF4B PRPF6 PRPF8 PRPF18 PRPF19 PRPF31 PRPF38A PRPF38B PRPF39 PRPF40A PRPF40B Cytosolic 5 ′ cap methylation mRNA decapping DCP1A DCP1B DCP2 DCPS EDC3 EDC4 Retrieved from `` https://en.wikipedia.org/w/index.php?title=RNA_splicing&oldid=824469778 '' Categories : Gene expression Spliceosome RNA splicing Hidden categories : Wikipedia articles that are too technical from December 2016 All articles that are too technical Articles needing expert attention from December 2016 All articles needing expert attention Talk Contents About Wikipedia Aragonés Bosanski Català Čeština Deutsch Eesti Ελληνικά Español Esperanto فارسی Français Galego Italiano עברית ქართული Қазақша Nederlands 日本 語 Norsk Polski Português Română Русский Simple English Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska தமிழ் Türkçe Українська 中文 Edit links This page was last edited on 7 February 2018, at 15 : 16. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: where does pre mrna splicing occur in eukaryotes
Answer: spliceosome