Lecture-6-RNA-modifification

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Unformatted text preview: r intron splicing •  5 donor site – typically GU •  3 acceptor site – typically AG •  Branch point sequence. Splicing: How it works Intron Splicing: Lariat is an important intermediate structure http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html How does the splicesome know where to go? http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html EukaryoticGeneRegulation 1.  Controls   Howmuch   When–timeduringdevelopment   Where–tissue/celltype 2.  Levels   RNA   Attranscriptioninitiation–mostcommon   Duringsplicingorprocessing   Post ­‑transcriptionalstability–common ­‑ miRNA ­‑mediated   Protein •  Translationinitiation/elongation •  proteinstability–ubiquitinsystem •  proteinmodification 19 snRNA:SmallNuclearRNAs •  Introns –  Removedduringpre ­‑mRNAmaturationthroughtwotransesterificationreactions.  •  Spliceosome –  Catalyzesintronremovalandsplicingofexons –  ComplexofsnRNAsandsnRNPs(smallnuclearribonucleoproteins) –  5snRNPsU1,U2,U4,U5andU6areinvolvedinthemajorityofthepre ­‑mRNAsplicing. •  Pre ­‑spliceosome –  5′ ­‑endoftheU1snRNAbasepairswiththe5′junction(donorsiteor5′splicesite) –  DisruptionoftheU1snRNA–5 junctionbasepairing… –  AllowsotherspliceosomalcomponentsU4/U5/U6tointeractwiththedonorsite 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Splicinginaction…. Splicinginaction…. 39 40 Splicing defects can cause human disease A Splicing Defect Caused by an Alu Insertion 41 NeuroGibromatosis The Spliceosome A machine made of proteins and snRNAs that splices pre ­mRNA into mRNA snR...
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This document was uploaded on 01/18/2014.

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