Caping and Splicing

r B '5'CappingP.PaPLdremardPi2,2,7(TriphosphateB&nimethylIrCappingcap - 01,02.44.05GTPGuonglyl transferase(2activities)enzymeGMP + PPibifunctionalU6. rmellylenzymeV4BP chap5G-(PP.P& B d7th N of G melhylatedinSAM-methy group dobar5'-5'SAHininurvalCH3-Capbond.CopoGPPPX. B &subsequent methylation CH3 10 capcap'Cap recogCH32'OH ofriboseCapaG-P-P-PLcitaCH3CH3-Cap2-by CBC 20/80G-P-P-Ptoandprotectedcap helps to recroenormal exonudeasesibosome to s'end andcap2cannotcleave capprotectedpromote translationend Shelp in transport, NuclearParecomplex recognize thiscap3functionsMTHF T HFNH3+NH3+CH-COOCH-COOSAHSAM+ ATP(H2),(CH2)2IS-AdenoinSCH3CH3methionine + ATPSAM+ PiPP;methyl donarSAM-CH3S-adenosyl Homocysteine (SAH)Methyl tehahydroplate ortion3'}5'exonsplice splice sositemRNAEukaryofic boRNA, exonsis exoninterveined with introo, removal of intron1-- intronby eplicingGroupstranshriteexctselfairsGrop IIG-ollbrunchIntron removed Dear3' by splicingGroup III - spliciousesiteinternalmediated pressA-OH5'GU3'APpyAGstartstopBranchsitePolypyrimidine sitehighlyconserved - Adenine 2'OH -participate in catalysisGroup IIadenylicacidsplicejunctionnears'endGUAtransesterificationppyAGPG20Hattacktoattack- transesterification5'3'G OHAPpyAGPGwereJesterbondeleavelarietanderstheformP5+Aevolutionalcyloplasmexonucleasebronch site, self splicingdegrade ExptitIsolapeDNAanDenatureallowtointosinglebind/pairstarIntron cannot baveonly few portionssites to bindin mRNA.of DNA can bird/split genepair with the mRNAconceptavelasexonsand severalsegionsthat2000pploopout from mRNA,avg lengthof intron 3,500bpsloops correspont tosometimes reach 500,000bps.MRIVAmore mutationsin introns herC. .elegans20,000 genes - simple organismthey have moreno:of nucleotidesH. sapeliss25,000 genes - complexorgonism.Intron allow to generate alternative splicing,and protein diversityI [2.1 13+ [47singlegene122312343424Groteincombinationeg:- DscamDown Syndrom cell Adhesion Molecule geneDSCAMneuronal guidence in D.melanagastersinglegene (38,016 - alternative splicing protein combinationneurondevelopmentProtein for asonal guidance are coded from this gene Group. 1 splicing- Most ancient- Branch site absent- external goonglic (G-otleguarylic acid )acid residuce in the attacking group- Release lipear intronsplice JunchP-GOH3' splice junctionattackG-OH guany lic5'3'acidOH P-P-2GMP.attack3linear intronGroups 3 -Splicing mediate by spliciosomes (SnRP, snurps)Spliciosome mediated splicing.ribozymesmost evolved.large subunit 235-> peptide bondformationU7bistone mRNA splicing, > H3 &H4RNASC P 5'endi of ERNAU3RN splicinghighly conserved and don' bave (otronU1 1,2,4,5,67RNARNP,+catalytic RNA (ribozyme)Severalincrease RNA ;MRNAproteins efficiency [materase protein]5356U2 AFplyJ2mask catalytic activity of1SF15A2U2Fsplicing Factor I4,U5 U6of bes intiallyrecruiteinapropriatelypoothU2 associate factioncatalyse3 U15'branchsite splicesiterecruitesplicing (transesterification4U2branch siteinteract to 3' splice site mutation rate more for intergenic sequer), muculus "Ohighless selection pressure intran can diverge and develop alternativesplicing mechanismepliciorome mediated only few regions are necesary to beconserved self splicing group IIspliciosome arsi sted group-IIIIfU1 detach. properly positionU4 detach &U6catalysesmallcrainsplicinInteractic1laugedomain3AFInteractor 35(Early) E comples5'"AU1 binds to 5 splice3'spliceEsite, SF2 to branchsic &splicU2U2AFt ppy bindingU2AftoSFI,F PPy& 3 spliceAcomplex siterecruteRNA pairing.SF1 removed3'and recruiteUsUIHAPPyU2A5U2complex(4U2AF requiterecruiteU2 higheltstrimes to 3'SF1leavesinrecent4RNA pairingsplice site displace04/055O6complex U2AusAppynow theyBU2catalyticinteract togethercomplexUsdisplace U1loopingU4+U2 displaceO- ppyU6catalysetransesterificationloopingreactiondisplace U1 U1 by 05trima interactingwith 54046splic sitemore affinity&2 pair and 6&4pypaining3catalysisofdemarkedGEremovedadjock53'0HaltackU4e6pappyleaves