Chapter 6(1).pptxVIP免费

Chapter6Ribosome，synthesisandtransportofproteinsRibosome:structureandfunctionTransportofproteinsFateofproteinsOUTLINE1.Ribosome(核糖体)•Theribosomeisasmall,campactribonucleoproteinparticle(核糖核蛋白颗粒)composedofRNAsandproteins，andinvolvedinproteinsynthesis.RibosomeforshortProkaryotes1)Ribosomestructure(1)Shapeofribosome--nomembranestructure--twosubunits(2)ChemicalcomponentofribosomesEachsubunitconsistsofrRNAsandproteinsRNAsinsidethesubunit,proteinsoverthesurface(TheproteinsofthesmallsubunitisnamedasS1,S2,…..andtheproteinsofthelargesubunitisnamedasL1,L2,…..).(31)Maintypesofribosomes3.9×103-4.5×103kDacomponentProkaryotes(70S)Eukaryotes(80S)componentratiotwo-thirdsrRNA(2/3)one-thirdprotein(1/3)three-fifthsrRNA(3/5)two-fifthsrprotein(2/5)rRNAs?◆16SrRNA：1457-1544nt，theconservedsequenceofACCUCCUUAatthe3end′iscomplementarywiththepurine-richSDsequence.◆18SrRNA:thehomologousnucleotidesequenceto16SrRNAatthe3′end.SequencecharacteristicsofrRNAs◆5SrRNA(细菌)：120or116nt,twohighlyconservedsequences,oneCGAACsequencemayrecognisetRNA,theothermayinteractwithGTψCGsequenceofTΨCloop.◆5.8SrRNA：160nt，theCGAACsequencesimilartohighlyconservedoneof5SrRNA.◆23SrRNA：2904nt,thesequencecomplementarywithtRNAfMetsequence.◆28SrRNA：3890-4700nt，unknownfunction.TψC臂负责和核糖体上的rRNA识别结合CompositionsofribosomefromdifferentsourcesSourceRibosomeSubunitsribosomalRNAsCytoplasm80S60S(大亚基)28S(Eukaryote)40S(小亚基)18S,5.8S,5SCytoplasm70S50S(大亚基)23S(Prokaryote)30S(小亚基)16S,5SMitochondrion55-60S45S(大亚基)16S(Mamalian)35S(小亚基)12SMitochondrion75S53S(大亚基)21S(Yeast)35S(小亚基)14SMitochondrion78S60S(大亚基)26S(Plant)45S(小亚基)18S,5SChloroplast70S50S(大亚基)23S30S(小亚基)16S,5S2)BiogenesisofRibosome◆SynthesisofribosomalproteinsandrRNAs◆Assemblyofsubunits(1)SynthesisandprocessingofrRNAsEukaryoticcells:rRNAgenesof18S,5.8Sand28SrRNA,asatranscriptionunit,aretandemly(串联地)repeated100–1,000timesonchromosomes.◆Transcription●RNApolymeraseI●primarytransc...