课件-细胞生物学fchapter5.endomembrane system or intracellular compartment-20172sf

1●Foldingandassemblyofnascent(初生的)polypeptides

Bip

(heavy-chain

Bindingprotein):aHsp70-likechaperoneprotein

bindstotheunfoldedpolypeptidechainandmediatesproteinfoldingandtheassemblyofmultisubunitproteinswithintheER2---内质网上合成的不能正确折叠的无效蛋白被内质网膜上一种Sec61复合物转运体（Sec61translocator

）运出内质网腔,进入细胞质溶质，随后胞质中N-聚糖酶将该蛋白中连在天冬酰胺上的寡糖链切除，最后通过泛素化降解折叠好的蛋白就可以通过小泡运出。3Glycogenposition(糖原分解)葡萄糖磷酸变位酶糖原颗粒附着于SER的胞质面◆FunctionsofSER4

Synthesisandtranslocationofphospholipids(磷脂)磷脂酸Synthesis胞嘧啶核苷二磷酸（CDP）脂肪酰基CoA卵磷脂----Theenzymesforlipid

synthesislieintheSER

membrane,theiractivitysites

facetothecytosol；substratesfromthecytosol，phospholipidtranslocators(磷脂转位子)orflippases(转位酶)transferthephospholipidsintoERlumen.

卵磷脂CoA转移酶3-磷酸甘油乙酰转移酶酰基转移酶磷脂酸磷酸酶二酰基甘油磷酸胆碱转移酶转位酶Detoxification（解毒）:oxygenases(cytochromeP-450：含血红素蛋白的氧化酶)Ca2+storage（钙库）：

Ca2+-ATPases

inthesarcoplasmicreticulummembrane（胞质

10-7mol/LCa2+，内质网腔10-2mol/LCa2+

）Synthesisofsteroidhormones(类固醇激素:生殖腺内分泌细胞和肾上腺皮质）

7●

Exportof

proteinsandlipids82)Golgicomplex(GC)orGolgiapparatus◆1898-CamilloGolgi(Italian）

硝酸银染色发现猫头鹰和猫的神经细胞中靠近核的位置有一种巨大的黑色网状结构--内网器（internalreticularapparatus）--高尔基体（Golgibody）(1)Structure

◆Shape--4-8flattenedmembranevesiclesorsacs(cisternea)surroundedbyanumberofdifferentsizesofsphericalmembranevesicles.光镜：网状结构9◆

StructureofGCmedialcisternae(中间潴泡)

bow-shapedtowardthenucleustowardplasmamembrane10从顺面至反面的几个功能明显的功能域：顺面高尔基网络（Cis-GolgiNetwork：CGN，也称为高尔基内侧网络)

，顺面潴泡（Ciscisternae），中间潴泡（medialcisternae），反面潴泡（Transcisternae），反面高尔基网络（TransGolgiNetwork：TGN

也称为高尔基外侧网络）11FunctionofCGN:GC

entrance,itsmembrane

similartothatofER.

acceptance,identificationandclassificationofsubstancesnewlysynthesizedfromtheERanddispatchesthemtoGCmedialcisternae.Functionofmedialcisternae：glycosylmodificationandtheformationofglycolipidsandpolysaccharidesFunctionofTGN:GCexit–晚期蛋白的修饰（如半乳糖(a)2,6唾液酸化、蛋白质酪氨酸残基的硫酸化及蛋白原的水解加工），proteinsorting,packagingandexportingN乙酰葡糖胺CGN：O--连接糖基化，跨膜蛋白酰基化；日冕病毒的装配TGN低pH，CMP酶阳性“瓣膜”作用，保证单向转运12GCisapolarorganelle(Polarity)：

--GCstructure(Cisregion，medialregionandtransregion)--biochemicalproperities--directionofsubstancetransportation

CGN膜厚6nm近似内质网膜，TGN膜厚10nm近质膜。13

(2)Thenumberandchemicalcomposition

◆Number:moreGCsinsecretorycells.

◆Chemicalcomposition

---proteins(60%)andlipids(40%)主要成分是胆固醇、磷脂和糖脂●

markerenzyme:glycosyltransferase（糖基转移酶）14(3)FunctionsofGCProteinmodificationandprocessing:O-linkedGlycosylation（O-连接的糖基化）ProteinsortingCellsecretionFormationofplantcellwall

Proteoglycan(蛋白聚糖)assemblyparticipatinginlysosomeformationMembranetransformationandrenewing15●proteinmodificationandprocessing

◆O-linkedglycosylation:TheglycosylistransferredtotheOHgroupofser(Throrhyp羟赖氨酸)residueofpolypeptidechain—O-linkedglycosylation.ThefirstglycosylisN-acetylgalactosamine(N-乙酰半乳糖胺),andthenoneafteranothermonosacchavideisadded.连到N原子上，N-连接型连接的寡糖糖残基较多，有分枝发生在内质网膜内O-连接型连接的糖基较少，只有1-4个糖残基，如胶原和血型糖蛋白N—乙酰葡萄糖胺N—乙酰半乳糖胺蛋白质糖基化类型特征

N-连接

O-连接1.合成部位粗面内质网粗面内质网或高尔基体2.合成方式来自同一个寡糖前体一个个单糖加上去3.与之结合的氨基酸残基天冬酰胺丝氨酸、苏氨酸、羟赖氨酸、羟脯氨酸4最终长度至少5个糖残基一般1～4个糖残基，但ABO血型抗原较长5.第一个糖残基

N—乙酰葡萄糖胺N—乙酰半乳糖胺等N-连接与O-连接的寡糖比较17◆ModificationsofN-linkedoligosaccharidesinGolgi成熟的糖蛋白N-乙酰葡萄糖胺半乳糖岩藻糖

唾液酸18寡糖链中最近端的5个糖基（2个GlcNAc和3个Man）称为核心区，在随后的修饰过程中始终保留，其余部分为末端区，进行修饰时要发生改变。19◆Thebiologicalfunctionsofglycosylation（糖基化）①Protectproteinsfromenzymedigestion

andincreaseproteinstability②endowtheproteinswithsignalingfunctionincell-celladhesion（粘附）

；③helpproteinstofoldProperly④markthedifferentproteinswithdifferentlabelstohelpthemtosort.20(胰岛素)◆

Proprotein(蛋白原)

processinginGolgi：inactive

proproteinactivepolypeptide如血清蛋白、胰高血糖素、神经肽前胰岛素原胰岛素原21●

ProteinSortingandExport◆ERretentionproteins◆lysosomeproteins

andmembraneproteins◆

Secretoryproteinsandextracellularmatrix

component--Sortingand

Exporting

mainlydependontheinteractionbetween

sorting

signal（orsignalpatch）ofproteinssortedandsortingreceptors.22▲

ERproteinretentioninER(内质网腔中的可溶性驻留蛋白)●ERretentionsignalattheirC-terminus:

KDEL:Lys-Asp-Glu-Leu-COO-(e.g.Bipprotein)●KDELsignal

receptor:--receptor(GCmembrane):recognizethevesiclescontainingresidentproteinsandreturningtherunawayproteins(沿微管进行）--receptor(ERmembrane):receivetherunawayproteins23Cellsecretion(细胞分泌):----包括蛋白质、糖和脂质的合成、分泌物质的浓缩、加工和成熟，最后通过膜运动排出细胞外。----Organellesinvolvedincellsecretion:ER,GC●

Cellsecretion(细胞分泌)24SecretorypathwaysER→ERlumen→CGN→Medialcisternae→TGN→plasmamembranedischarge(Exocytosis(胞吐作用))proteinsynthesisBuddingprocessingSortingandbuddingfusionwithplasmamembranedischarge加工、修饰和浓缩252023/1/2425◆Constitutivesecretion（恒定性分泌):vesiclescontinuouslyformandcarryproteinsfromtheGolgitothecellsurface（如肝细胞分泌糖蛋白和浆细胞分泌抗体）.◆Regulatedsecretion:hormones,mucus(黏液)ordigestiveenzymesarestoredinsecretoryvesiclesuntilanextracellularsignalstimulatestheirsecretion.

263）lysosome(溶酶体)(1)MorphologicStructure◆Lysosomes:heterogenous

vesicle-like

organellesenclosedbyasinglelayerofmembrane

containmanytypesofdigestiveenzymes.◆animalcells,diameterof0.25～0.8μminvariesinsize,shapeandelectrondensity

小鼠脾脏巨噬细胞中的溶酶体用电镜细胞化学技术显示其中含有的酸性磷酸酶，M：线粒体，L：溶酶体（朴英杰）deDuveetal(比利时1955)—Electronmicroscope-自噬体1974年获得诺贝尔奖27核酸酶蛋白酶糖苷酶酯酶磷酸酶硫酸酶磷脂酶(2)Chemicalcomposition

◆approximately50differentacidhydrolasesinthelysosomelumen,theiroptimalactivityatanacidpH4.6◆markerenzyme:

acidphosphatase(酸性磷酸酶)◆

theprotonpumpsinthelysosomemembranetheprotonpumpinthemembraneacidicinternalenvironment28Factorsof

lysosome

membranestability◆containsprotonpumps(H+-ATPase)tomaintainthehighinternalproton◆containsmanytypesoftransportproteins:exporthydrolyticproductsofthedigestionofmacromoleculestothecytosol◆containshighlyglycosylatedmembraneproteins:toformaprotectivelayerpreventingthemembraneproteinitselfbeingdegradated◆containshighlevelofcholesterol29(3)ClassificationoflysosomesendosomesPhagocytosis异体吞噬Autophagy自体吞噬初级溶酶体初级溶酶体次级溶酶体次级溶酶体30◆Primarylysosome(初级溶酶体：刚从TGN形成的小囊泡，多成球形，内容物均一):novisiblegranuleormembrane

fragments;acidichydrolasesshortof

activity。◆Secondarylysosome(次级溶酶体):acidichydrolasesandsubstrates（granuleormembrane

fragments).形态不规则，体积大，具有异质性▲autophagiclysosome(自噬溶酶体)：当细胞处于紧急状态如饥饿时正常细胞器也会被消化，以产生营养供细胞急需。▲heterophagiclysosome(异噬溶酶体)：细胞通过内吞作用形成吞噬泡和胞饮泡，与初级溶酶体融合后变成异噬溶酶体（吞噬溶酶体或多泡小体）◆residualbodyorpostlysosome(残余小体或后溶酶体)：肝细胞脂褐质◆residualbodyorpostlysosome(残余小体或后溶酶体)：noenzymeactivitybutindigestedresidue,suchasagepigment(epidermiccells)andlipofuscin-脂褐质(livercells).32◆Secondarylysosome(次级溶酶体):▲heterophagiclysosome(异噬溶酶体)

-吞噬溶酶体，▲autophagiclysosome(自噬溶酶体)Phagocytosis（吞噬作用）Autophagy（自体吞噬）Heterophagy（异体吞噬）phagosome（吞噬体）33Autophagy

(自体吞噬-自噬现象）2016年的诺贝尔生理学或医学奖，颁发给了日本科学家大隅良典(Yoshinori

Ohsumi)，以奖励他在阐明细胞自噬（Autophagy，或称自体吞噬）的生物学机制。autophagiclysosome34◆Endocytosis(胞吞作用)isaprocessbywhicheukaryoticcellstakeupextracellularlargemolecules

orgranularmatters.----Pinocytosis(胞饮作用):occurscontinuouslyinalmostallcells35--Phagocytosis(吞噬作用),anactin-mediatedprocessinwhichcellsenvelopbacteriaandotherlargeparticlesinmacrophage(巨噬细胞)andneutrophils(中性粒细胞).macrophageneutrophilsheterophagyphagosome（吞噬体）36Endocytosis(胞吞作用)Endocytosis(胞吐作用)3737Receptor-mediatedendocytosis(胞吞作用)◆LDL(low-densitylipoproteins-低密度脂蛋白),transferrin(转铁蛋白：aniron-bindingproteins),hormones(insulin)andglycoproteinsLDL:

phospholipidandproteins--Cholesterolisfromfoodorsynthsizedintheliver.--TransportedinLDL--LDLreceptorissynthesizedwhenrequired,andincorportedinplasmamembrane.LDL(球形脂蛋白)核心800个磷脂分子500个辅基蛋白B-100BindingtoLDLreceptor38TheLDLreceptor-mediatedendocytosisLowPHintheendosom