细胞膜和细胞表面.pptVIP

去垢剂detergent去垢剂是一端亲水、另一端疏水的两性小分子,是分离与研究膜蛋白的常用试剂。01离子型去垢剂(SDS)和非离子型去垢剂（TritonX-100）02SDS:CH3-(CH2)11-OSO3-Na+03与蛋白在人工脂质体上的表现不同，在活细胞里，蛋白的移动速率要低的多1/10-30。However,thediffusionrateofaproteinintheplasmamembraneofintactcellsisgenerally10–30timeslowerthanthatofthesameproteinembeddedinsyntheticsphericalbilayerstructures(liposomes).Thesefindingssuggestthatthemobilityofintegralproteinsintheplasmamembraneoflivingcellsisrestrictedbyinteractionswiththerigidsubmembranecytoskeleton.生物膜一些概念单位膜01.流动镶嵌模型01.细胞连接

Cell–CellandCell–MatrixAdhesion,INTEGRATINGCELLSINTOTISSUES细胞通过细胞粘连分子相互连接Cellsintissuescanadheredirectlytooneanother(cell–celladhesion)throughspecializedintegralmembraneproteinscalledcell-adhesionmolecules(CAMs)thatoftenclusterintospecializedcelljunctions0102细胞黏连分子分成钙黏素，免疫球蛋白超家族，整合素，选择素。其他参加细胞粘连的膜蛋白AlargenumberofCAMsfallintofourmajorfamilies:thecadherins,immunoglobulin(Ig)superfamily,integrins,andselectins.Someothermembraneproteins,whosestructuresdonotbelongtoanyofthemajorclassesofCAMs,alsoparticipateincell–celladhesioninvarioustissues.相同粘连分子的连接称为同亲性homophilicbinding，不同粘连分子连接称为异亲性heterophilicbinding细胞粘连可以是牢固的，如上皮细胞间的连接；也可以是微弱的，短暂的，如免疫细胞穿越血管内皮。Cell–celladhesionscanbetightandlonglastingorrelativelyweakandtransient.Theassociationsbetweennervecellsinthespinalcordorthemetaboliccellsintheliverexhibittightadhesion.Incontrast,immune-systemcellsinthebloodcanexhibitonlyweak,short-lastinginteractions,allowingthemtorollalongandpassthroughabloodvesselwallontheirwaytofightaninfectionwithinatissue.细胞粘连分子先形成二聚体或寡聚体，这种作用是细胞内的，然后在不同细胞间粘连分子相互连接，这种作用是细胞间的，后者能促进细胞内的聚合。First,CAMsononecellassociatelaterallythroughtheirextracellulardomainsorcytosolicdomainsorbothintohomodimersorhigher-orderoligomersintheplaneofthecell’splasmamembrane;thesein