FormulationLyophilizedfrom20mMHepes,150mMNaCl,pH7.4Storage4°CPurity>95%bySDS-PAGEActivityDeterminationN/AShelfLife(properlystored)12monthsDomainStructureofFibronectinThedomainstructureofthefibronectinmonomerisrepresented.NativefibronectiniscomposedoftwosubunitswhicharelinkedthroughtwointerchaindisulfidebondsneartheCOOH-terminalofeachsubunit.Thetransglutaminase(factorXIIIa)crosslinkingsiteisindicatedbythearrow.Variousmacromolecularbindingdomains,includingheparin(HEP),fibrin(FBN),andcollagenareshown.Thecelladhesionsite(CELL)whichpossessesanRGDSsequenceisdepicted.SampleGelInformation:GelNovex4-12%Bis-TrisLoadLoad:HumanFibronectin,1µgperlaneBufferMOPSStandardSeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa)Overview:Fibronectin(cold-insolubleglobulin)isahighmolecularweight,adhesive,glycoproteinfoundinbothplasma(1)andtheextracellularmatrix(2).Fibronectiniscomposedoftwopeptidechainsofapproximately275,000molecularweightwhicharelinkedthroughtwointerchaindisulfidebondsattheCOOH-terminalendofthemolecule(3).Thestructureoffibronectinischaracterizedbythreedifferenttypesofrepeatinghomologoussequenceunits(4,5).The45aminoacidtype-IrepeatconstitutestheNH2-andCOOH-terminalendsoftheprotein.Thetwo60aminoacidtype-IIsegmentsfollowthefirstninetype-IrepeatsattheNH2-terminus.The90aminoacidtype-IIIsegmentsoccupythecentralregionofthefibronectinmolecule.Structuraldifferencesbetweenplasmaandcellularfibronectin(6,7)aswellasbetweenthetwosubunitsofplasmafibronectin(8,9)havebeenidentified.ThesedifferenceslikelyoriginateduetotranscriptionalandposttranscriptionaleventsinvolvingmRNAsplicing(10).Theapparentfunctionoffibronectinistomediatecellattachmentbyinteractingwithcellsurfacereceptorsandextracellularmatrixcomponents(10-12).FibronectincontainsanArg-Gly-Asp-Ser(RGDS)cellattachment-promotingsequencewithinoneofthetype-IIIhomologysegmentsinthemiddleofthemolecule(13).ThisRGDSsiteisrecognizedbyspecificRGDS-dependentcellreceptors(13)whicharemembersoftheintegrinfamilyofproteins(14).Fibronectinbindingtoactivatedplatelets(15)ismediatedthroughtheRGDScelladhesionsequence(16).Otherbindingdomainsspecificforsuchextracellularmacromoleculesasheparin,fibrin(ogen),andcollagen(10-12)havebeenidentifiedandmaybeimportantinthefibronectin-mediatedadhesionofplateletstotheextracellularmatrixofendothelialcells(17).Fibrin-fibronectincomplexesarestABIlizedbythefactorXIIIa-catalyzedcovalentcross-linkingoffibronectintotheachainoffibrin(18).Fibronectinisisolatedfromhumanplasmabythermalprecipitation,ionexchange,andgelatin-agaroseaffinitychromatography.Thepurifiedproteinissuppliedasalyophilizate.PurityisassessedbySDS-PAGEanalysis.Properties:Localizationplasma,0.3mg/ml(1)extracellularmatrix(2)Modeofactionmediatescellattachmenttoextracellularmatrix(9-11)Molecularweight550,000(3)ExtinctioncoefficientE1%1cm,280nm=14.0Isoelectricpoint~5.0(19)Structureheterodimer(3)Percentcarbohydrate4-10%,dependingonsource(12)