| Formulation | Lyophilizedfrom20mMHepes,150mMNaCl,pH7.4 |
| Storage | 4°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | N/A |
| ShelfLife(properlystored) | 12months |
Thedomainstructureofthefibronectinmonomerisrepresented.NativefibronectiniscomposedoftwosubunitswhicharelinkedthroughtwointerchaindisulfidebondsneartheCOOH-terminalofeachsubunit.Thetransglutaminase(factorXIIIa)crosslinkingsiteisindicatedbythearrow.Variousmacromolecularbindingdomains,includingheparin(HEP),fibrin(FBN),andcollagenareshown.Thecelladhesionsite(CELL)whichpossessesanRGDSsequenceisdepicted.
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | Load:HumanFibronectin,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;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:
| Localization | plasma,0.3mg/ml(1) extracellularmatrix(2) | |||||
|---|---|---|---|---|---|---|
| Modeofaction | mediatescellattachmenttoextracellularmatrix(9-11) | |||||
| Molecularweight | 550,000(3) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | ~5.0(19) | |||||
| Structure | heterodimer(3) | |||||
| Percentcarbohydrate | 4-10%,dependingonsource(12) |
