| Formulation | 20mMTris,150mMNaCl,pH7.4 |
| Storage | -80°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | N/A |
| ShelfLife(properlystored) | 12months |
Thedomainstructureofhumanosteonectinisillustrated,where:CHO=potentialglycosylationsites,OP=potentialserinephophorylationsites,EF-Hand=regionshomologoustocalciumbindingdomainsincalmodulin,andacidic=NH2-terminalacidicdomain.
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | Humanosteonectin,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
Overview:
Osteonectinisanacidic,noncollagenousglycoprotein(Mr=29,000)originallyisolatedfromfetalandadultbovinebonematrix(1-5).InvitrobovineboneosteonectinbindstypeIcollagen,calcium(Kd=3x10-7M)andhydroxyapatite(Kd=8x10-8M)andhasbeenshowntobeapotentinhibitorofhydroxyapatiteseededcrystalgrowth(6).Inthiscontextithasbeensuggestedthatosteonectinmayplayanimportantroleintheregulationofbonemetabolismbybindinghydroxyapatitetocollagen.Recently,proteinshomologoustoosteonectinhavebeenidentifiedinanumberofcelltypes,mostofwhichareassociatedwithextracellularmatrixproduction(7).Theaminoacidsequence(fromCDNAsequences)ofoneoftheseproteins,humanplacentalSPARCisidenticaltohumanboneosteonectin.
Osteonectinhasalsobeenidentifiedasanalphagranulecomponentofhumanplateletsandissecretedduringactivation.Asmallportionofthesecretedosteonectinisexpressedontheplateletcellsurfaceinanactivationdependentmanner(8).Purifiedplateletosteonectinisasinglechainmoleculewhichexhibitsaslightlylargerapparentmolecularweightthanthatofosteonectinderivedfrombone(8).TheNH2-terminalsequencesofplateletandbone-derivedosteonectinareidentical,butthetwoproteinsdifferwithregardtotheextentotglycosylation(8-10).
HumanplateletosteonectinisisolatedfromthrombinactivatedplateletsasdescribedbyKelm,etal.(8).BovineboneosteonectinisisolatedfromdemineralizedbonebythemethodofRombergetal.(2).Bothproteinsaresuppliedin0.02MTris,0.15MNaCl,pH7.4,andshouldbestoredat-80oC.PurityisjudgedbySDS-PAGEanalysis.
Properties:
| Localization | Bone,platelets,plasma(0.9ug/ml)*(5),serum(2.6ug/ml)**(5). | |||||
|---|---|---|---|---|---|---|
| Modeofaction | Unknown | |||||
| Molecularweight | 32,700(humanbone,fromcDNA)(1) 29,000(bovinebone,bysedimentationequilibrium)(3) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | 5.5***(3) | |||||
| Structure | Singlechain,NH2terminalacidicdomain,cysteinerichserpinhomologydomain,2EFhanddomains. | |||||
| Post-translationalmodifications | Phosphoserine(11) | |||||
| Notes | *DeterminedforHumanPlasma **DeterminedforHumanSerum ***DeterminedforBovineBone |
