| Formulation | 50%glycerol/water(v/v) |
| Storage | -20°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | N/A |
| ShelfLife(properlystored) | 12months |
ThedomainstructureofproteinSisrepresented,where:GLA=regioncontainingγ-carboxyglutamicacidresidues,EGF=regioncontainingsequenceshomologoustohumanepidermalgrowthfactor,TSR=thrombinsensitiveregion,?=regionofunknownfunctionwhichreplacesthecatalytictriadfoundinvitaminK-dependentserineproteases.
SampleGelInformation:
| Load | HumanProteinS,1µgperlane |
|---|---|
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
Overview:
ProteinSisasinglechainvitaminK-dependentproteinwhichisthoughttofunctioninboththecoagulationandcomplementcascades(1,2).Approximately60%ofproteinScirculatinginplasmaiscomplexedtoC4bbindingprotein(C4BP).Ithasbeensuggestedthatg-carboxyglutamicacid(gla)dependentbindingofproteinStonegativelychargedphospholipidsmayfunctiontoconcentrateC4BPatcellsurfacesfollowinginjury.
Inthecoagulationsystem,proteinSfunctionsasananticoagulantcofactorprotein.ActivatedproteinC(APC)formsa1:1stoichiometriccomplexwithproteinSinthepresenceofCa2+andphospholipidvesicles(Kd=6x10-9M)(3).InthepresenceofproteinS,amoderateincrease(3-10fold)intherateoffactorVaandfactorVIIIainactivationbyAPCisobservedinplasmaandonthesurfaceofunstimulatedplatelets.ProteinSboundtoC4BPdoesnotpossessAPCcofactoractivity.Recently,anadditionalbindingproteinwhichenhancestheactivityofproteinShasbeendescribed(4).ProteolyticinactivationofproteinSbythrombinhasbeenproposedasaregulatorymechanisminthissystem.AsinglecleavagebythrombinabolishesproteinScofactoractivitybyremovinganNH2-terminalpeptide(Mr=8000)whichcontainsthegladomain.
ThedomainstructureofproteinSissimilartothatoftheothervitaminK-dependantcoagulationfactorswiththeexceptionthatproteinSdoesnotpossessthecatalytictriad.ProteinSisasinglechainproteincontaining10glaresiduesintheNH2-terminaldomainand4epidermalgrowthfactor(EGF)domains.
HumanproteinSisisolatedfromfreshfrozenplasmabyacombinationofconventionalmethods(9)andimmunoaffinitychromatographyasdescribedbyJennyetal.(5).PurifiedproteinSissuppliedin50%(vol/vol)glycerol/H2Oandshouldbestoredat-20°C.PurityisdeterminedbySDS-PAGEanalysis.
Properties:
| Localization | Plasma,freeandcomplexedtoC4BP | |||||
|---|---|---|---|---|---|---|
| Plasmaconcentration | 10µg/ml(free)(6) | |||||
| Modeofaction | CofactorforactivatedproteinC | |||||
| Molecularweight | 69,000(7) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | 5.0-5.5(7) | |||||
| Structure | singlechain,NH2-terminalgladomain,fourEGFdomains | |||||
| Percentcarbohydrate | 7%(7) | |||||
| Post-translationalmodifications | oneβ-hydroxyaspartate(8)tenglaresidues(7),threeβ-hydroxyasparagine(8) |
