| Formulation | 25mMHepes,150mMNaCl,pH7.4 |
| Storage | -80°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | N/A |
| ShelfLife(properlystored) | 12months |
Thedomainstructureoftheβ-thromboglobulinmonomerisrepresented.Theβ-thromboglobulinmonomerisan8,800molecularweightpeptidewhichisderivedviaNH2-terminalproteolysisofaprecursormoleculeLAPF-4(lowaffinityplateletfactor-4).AlthoughtheCOOH-terminaldomainofβ-thromboglobulinischaracterizedbyaclusteringofbasiclysineresidues,theaffinityofb-thromboglobulinforheparinissignificantlyweakerthanthatofplateletfactor-4.Initsnativestate,β-thromboglobulinisahomotetramerconsistingoffour,identical,noncovalently-
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | Load:HumanBetaThromboglobulin,1µgperlane |
| Buffer | MES |
| Standard | SeeBluePlus2;Myosin(188kDa),PhosphorylaseB(98kDa),BSA(62kDa),GlutamicDehydrogenase(49kDa),AlcoholDehydrogenase(38kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(17kDa),Lysozyme(14kDa),Aprotinin(6kDa),Insulin,Bchain(3kDa). |
Overview:
β-thromboglobulin(b-TG),isalowmolecularweight,heparin-binding,platelet-derivedprotein(1).Itissimilartoplateletfactor-4(PF-4)inthatitislocalizedwithintheplateletalpha-granuleatlevelsreportedtorangefrom8.1-24.2µgper109platelets(2,3).Therelativeconcentrationofβ-TGinplateletsexceedsthatofplasmaby260,000-fold(4)makingβ-TGaconvenientMarkerofplateletactivation.Structurally,β-TGisanalogoustoPF-4inthat,initsnativestate,β-TGisatetramer(1)consistingoffouridentical8800molecularweightpeptidechains(5).IncontrasttoPF-4,β-TGexhibitsaloweraffinityforheparinandalsoexistsasalargermolecularweightspeciesknownas"lowaffinityPF-4"(LAPF-4)(2).β-TGisderivedfromtheproteolyticremovaloffourNH2-terminalaminoacidresiduesfromaLAPF-4(6,7).Immunologicalscreeningofpartiallyfractionatedsupernatantfromactivatedplateletsrevealedahighlybasicformofβ-TGdistinctfromLAPF-4(7).Thisbasicβ-TGspecies,termedplateletbasicprotein(PBP),wassubsequentlyisolated(8)andlaterconcludedfromimmunological,peptidesequencing,andproteolyticprocessingstudiestobeahighermolecularweightprecursorformofbothLAPF-4andβ-TG(9,10).
Thephysiologicalfunctionofβ-TGisnotknown.Whileearlystudiessuggestedthattheprecursorformsofβ-TGweremitogenicformousefibroblasts(8,11),itwaslaterconcludedthatthisactivitywasduetogrowthfactorcontamination(10).β-TGhasalsobeenreportedtoinhibitprostacyclin-I2productionbyendothelialcells(12),however,therelevanceofthiseffecthasbeencalledintoquestion(13,14).Thechemotacticactivityofplateletalpha-granuleproteinsforhumanfibroblastshasbeenattributedtobothPF-4andβ-TG(15).
Humanβ-TGispreparedfromthesupernatantofactivatedplateletsbyheparin-agaroseaffinitychromatographyandgelfiltration(1,2).Thepurifiedproteinissuppliedin25mMHepes,150mMNaClpH7.4andshouldbestoredat-80°C.PurityisassessedbySDS-PAGEanalysis.
Properties:
| Localization | plateletalpha-granule(3) | |||||
|---|---|---|---|---|---|---|
| PlasmaConcentration | 100-200µg/ml | |||||
| Modeofaction | heparin-bindingprotein:Plasmaconcentrationusedasamarkerofplateletactivation | |||||
| Molecularweight | 35,800(1) | |||||
| Extinctioncoefficient |
| |||||
| Structure | homotetramer(monomer,Mr~8800)(5) |
