Thrombomodulin, Rabbit (CD141, TM, Fetomodulin

Thrombomodulin (TM) is an integral membrane glycoprotein expressed on the surface of endothelial cells. Its discovery by Esmon and Owen has focused attention on the importance of the protein C anticoagulant pathway (1,2). TM serves as a cofactor for protein C activation by forming a 1:1 stoichiometric complex with thrombin (Kd=10e-10M), which accelerates the rate of protein C activation by 1000-fold relative to the rate with thrombin alone. In addition to facilitating protein C activation, the binding of thrombin to TM drastically alters the procoagulant activity of thrombin. When bound to TM, thrombin no longer clots fibrinogen, activates factor V, inactivates protein S or triggers platelet aggregation. \n\nTM is a single chain protein composed of 5 distinct domains. The domain structure of TM is similar to the low density lipoprotein (LDL) receptor. A short cytoplasmic domain containing a free cysteine is located at the COOH-terminal end and is joined by a membrane spanning region to an O-glycosylation rich domain. The latter is followed by an epidermal growth factor (EGF) homology region and the NH2-terminal hydrophobic domain. The EGF homology region contains 6 EGF-like domains and contains the binding sites for both thrombin and protein C.\n\nLocalization: \nEndothelial cell membrane, traces of degraded, yet functional, TM detected in human urine and plasma (7,8)\n\nMode of Action: \nCofactor; enhances the proteolytic activation of protein C by thrombin\n\nSpecific activity: \n~500 U/mg\n\nExtinction Coefficient: E1%1cm, 280nm=8.8 (5)\n\nIsoelectric Point: 2.5 (2)\n\nStructure: \nSingle chain, NH2-terminal hydrophobic domain, six EGF domains, one O-glycosylation rich domain, one transmembrane domain, COOH-terminal cytoplasmic domain\n\nPost-translational Modifications: b-hydroxyasparagine (0.5 mol/mol of protein) (6)\n\nStorage and Stability:\nAliquot to avoid repeated freezing and thawing and freeze at -70 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Aliquots are stable for at least 6 months.

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SPECIFICATIONS

Catalog Number

T5048

Size

50ug

Form

Supplied as a liquid in 0.02M Tris, 0.15M sodium chloride, pH 7.4, 0.05% polidocanol (PDOC).

Purity

(same/more than)95% by SDS-PAGE. Thrombomodulin is isolated from rabbit lung by a modification (3) of the procedure described by Galvin et al. (4). Purity is determined by SDS-PAGE analysis and activity is determined using a chromogenic assay for protein C activation.

References

1. Esmon, C.T., et al., Proc. Natl. Acad. Sci. USA, 78: 2249 (1981). 2. Esmon, N.L., Semin. Thromb. Hemostas., 13: 454 (1987). 3. Haley, P.E., et al., J. Biol. Chem., 264: 16303 (1989). 4. Galvin, J.B., et al., J. Biol. Chem., 262,:2199 (1987). 5. Esmon, N.L., et al., J. Biol. Chem., 257, 859 (1982). 6. Stenflo, J., et al., J. Biol. Chem., 263, 21 (1988). 7. DeBault, L.E., et al., Lab Invest., 54, 172 (1986). 8. Ishi, J., et al., J. Clin. Invest., 76: 2178 (1985).