Product Description

Rabbit Thrombomodulin

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=10-10M), 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.

TM 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 s for both thrombin and protein C.

Thrombomodulin is isolated from rabbit lung by a modification (3) of the procedure described by Galvin et al. (4) and is supplied as an aqueous solution in 0.02 M Tris, 0.15 M NaCl, pH 7.4, containing 0.05 % polidocanol, and can be stored at -80 C for up to a year. Purity is determined by SDS-PAGE analysis and activity is determined using a chromogenic assay for protein C activation.