Glycome Atlas
protein
Also known as THBD, CD141, BDCA-3
Plain-language answer
Thrombomodulin is a protein that sits on the surface of the cells lining blood vessels, facing into the bloodstream. It grabs onto thrombin, a clotting protein, and changes what thrombin does, switching it from promoting clots to helping shut clotting down.12
By turning thrombin into an anti-clotting signal, thrombomodulin helps keep the vessel surface from clotting when it should not. When the vessel lining is injured, thrombomodulin can be cut loose and appear in the blood, so a rising blood level is treated as a sign that the endothelium is damaged.1
Technical detail
Thrombomodulin (THBD) is a transmembrane endothelial glycoprotein that binds thrombin and serves as a cofactor for thrombin-mediated activation of protein C, a central anticoagulant pathway of the vessel surface, and whose shed soluble form increases with endothelial injury.12
Thrombomodulin is expressed on the luminal endothelial surface, where it binds thrombin and redirects its activity away from fibrin formation toward activation of protein C. Activated protein C then inactivates coagulation cofactors, so thrombomodulin is a key element of the endothelial anticoagulant system that keeps clotting in check on the healthy vessel wall.1
A subset of thrombomodulin molecules is post-translationally modified with a chondroitin sulfate glycosaminoglycan chain, a proteoglycan form whose sulfated chain augments thrombin binding and the protein's anticoagulant cofactor activity.2
Endothelial injury and glycocalyx disruption are accompanied by proteolytic release of thrombomodulin from the cell surface, and elevated soluble thrombomodulin in plasma is used as an index of endothelial damage in inflammatory and vascular disease states.1
Human relevance
Elevated soluble thrombomodulin is associated with endothelial injury and disturbed coagulation in inflammatory and critical illness, where loss of surface thrombomodulin weakens the protein C anticoagulant pathway.1
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References