Antithrombin

Function

Antithrombin (AT) inactivates several enzymes of the coagulation cycle. AT is relatively inactive until it binds the heparan sidechains of the microvasculature.
▪ α-AT contains 4 occupied glycosylation sites and is found in blood palsma.
▪ β-AT contains only 3 occupied glycosylation sites.
▪ AT-I refers to the absorption of thrombin to fibrin.
▪ AT-II and heparin interfere with the interaction of thrombin and fibrinogen.
▪ AT-III inactivates thrombin in plasma.
▪ AT-IV becomes activated during blood coagulation.
See details for the antithrombin pentasaccharide complex in Molecular Playground/Antithrombin-Heparin.

Disease

AT deficiency diseases are: Acquired AT deficiency and Inherited AT deficiency. AT deficiency is involved in thrombosis and pulmonary embolism.

Relevance

AT activity is enhanced upon binding to the anticoagulant drug heparin.

Structural highlights

The binding of AT to the heparans or the heparin drug is to a core pentasaccharide. The binding induces conformational change of AT.

3D structures of antithrombin

Updated on 04-November-2015