Glycoprotein iib/iiia

Composite glycoprotein from the integrin family. The glycoprotein IIb/IIIa, also known as "fibrinogen receptor", can be detected on the surface of activated platelets. The glycoprotein IIb/IIIa is a receptor for von Willebrand factor (vWF) as well as for fibrinogen. It promotes the aggregation of thrombocytes.

When the thrombocytes are activated, a conformational change of the GPIIb/IIIa receptors occurs. This is triggered by the binding of the von Willebrand receptor to the glycoprotein Ib/IX/V. As a result, thrombocytes can now bind soluble fibrinogen. This enables bridging between the thrombocytes, which ultimately leads to thrombus formation.

Substances that specifically block these fibrinogen receptors on the platelet surface are called GP-IIb/IIIa receptor antagonists (also glycoprotein 2b/3a inhibitors or GP-IIb/IIIa inhibitors). They act by blocking the GP-IIb/IIIa receptors on the surface of the thrombocytes and thus inhibit the formation of blood clots. These include abciximab, eptifibatide, tirofiban which lead to platelet function inhibition.

A mutation of the glycoprotein IIb/IIIa gene is the cause of Glanzmann thrombasthenia.