Fibrinogen

3D Model

Fibrinogen is shaped like the femur and is a long protein, about 50nm, which is crucial to how it crosslinks platelets to promote blood clotting. The ends of fibrinogen bind to an integrin receptor on one platelet and reach across to bind an integrin on a different platelet forming a bridge between them. Inhibiting this binding reduces the likelihood of clotting. This has been targeted therapeutically using different types of drug: abciximab is a monoclonal antibody, eptifibatide is a peptide inhibitor and tirofiban is a small molecule antagonist. Each has the same end result of inhibiting the binding of fibrinogen. The latter two were derived form snake venoms and these are a promising source of novel antiplatelet drugs.