Which receptor acts as the receptor for fibrinogen?

Which receptor acts as the receptor for fibrinogen?

• A. GPIb/IX
• B. GPIIb/IIIa
• C. GPIa/IIa
• D. GPIc/IIa

Answer: (B)

The key receptor for fibrinogen on activated platelets is the GPIIb/IIIa complex (integrin αIIbβ3). When platelets are activated, GPIIb/IIIa shifts to a high-affinity state and binds fibrinogen from the plasma. Fibrinogen has two binding sites, so it can link two platelets together through their GPIIb/IIIa receptors, forming the platelet–platelet bridges that drive aggregation and the formation of a platelet plug. This specific interaction is a central step in primary hemostasis and is why GPIIb/IIIa inhibitors effectively prevent platelet aggregation in therapeutic settings. In contrast, GPIb/IX mainly binds von Willebrand factor to mediate initial platelet adhesion under high shear, not fibrinogen bridging. GPIa/IIa is a collagen receptor that helps platelets stick to exposed subendothelial collagen, while GPIc/IIa is not a recognized receptor for fibrinogen in this pathway.

The key receptor for fibrinogen on activated platelets is the GPIIb/IIIa complex (integrin αIIbβ3). When platelets are activated, GPIIb/IIIa shifts to a high-affinity state and binds fibrinogen from the plasma. Fibrinogen has two binding sites, so it can link two platelets together through their GPIIb/IIIa receptors, forming the platelet–platelet bridges that drive aggregation and the formation of a platelet plug. This specific interaction is a central step in primary hemostasis and is why GPIIb/IIIa inhibitors effectively prevent platelet aggregation in therapeutic settings.

In contrast, GPIb/IX mainly binds von Willebrand factor to mediate initial platelet adhesion under high shear, not fibrinogen bridging. GPIa/IIa is a collagen receptor that helps platelets stick to exposed subendothelial collagen, while GPIc/IIa is not a recognized receptor for fibrinogen in this pathway.