Glycoprotein IIb/IIIa

Definition

Glycoprotein IIb/IIIa, also known as the platelet integrin receptor, is a crucial component in the process of blood clotting and coagulation. It is a membrane-bound protein complex found on the surface of platelets that plays a central role in platelet aggregation and thrombus formation.

5 Must Know Facts For Your Next Test

1. The glycoprotein IIb/IIIa complex is the most abundant integrin on the surface of platelets, with approximately 80,000 copies per platelet.
2. Activation of the glycoprotein IIb/IIIa complex leads to a conformational change that increases its affinity for fibrinogen, von Willebrand factor, and other adhesive proteins, promoting platelet aggregation.
3. Inhibition of the glycoprotein IIb/IIIa complex is a common therapeutic target for antiplatelet drugs, as it can help prevent or treat thrombotic events.
4. The glycoprotein IIb/IIIa complex is involved in the final common pathway of platelet aggregation, where it serves as a receptor for fibrinogen and von Willebrand factor.
5. Genetic defects or autoimmune disorders that affect the glycoprotein IIb/IIIa complex can lead to bleeding disorders, such as Glanzmann's thrombasthenia.

Review Questions

• Describe the role of the glycoprotein IIb/IIIa complex in platelet aggregation and thrombus formation.
  • The glycoprotein IIb/IIIa complex is a crucial mediator of platelet aggregation, the process by which platelets adhere to one another to form a plug at the site of a blood vessel injury. Upon platelet activation, the glycoprotein IIb/IIIa complex undergoes a conformational change that increases its affinity for adhesive proteins, such as fibrinogen and von Willebrand factor. This allows the platelets to bind to each other and to the damaged endothelium, leading to the formation of a thrombus, or blood clot, which helps to stop bleeding and promote wound healing.
• Explain how the inhibition of the glycoprotein IIb/IIIa complex can be used as a therapeutic target for antiplatelet drugs.
  • The glycoprotein IIb/IIIa complex is a common target for antiplatelet drugs because it plays a central role in the final common pathway of platelet aggregation. By inhibiting the binding of adhesive proteins, such as fibrinogen, to the glycoprotein IIb/IIIa complex, these drugs can prevent or disrupt the formation of blood clots, reducing the risk of thrombotic events like heart attacks and strokes. Antiplatelet drugs that target the glycoprotein IIb/IIIa complex are widely used in the management of acute coronary syndromes, percutaneous coronary interventions, and other conditions where the prevention of unwanted clot formation is crucial.
• Discuss the clinical implications of genetic defects or autoimmune disorders that affect the glycoprotein IIb/IIIa complex.
  • Genetic defects or autoimmune disorders that disrupt the function of the glycoprotein IIb/IIIa complex can lead to bleeding disorders, such as Glanzmann's thrombasthenia. In this condition, the inability of platelets to aggregate properly due to a deficiency or dysfunction of the glycoprotein IIb/IIIa complex results in impaired hemostasis and an increased risk of bleeding episodes. Patients with Glanzmann's thrombasthenia may experience prolonged bleeding after minor injuries, nosebleeds, and excessive bleeding during surgical procedures. Understanding the critical role of the glycoprotein IIb/IIIa complex in platelet function is essential for the diagnosis, management, and treatment of these rare, but clinically significant, bleeding disorders.

Related terms

Platelet Aggregation: The process by which platelets adhere to one another, forming a plug at the site of a blood vessel injury to stop bleeding.

Thrombus: A blood clot that forms within a blood vessel, potentially obstructing blood flow.

Integrin: A family of cell surface receptors that mediate cell-cell and cell-extracellular matrix adhesion, including the glycoprotein IIb/IIIa complex.