In a patient with von Willebrand disease, platelet adhesion at sites of vascular injury is impaired. Von Willebrand factor mediates platelet adhesion under high shear stress by bridging exposed subendothelial collagen to which platelet receptor?

• A GPIIb/IIIa (integrin αIIbβ3)
• B GPIa/IIa (integrin α2β1)
• C GPVI collagen receptor
• D GPIb/IX/V complex ✓

Explanation

vWF binds exposed subendothelial collagen via its A3 domain and simultaneously binds the platelet GPIb/IX/V complex via its A1 domain, mediating the initial tethering and adhesion of platelets under high shear stress. GPIIb/IIIa (option A) mediates platelet aggregation by binding fibrinogen, not the initial adhesion to collagen via vWF. GPVI and GPIa/IIa are direct collagen receptors but are not the primary vWF-dependent adhesion pathway.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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