Interaction between GPIb alpha and Fc gamma IIA receptor in human platelets

Glycoprotein (GP) m (alpha and beta) in platelets forms a noncovalent heter o-oligomeric complex with GPIX and GPV and serves as a receptor for von Wil lebrand factor (vWF), which mediates the initial adhesion of platelets to t he subendothelium after vascular damage and also plays a role in thrombin-i nduced platelet activation. We investigated the interaction between GPIb al pha and Fc gamma IIA receptor using a yeast two-hybrid system and mutagenes is, and we identified residues R542G543R544 in GPIb alpha and D298D299D300 in Fc gamma IIA receptor as the primary interaction sites. These results fu rther confirmed the interaction between GPIb alpha and Fc gamma IIA recepto r and support the hypothesis that the signal transduction of GPIb-IX-V that leads to platelet activation may be partially mediated through Fc gamma HA receptor. (C) 1999 Academic Press.