Once platelets are activated, granules secrete clotting mediators, including both ADP and TXA2. These then bind their respective receptors on platelet surfaces, in both an autocrine and paracrine fashion (binds both itself and other platelets). The binding of these receptors result in a cascade of events resulting in an increase in intracellular calcium (e.g. via Gq receptor activation leading to Ca2+ release from platelet endoplasmic reticulum Ca2+ stores, which may activate PKC). Hence, this calcium increase triggers the calcium-dependent association of gpIIb and gpIIIa to form the activated membrane receptor complex gpIIb/IIIa, which is capable of binding fibrinogen (factor I), resulting in many platelets "sticking together" as they may connect to the same strands of fibrinogen, resulting in a clot. The coagulation cascade then follows to stabilize the clot, as thrombin (factor IIa) converts the soluble fibrinogen into insoluble fibrin strands. These strands are then cross-linked by factor XIII to form a stabilized blood clot.
↑ 1.01.1Vickers JD (July 1999). "Binding of polymerizing fibrin to integrin alpha(IIb)beta(3) on chymotrypsin-treated rabbit platelets decreases phosphatidylinositol 4,5-bisphosphate and increases cytoskeletal actin". Platelets. 10 (4): 228–37. doi:10.1080/09537109976077. PMID16801097.
↑Calvete JJ (April 1995). "On the structure and function of platelet integrin alpha IIb beta 3, the fibrinogen receptor". Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine. 208 (4): 346–60. doi:10.3181/00379727-208-43863a. PMID7535429.
↑Shattil SJ (August 1999). "Signaling through platelet integrin alpha IIb beta 3: inside-out, outside-in, and sideways". Thrombosis and Haemostasis. 82 (2): 318–25. PMID10605720.