Fig. 8. Proposed mechanism of InsP-supported fibrinogen-platelet-crosslinking.
(A) InsP6 is present in the cytosol and enriched in α-granules. (B) Thrombin, ADP and collagen I stimulation of platelets activates PLC, resulting in generation of InsP3 from PIP2. InsP3 is step-wise phosphorylated to InsP6 by inositol phosphate kinases, IP3K, IPMK and IP5K and is at least partially transported into α-granules. Fibrinogen in complex with InsP6 is released from platelets and exposed on the plasma membrane where it could recruit plasma fibrinogen. (C) InsP6 bound to fibrinogen promotes crosslinking of activated platelets and fibrinogen, thereby stabilizing the growing thrombus.