Fig. 2.
Storage and secretion of InsP6 by platelets. (A) Thrombin-stimulated platelets were washed to detach surface bound InsP6. The platelet supernatant and the wash was analyzed by MDD-HPLC. InsP6 (standard shown left) was detected only in the wash fraction (cell surface, right). (B) Platelets were fractioned by histodenz gradient and enrichment of dense granules in the pellet (DG) was analyzed by Western blotting using an antibody against the dense granule marker ABCC4. (C) InsPs were extracted from from whole platelets (middle) as well as the dense granule containing pellet (right) with TCA and analyzed by MDD-HPLC. InsP standard is shown left. (D and E) Platelets were fractioned by a sucrose gradient and after differential centrifugation the pellets were analyzed for the α-granule containing fractions by VWF ELISA (D) and InsPs were analyzed by MDD-HPLC (E).