Table 1.
Main Constituents of Platelet Secretory Granules
| Dense Granules | |
| Solutes | 5HT, ADP, ATP, GDP, GTP, Ca, Mg, PyroPi, histamine |
| Membrane | CD62P, CD63, GP's Ib & IIb/IIIa, LAMP2, Src, Ral-1 |
| Alpha Granules | |
| Adhesive glycoproteins | fibronectin, vitronectin, vWF, TSP |
| Proteoglycans | PF4, ßTG, serglycin, HRGP & ßTG Ag's: PBT, CTAP-III, NAP-2 |
| Mitogens: | PDGF, TGFß, ECGF, EGF, VEGF, VPE, IGF, IL-ß |
| Protease inhib's | TFPI, PAI-1, PDCI, α2-antiplasmin, C1 inhibitor, α2-antitrypsin, α2-macroglobulin |
| Coagulation: | Factors V, XI, XIII, HMWK, fibrinogen, PAI-1, protein C, protein S, protein C inhibitor, TSP-1, TSP-2 |
| Membrane* | CD9, CD31, CD36, CD62P, CD144, GLUT-3, |
| * Not including several GP's found also on plasma membrane | |
| Misc. | IgG, IgM, IgA, albumin, GP Ia/multimerin, osteonectin, clusterin, angiostatin, endostatin, plasminogen |
| Lysosomal Granules (Lysosomes) | |
| Acid proteases | cathepsins D & E, carboxypeptidases A & B, collagenase, acid phosphatase, aryl sulfatase |
| Glycohydrolases | heparinase, b-galactosidase, b-glucuronidase, b-N-acetyl-glucosaminodase, b-glycerophosphatse, b-D-glucosidase, a-D-glucosidase, a-L-fucosidase, b-D-fucosidase, a-L-arabinosidase, a-D-mannosidase |
| Membrane | LIMP-1, LAMP-1, -2 |
| Dense Tubules | Principal Ca store for internal secretion |
Contents of the three main granules (dense, alpha, lysosomal) and the "dense tubules" are listed in Table 1.