Activated platelets rapidly release the contents of three distinct types of preformed intracellular vesicles. Dense granules contain phosphates, purines, and bioactive amines. Lysosomes contain glycosidases and acid proteases. Proteins from alpha granule membranes localize to the platelet surface upon granule release and contribute to platelet adhesion and activation. Alpha granules contain a large number of soluble mediators that promote inflammation, both positively and negatively regulate the coagulation cascade, and promote wound healing to help resolve tissue damage.
Please view our related interactive pathways covering additional aspects of platelet activation:
| Dense Granules | ||
|---|---|---|
| ADP | Magnesium | |
| ATP | Polyphosphates | |
| Calcium | Pyrophosphate | |
| Epinephrine | Serotonin | |
| Histamine | STIM1, 2 (NovusBio.com) | |
| Alpha Granule Membrane Proteins | ||
|---|---|---|
| CD9 | Glut3 | SNAP23 |
| CD31/PECAM-1 | Glycoprotein V/CD42d | Syntaxin 4, 8, 11 (NovusBio.com) |
| CD36/SR-B3 | GPVI | Syntaxin-BP2/Munc18-2 |
| CD40 Ligand/TNFSF5 | GPIX/CD42a (NovusBio.com) | Syntaxin-BP3/Munc18c |
| GP1BB (NovusBio.com) | Integrin alpha 2b beta 3 | TREML1/TLT-1 |
| CD63 | Integrin alpha 6/CD49f | UNC13D/Munc13-4 |
| CD109 | P-Selectin/CD62P | VAMP-2, 3, 7, 8 (NovusBio.com) |
| Epimorphin/Syntaxin 2 | PKHD1L1/Fibrocystin-L (NovusBio.com) | |
| ESAM | Septin-5/CDCrel-1 (NovusBio.com) | |
| Fc gamma RIIA/CD32a | Siglec-7/CD328 | |
Upon activation, platelets rapidly release the contents of three distinct types of preformed intracellular vesicles. Dense granules contain phosphates, purines, and bioactive amines. Lysosomes contain glycosidases and acid proteases. Proteins from alpha granule membranes localize to the platelet surface upon granule release and contribute to platelet adhesion and activation. Alpha granules also contain a large number of soluble mediators that promote inflammation, both positively and negatively regulate the coagulation cascade, and promote wound healing to help resolve tissue damage.