PathwayStep678 PathwayStep679 PathwayStep676 PathwayStep677 PathwayStep675 PathwayStep680 PathwayStep681 PathwayStep682 PathwayStep683 PathwayStep684 PathwayStep685 Release of platelet cytosolic components Surface deployment of platelet alpha granule membrane components Release of (inferred) platelet cytosolic components Release of platelet secretory granule components Release of Calumenin Release of 78 kDa glucose-regulated protein Exocytosis of Proactivator polypeptide Exocytosis of platelet dense granule content ABCC4 accumulation of dense granule contents Exocytosis of platelet alpha granule contents Surface deployment of platelet dense granule membrane components Platelet degranulation GENE ONTOLOGYGO:0002576 Platelets function as exocytotic cells, secreting a plethora of effector molecules at sites of vascular injury. Platelets contain a number of distinguishable storage granules including alpha granules, dense granules and lysosomes. On activation platelets release a variety of proteins, largely from storage granules but also as the result of apparent cell lysis. These act in an autocrine or paracrine fashion to modulate cell signaling. <br><br><br> Alpha granules contain mainly polypeptides such as fibrinogen, von Willebrand factor, growth factors and protease inhibitors that that supplement thrombin generation at the site of injury. Dense granules contain small molecules, particularly adenosine diphosphate (ADP), adenosine triphosphate (ATP), serotonin and calcium, all recruit platelets to the site of injury. Pubmed14630798 Reactome Database ID Release 43114608 Reactome, http://www.reactome.org ReactomeREACT_318