PathwayStep674 PathwayStep671 PathwayStep686 Activation of conventional Protein Kinase C Disinhibition of SNARE formation Response to elevated platelet cytosolic Ca2+ Activation of phospholipase C enzymes results in the generation of second messengers of the phosphatidylinositol pathway. The events resulting from this pathway are a rise in intracellular calcium and activation of Protein Kinase C (PKC). Phospholipase C cleaves the phosphodiester bond in PIP2 to form 1,2 Diacylglycerol (DAG) and 1,4,5-inositol trisphosphate (IP3). IP3 opens Ca2+ channels in the platelet dense tubular system, raising intracellular Ca2+ levels. DAG is a second messenger that regulates a family of Ser/Thr kinases consisting of PKC isozymes (Nishizuka 1995). DAG achieves activation of PKC isozymes by increasing their affinity for phospholipid. Most PKC enzymes are also calcium-dependent, so their activation is in synergy with the rise in intracellular Ca2+. Platelets contain several PKC isoforms that can be activated by DAG and/or Ca2+ (Chang 1997). Authored: de Bono, B, 2004-08-13 07:29:26 Pubmed8424766 Reactome Database ID Release 4376005 Reactome, http://www.reactome.org ReactomeREACT_1280 Platelet degranulation