Inositol phospholipid signalling pathway

The Inositol signalling pathway is activated when a signal molecule binds to the receptor of a trimeric G protein.The binding of the signal molecule causes the GDP bound to the G protein to exchanged for GTP, this induces a conformational change and the alpha subunit dissociates itself from the beta and gamma subunits. The alpha subunit then activates phospholipase C. The phospholipase C then cleaves phosphoinositol 4,5- biphosphate (PIP₂); producing Diacylglycerol (DAG) and Inositol 1,4,5 triphosphate (IP₃). DAG remains embedded in the phospholipid membrane, whereas IP₃ moves into the cytoplasm. IP₃ then binds to IP₃ gated Ca²⁺ release channels on the membrane of the endoplasmic reticulum, this in turn releases Ca²⁺ ions, which binds to Protein Kinase C (PKC). The DAG also binds to PKC, which consequently activates the Protein Kinase C. The PKC then phosphorylates various proteins in order to amplify the signal. 

References  Alberts B, Johnson A, Lewis J, Morgan D, Raff M, Roberts K, Walter P. Molecular Biology of THE CELL. 6th edition. New York: Garland Science, Taylor & Francis Group, LLC, an informa bussiness. 2015