In: Biology
Correct. Phospholipase C (PLC) cleaves the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) into diacyl glycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). PLC is activated by many G protein activators. PIP2 also acts as the substrate for synthesis of the rare lipid phosphatidylinositol 3,4,5-trisphosphate (PIP3), which is used for signaling in many reactions.
DAG and IP3, are important second messengers that control diverse cellular processes and are substrates for synthesis of other important signaling molecules. When PIP2 is cleaved, DAG bounds to the membrane, and IP3 is released as a soluble structure into the cytosol. IP3 diffuses through the cytosol to bind to the IP3 receptors, particularly calcium channels in the smooth endoplasmic reticulum (ER). This causes the cytosolic concentration of calcium to increase, causing a cascade of intracellular changes and activity.In addition, calcium and DAG together work to activate protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity.
Both DAG and IP3 are substrates for the synthesis of regulatory molecules. DAG is the substrate for the synthesis of phosphatidic acid, a regulatory molecule. IP3 is the rate-limiting substrate for the synthesis of inositol polyphosphates, which stimulate multiple protein kinases, transcription, and mRNA processing. Regulation of PLC is important in maintaining cellular physiology.