Fig. 6
Production of PA and DGPP by different pathways and interconversion reactions mediated by phosphorylation and dephosphorylation. Green denotes phosphorylation reactions, and red denotes dephosphorylation reactions. Other colors indicate key enzymes in these pathways. In the phosphorylation pathway: PI3K or PI4K, phosphatidylinositol 3-kinase or 4-kinase, respectively; PI4P5K, phosphatidylinositol 4-phosphate 5-kinase; PI3P5K, phosphatidylinositol 3-phosphate 5-kinase; ITPK, inositol-tetrakisphosphate 1-kinase; IPK5, inositol-pentakisphosphate 2-kinase and DGK, diacylglycerol kinase. In the dephosphorylation pathway: PAP, phosphatidic acid phosphatase; 5PTase, inositol polyphosphate 5-phosphatase; PI3P phosphatidylinositol 3-phosphatase and PI5P, phosphatidylinositol 5-phosphatase. Key enzymes: PLD, phospholipase D; NPC, nonspecific phospholipase C; PI-PLC, phosphatidylinositol-specific phospholipase C and PLA, phospholipase A. PI, phosphatidylinositol; PIP, phosphatidylinositol phosphate; PIP2, phosphatidylinositol bisphosphate; PIP3, phosphatidylinositol trisphosphate; DAG, diacylglycerol; PA, phosphatidic acid; DGPP, diacylglycerol pyrophosphate; IPx, inositol polyphosphates; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PG, phosphatidylglycerol and PS, phosphatidylserine