Diacylglycerol (DAG) is a second messenger molecule made by phospholipase C (PLC) (a membrane-bound enzyme), together with inositol triphosphate (IP3). Although inositol triphosphate (IP3) diffuses into the cytosol, diacylglycerol (DAG) stays close to the plasma membrane, due to its hydrophobic properties. IP3 stimulates the release of calcium ions from the smooth endoplasmic reticulum while DAG is still membrane associated and activates protein kinase C (PKC). However, for DAG to activate PKC, there needs to be a cytosolic increase in calcium ions which is one of the functions of IP3.

Diacylglycerol has two major functions in the cell:

• as a source for prostaglandins
• stimulation of protein kinase C

Signal transduction

Diacylglycerol