Diacylglycerol

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Diacylglycerol

Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Diacylglycerol (DAG) is a second messenger signaling lipid 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.

Shown at right is 1-palmitoyl-2-oleoyl-glycerol but DAG can have many different combinations of fatty acids attached at the SN-1 and SN-2 positions.

[edit] Functions

Diacylglycerol has a number of functions in the cell:

as a source for prostaglandins
stimulation of protein kinase C
as a precursor of the endocannabinoid 2-arachidonoylglycerol

[edit] Synthesis

Diacylglycerol is a pre-cursor to triacylglycerols (triglycerides). Synthesis begins with glycerol-3-phosphate, which is a product of glycolysis (usually in cytoplasm of liver or adipose tissue). Two fatty acid molecules are added to yield phosphatidic acid. Phosphatidic acid is then de-phosphorylated to form diacylglycerol.

Note: Diacylglycerol may form a triacylglycerol with the addition of a third fatty acid molecule.