1. Catabolisms of triacylglycerols and phospholipids.1

2. Synthesis of Triacylglycerols (TGs) and Glycerophospholipids (GPLs)
Glycerol 3-phosphate can be obtained either by the reduction of dihydroxyecetone phosphate (primarily) or by the phosphorylation of glycerol (to a lesser extent). 2

3. Formation of phosphatidate
Two separate acyl transferases (AT) catalyze the acylation of glycerol 3-phosphate.
The first AT (esterification at C1) has preference for saturated fatty acids; the second AT (esterification at C2) prefers unsaturated fatty acids. 3

4. Phosphatidic acid (phosphatidate) is an common intermediate in the synthesis of TGs and GPLs
Phosphatidate can be converted to two precursors: diacylglycerol (precursor for TGs and neutral phospholipids) - cytidine diphosphodiacylglycerol (CDP-diacylglycerol) (precursor for acidic phospholipids) 4

5. Phospha- tidyl- etha-nolamine
Synthesis of TGs and neutral phospholipids
Phospha tidyl etha-nolamine
Triacyl-glycerol
Phosphatidylcholine 5

6. Synthesis of TGs
Diacylglycerol can be acylated to triacylglycerol (in adipose tissue and liver)
Enzyme: acyltransferase 6

7. Synthesis of neutral phospholipids
CDP-choline or CDP-ethanolamine are formed from CTP by the reaction:
CTP + choline phosphate  CDP-choline + PPi
CTP + ethanolamine phosphate  CDP-ethanolamine + PPi
Diacylglycerol react with CDP-choline or CDP-ethanolamine to form phosphatidylcholine or phosphatidylethanolamine 7

8. 8

9. Synthesis of acidic phospholipids9

10. Phosphatidylinositol can be converted to phosphatidylinositol 4,5-biphosphate which is the precursor of the second messenger inositol 1,4,5-triphosphate 10

11. Interconver-sions of phosphati-dylethanol-amine and phospha-tidylserine11