ABSTRACT
This chapter summarizes the pathways of biosynthesis of phospholipids and triacylglycerol in mammalian tissues. Essentially, these pathways have been known for over 25 years. The relative importance of each pathway might differ from cell to cell, and, additionally, different molecular species of phospholipids might use different pathways in the same cell. Some of the major phospholipids can be synthesized by modification of the polar headgroup of a preexisting lipid. The major phospholipids can be synthesized by modification of the polar headgroup of a preexisting lipid. Thus, phosphatidylethanolamine can be converted into phosphatidylcholine by three successive N-methylations of the amino group, phosphatidylserine can be converted into phosphatidylethanolamine by decarboxylation, and phosphatidylinositol can be converted into phospha tidylinositol-4,5-bisphosphate by phosphorylation of the inositol ring. Phosphatide acid plays a key role in the metabolism of glycerolipids, since it is the precursor of both phospholipids and neutral glycerides.
