How are phospholipids synthesized in cells?

The process of phospholipid synthesis in primary cells occurs mainly in the ER and Golgi apparatus. The synthesis of phospholipids begins with the formation of glycerol-3-phosphate (Gro-3-P). Glycerol-3-phosphate is first synthesized from dihydroxyacetone phosphate via the enzyme glycerol-3-phosphate dehydrogenase and through its reduction by NADH. Gro-3-P is then acylated through glycerophosphate acyltransferase (GPAT) to produce lysophosphatidic acid. The next step is acylation of the lysophosphatidic acid (which requires an acyl-Coa enzyme). This enzyme acylates the sn-p1 position via an unsaturated or saturated fatty acid. Lysophosphatidic acid is acylated in the ER by the enzyme lysophosphatidic acid acyltransferase to produce phosphatidic acid. The next step is the phosphorylation of the phosphatidic acid. Phosphatidic acid is hydrolyzed to form 1,2,-diacyl-sn-glycerol (DAG) via phosphatidic acid phosphatase. The next step is the addition of different head groups, which results in various different types of phospholipids being formed. As examples, the addition of phosphate produces phosphatidic acid, the addition of serine forms phosphatidylserine, and the addition of choline makes phosphatidylcholines. The majority of phosphoric acid is produced de novo through the Kennedy pathway, with DAG as the precursor. The Kennedy pathway synthesizes PtdCho and PtdEtn from choline and ethanolamine. These newly synthesized phospholipids are then transported to the lipid bilayer. On a side note, peroxisomes play a vital role in the synthesis of specialized phospholipids required for nerve cell myelination.