Phospholipid Synthesis in Mammalian Cells

Phospholipids are composed of a hydrophobic diacylglycerol (DAG) moiety attached to a hydrophilic phospho- head group. Amphipathic phospholipids are components of membranes, secreted in protein-lipid complexes and precursors for signalling factors. Phospholipid biosynthesis occurs primarily in the endoplasmic reticulum or where the endoplasmic reticulum contacts other organelles for efficient coupling of synthesis and transport. De novo phospholipid biosynthesis utilises DAG or CDP-DAG to which are added choline, ethanolamine, inositol and glycerol to form phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and cardiolipin, respectively. The phospholipid head groups are further modified by serine base change, methylation and phosphorylation. Similarly, phospholipid fatty acids are remodelled by exchange reactions. This combination of biosynthetic and remodelling pathways generates diverse phospholipid species that are essential for cellular function.