Chapter 24: Acylglycerol & Sphingolipid Metabolism

Acylglycerol & Sphingolipid Metabolism emphasizes that triacylglycerols, the predominant lipids in adipose tissue, are synthesized through the progressive acylation of glycerol-3-phosphate, a process closely linked to carbohydrate metabolism via glycolytic intermediates. A critical metabolic junction occurs at phosphatidate, where the pathway diverges to produce either storage fats or functional phosphoglycerols such as phosphatidylcholine and cardiolipin. The discussion extends to specialized ether lipids, including plasmalogens and platelet-activating factor, which originate from dihydroxyacetone phosphate within peroxisomes. Furthermore, the text details the catalytic roles of various phospholipases in remodeling membrane lipids and generating signaling molecules. A significant portion of the chapter is dedicated to sphingolipids, all of which derive from the central precursor ceramide. These molecules are vital for cell recognition, adhesion, and acting as receptors for bacterial toxins. The clinical relevance of these metabolic processes is underscored through explorations of lung surfactant deficiency in neonatal respiratory distress syndrome, the demyelination processes seen in multiple sclerosis, and various sphingolipidoses—inherited lysosomal storage disorders like Gaucher and Tay-Sachs diseases—which result from specific enzymatic defects in the lipid catabolism pathway.