glycerolbackbone

The glycerol backbone refers to the glycerol moiety that serves as the core scaffold for glycerolipids, including triglycerides and glycerophospholipids. It is built from three carbon atoms arranged in a triol structure and provides attachment points for fatty acids and, in many lipids, a polar head group.

In triglycerides, three fatty acid molecules are esterified to the hydroxyl groups of the glycerol backbone, one on each of the three carbons. In glycerophospholipids, two fatty acids are typically attached at the first and second carbons, and a phosphate-containing head group is attached at the third carbon. The nature and arrangement of the fatty acids and head group on the glycerol backbone determine the physical properties and biological roles of the lipid.

Biosynthesis of the glycerol backbone-containing lipids begins with glycerol-3-phosphate, a central intermediate. Glycerol can be phosphorylated to glycerol-3-phosphate by glycerol kinase. Fatty acyl chains are then added by acyltransferases to produce phosphatidic acid, a key precursor. Phospholipid synthesis proceeds from phosphatidic acid by removal of the phosphate to form diacylglycerol, which can be further acylated to triglycerides or converted into various phospholipids by attachment of different head groups.

Function and significance: the glycerol backbone is the foundational scaffold that supports diverse lipid species, influencing membrane structure, curvature, and signaling. Glycerol-based lipids are major components of cellular membranes (as phospholipids and glycolipids) and fat storage molecules (as triglycerides). The backbone concept is widely used in lipidomics to describe the common structural framework shared by many glycerolipids.