AAT Bioquest

What are the major categories of membrane lipids based on the structure and function?

Posted November 16, 2023


The three major categories of membrane lipids based on structure and function are phospholipids, glycolipids, and cholesterol. 

  1. The main type of lipids in the cell membrane is the phospholipids. These produce most of the cell membranes in the body, and are composed of a hydrophilic phosphate head and a hydrophobic fatty acid tail. More specifically, these lipids have a glycerol molecule, two fatty acids (part of the hydrophobic tail), and a phosphate group modified by an alcohol (part of the hydrophilic head). 
  2. Glycolipids are composed of a hydrophobic lipid tail and one or multiple hydrophilic sugar groups bound to a glycerol or a sphingolipid. These lipids are located in the outer leaflet of cell membranes, and play a role in maintaining membrane structure as well as regulating cell-cell communication. Glycolipids do this by behaving as receptors, as well as being anchors for proteins and modulating signal transduction. Glycolipids only make up less than 5% of the membrane. 
  3. Cholesterol makes up about 30% of the cell membrane. The main function of cholesterol is to regulate membrane fluidity. For example, at high temperatures, cholesterol stabilizes the cell membrane and raises its melting point. In contrast, at low temperatures cholesterol enters phospholipids and inhibits their ability to interfere with each other to avoid aggregation. In addition to this, cholesterol also affects factors such as the thickness, compressibility, and water penetration of the membrane. Cholesterol holds phospholipids together in a way so they do not pack too closely, or separate too far. As a result, cholesterol also prevents water from entering the membrane by reducing the voids. It also holds the membrane together when subjected to external factors such as temperature changes or pressure. 
Additional resources

The Lipid Bilayer

Plasma Membrane

iFluor® 488-Wheat Germ Agglutinin (WGA) Conjugate

Cell Navigator® Cell Plasma Membrane Staining Kit *Green Fluorescence*