Besides energy storage and bilayer formation, lipids have several other important functions in the cell.
Anchors for membrane-associated proteins
Many proteins are anchored to membranes in the cell by the covalent attachment of a fatty acid. For example, the viral protein src causes cancer in several organisms. An amide bond is formed between the Gly residue and myristic acid, a fatty acid found in cell membranes. The covalent bond keeps the protein associated with the membrane. The ability of src to cause cancer is blocked if the formation of this peptide bond is prevented.