Functional roles of lipids in biological membranes

Abstract Membranes are complex structures composed primarily of proteins and lipids stabilised by dynamic cooperative non-covalent interactions. During the course of evolution, proteins and lipids have co-evolved following a set of interdependent rules based on their respective physical and chemical properties that govern the biogenesis, organisation and function of membrane proteins. Our understanding of the function of membrane lipids has progressed from a static canonical role as a cell barrier matrix supporting membrane proteins to dynamic roles as molecular chaperones, topological determinants, allosteric ligands and organisers of complex biological machines. Combined molecular genetic and biochemical approaches have uncovered a picture of biological membranes in which lipids and proteins interact dynamically, reversibly, temporally and spatially depending on different cellular circumstances and demands. Membrane proteins can undergo conformational changes and even transmembrane re-organisation in response to variations in the lipid environment or posttranslational modification without a severe thermodynamic cost. Lipids can contribute to execution of genetic code by decoding protein sequences subject to a variable lipid composition.