Lipid signalling

If you believe the fluid mosaic model of membrane structure, all the important jobs of the cell membrane, such as nutrient uptake, ion transport and transduction of hormonal signals, are attributable to membrane proteins rather than to the lipid bilayer in which they sit. But if all the membrane lipids do is to form a permeability barrier, you might expect them to have quite uniform structures. In fact, they are highly diverse, suggesting they have additional, more subtle roles in membrane function. One of the most important and best understood roles of membrane lipids and/or their products is to function as intracellular second messengers, which convey the information encoded in extracellular messengers, such as hormones, neurotransmitters and growth factors, to produce an appropriate cellular response. More recently, lipids have been shown to regulate essential functions of membranes themselves, providing crucial, yet poorly understood, signals which control the flow of membrane traffic between the major organelles of eukaryotic cells.