What are lipid rafts?
The plasma membrane has a nonrandom and asymmetrical distribution of lipid molecules within the bilayer. These lipids are mainly phospholipids, (glyco)-spingolipids, and cholesterol. Phospholipids tend to be loosely packed in bilayers, forming liquid disordered membrane. In contrast, sphingolipids have longer and more saturated alkyl chains than phospholipids and, in membranes, they show stronger lateral cohesion, generating tightly packed regions (liquid ordered domains). Cholesterol preferentially interacts with sphingolipids and occupies the space between the acyl chain, confering to these liquid ordered domains the capacity to float in the disordered phospholipid membrane. The combination of sphingolipids and cholesterol in small domains is responsible for the formation of lipid rafts microdomains.130 The size of rafts and their kinetics are still largely unknown, although several recent studies using different high-resolution microscopy techniques suggest that the basic raft units
