Lipid raft

Lipid rafts are described as specialized structures, or as dynamic cell membrane microdomains. They are believed to be glycolipoprotein lipid microdomains containing a combination of glycosphingolipids, cholesterol, and protein that is recruited, including receptors. Although initially described in the plasma membrane and Golgi membrane, lipid rafts have also been reported in other endomembranes such as lysosomes. However, it is questionable whether it is appropriate to label any such structures lipid rafts, given that their composition and properties deviate considerably from the original lipid raft theory. The lipid raft theory has a history of being redefined in response to contradictory evidence. Cholesterol is an intrinsic component of the cell membrane where it maintains the stability and fluidity of the membrane. Cholesterol regulates protein signaling as a major organiser of lipid rafts. Lipid rafts serve as organising centers for assembling signalling molecules, and influence membrane protein trafficking, to regulate different cell processes such as neurotransmission and receptor trafficking. Lipid rafts are more ordered and tightly packed than the surrounding bilayer, but float freely within the membrane bilayer. Some researchers propose that lipid rafts are an incidental feature of only incidental physiological significance.