The plasma membranes of cells contain combinations of glycosphingolipids and protein receptors organized in glycolipoprotein microdomains termed lipid rafts . [ 1 ] [ 2 ] [ 3 ] These specialized membrane microdomains compartmentalize cellular processes by serving as organizing centers for the assembly of signaling molecules , influencing membrane fluidity and membrane protein trafficking, and regulating neurotransmission and receptor trafficking. [ 3 ] [ 4 ] Lipid rafts are more ordered and tightly packed than the surrounding bilayer , but float freely in the membrane bilayer. [ 5 ] Although more common in plasma membrane, lipid rafts have also been reported in other parts of the cell, such as Golgi and lysosomes .