Figure 1. Functions of lipid rafts.

Figure 1

Functions of lipid rafts. This schematic view of a migrating cell (leading edge to the right) depicts the various functions that have been shown to involve lipid rafts. (1) Lipid rafts are involved in the sorting and trafficking of lipids and proteins to the plasma membrane of polarized cells. Vesicles budding from the Golgi are transported along microtubules to the front (red circles with thick border) or rear (green circles with thin border) of the cell. Certain types of endocytosis and exocytosis (unfilled vesicle and omega structure) also involve lipid rafts. It is possible that similar raft-dependent sorting methods are used by migrating cells to localize different sets of signaling components at the leading and trailing edges. (2) Many receptors and intracellular signaling molecules associate with lipid rafts and depend on these membrane microdomains for signal transduction events. Lipid rafts can serve as signaling platforms that enable the coupling of receptors to distinct pathways and can involve different variants of resident or recruited (induced association) mechanisms. (3) Regulation of the cytoskeleton is known to involve various proteins including the RhoGTPases as well as lipids such as certain phosphoinositides. Lipid rafts are thought to play a dynamic role in regulating the efficiency and membrane localization of these important protein and lipid regulators and thus the functions of the cytoskeleton. (4) Cell adhesion involves interactions between specific adhesion molecules on the cell with components of the extracellular matrix or other cells. Certain adhesion molecules associate with lipid rafts and their distribution on the cell may be regulated by lipid rafts and vice versa. It is important to consider that each lipid raft function can operate independent of the others during the overall functioning of the cell. It is also likely that some or all of the lipid raft functions operate in a coordinated fashion.

From: Membrane Lipid Rafts and Their Role in Axon Guidance

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