What is a lipid raft and what is its function?

Lipid rafts are plasma membrane microdomains enriched in cholesterol and sphingolipids that are involved in the lateral compartmentalization of molecules at the cell surface. Internalization of ligands and receptors by these domains occurs via a process defined as raft-dependent endocytosis.

What makes a lipid raft?

Rafts are small platforms, composed of sphingolipids and cholesterol in the outer exoplasmic leaflet, connected to phospholipids and cholesterol in the inner cytoplasmic leaflet of the lipid bilayer. These assemblies are fluid but more ordered and tightly packed than the surrounding bilayer.

What is the function of membrane rafts?

Membrane rafts are dynamic, small (10–200 nm) domains enriched with cholesterol and sphingolipids that compartmentalize cellular processes. Rafts participate in roles essential to the lifecycle of different viral families including virus entry, assembly and/or budding events.

What do lipid rafts carry?

Membrane Microdomains Cholesterol rich domains in membranes are called lipid rafts and the rest are called non-lipid rafts. Lipid rafts serve as signaling platforms for several signaling molecules such as G-protein-subunits, enzymes, and adaptor proteins.

What is the function of phosphatidylcholine?

Phosphatidylcholine (PC) is an important component of the mucosal layer of the colon and acts as a surfactant within the mucus to create a hydrophobic surface to prevent bacterial penetrance.

Does cholesterol stabilize lipid rafts?

Rafts also appear to be enriched in cholesterol and lipids with saturated fatty acids, especially sphingolipids, which would lead to regions of enhanced packing and reduced fluidity. Cholesterol would stabilize packing in spaces created with lipids with large head groups.

Are lipid rafts real?

Tiny structures made of lipid molecules and proteins have been believed to wander within the membrane of a cell, much like rafts on the water. This “raft hypothesis” has been widely accepted, but now scientists at TU Wien (Vienna) have shown that in living cells these lipid rafts do not exist.

Where are Glycosphingolipids found?

eukaryotic plasma membranes
Glycosphingolipids, found in eukaryotic plasma membranes, are comprised of a ceramide backbone that has a glycan covalently bound to it. It is thought that glycosphingolipids act to modulate membrane-protein function, as well as playing a role in cell-cell communication.

What is the role of caveolin?

Caveolin-1 (CAV1), an integral membrane protein, is the principal component of caveolae in membranes and is involved in multiple cellular functions such as endocytosis, cholesterol homeostasis, signal transduction, and mechanoprotection.

Is phosphatidylcholine a lipid?

Phosphatidylcholines are the major lipid of lung surfactant.

What type of lipid is phosphatidylcholine?

Phosphatidylcholine (PC) and sphingomyelin (SM) are the two major phospholipids of HDL. These lipids are located in the surface monolayer of the particle together with the free cholesterol and apoA-I.

Do lipid rafts decrease fluidity?

Lipid rafts are specialized membrane microdomains that serve as organizing centers for assembly of signaling molecules, influence membrane fluidity and trafficking of membrane proteins, and regulate different cellular processes such as neurotransmission and receptor trafficking.