What is the Role of Cholesterol in a Cell Membrane?

Most people know about cholesterol because of its ability to cause heart disease and atherosclerosis. However, cholesterol has a number of other important functions in the body. Aside from its role in making steroid hormones, cholesterol is also an important component of the membrane that surrounds all cells in the human body.

Cell Membrane Components

Cells are surrounded by a membrane that is made out of lipids. Specifically, the cell membrane contains a double layer of lipids called phospholipids (because they have a phosphate molecule attached to them). Cholesterol is another lipid which can be found within the cell membrane and, according to Choleterol-and-Health.com, it can represent 50 percent of the membrane in some cells.

Support

One role of cholesterol is to help give the cell membrane extra support. Cholesterol is more rigid than some of the other lipids in the membrane. As Cytochemistry.net explains, cholesterol helps to immobilize some of the lipid molecules around them. This extra rigidity makes the cell membrane stronger and makes it harder for small molecules to pass through the membrane. The presence of cholesterol allows the cell membrane to be strong enough to hold the cell together and to serve as an effective barrier to ions.

Membrane Fluidity

Despite the fact that cholesterol is more rigid than some of its neighboring lipids, cholesterol also has an important role in keeping the cell membrane fluid. Cholesterol helps generate some extra space between the lipids, which keeps them from gelling together into their "crystalline" state. This allows lipids to move freely throughout the membrane as needed.

Lipid Rafts

An article in PNAS (Proceeding of the National Academy of Sciences) explains that cholesterol also has an important role in the construction of special parts of cell membranes called lipid rafts. Lipid rafts are made up of high amounts of cholesterol and special kinds of lipids called sphingolipids. These rafts allow some sections of the membrane to be distinct from other areas.

Lipid Raft Function

Lipid rafts are important for many cellular actions. Some lipid rafts are needed in order to export proteins out of the cell. Other lipid rafts are used to anchor specific proteins in the membrane and keep protein clusters together. Some pathogens (like viruses and bacteria) also target lipid rafts in order to get into the cell.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.
references
Load Comments
PARTNER & LICENSEE OF THE LIVESTRONG FOUNDATION

Copyright © 2019 Leaf Group Ltd. Use of this web site constitutes acceptance of the LIVESTRONG.COM Terms of Use , Privacy Policy and Copyright Policy . The material appearing on LIVESTRONG.COM is for educational use only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. LIVESTRONG is a registered trademark of the LIVESTRONG Foundation. The LIVESTRONG Foundation and LIVESTRONG.COM do not endorse any of the products or services that are advertised on the web site. Moreover, we do not select every advertiser or advertisement that appears on the web site-many of the advertisements are served by third party advertising companies.