Lipoproteins and Apolipoproteins
The human body is made mostly of water. Lipids (fats) can not travel freely through the intestinal lining, lymphatic system or blood stream because they will not dissolve in water. In order for these lipids to be absorbed through the intestinal tract and eventually travel through the blood stream, they have to be packaged within a special type of particle, called a lipoprotein. Lipoproteins have a surface that will interact with water and a core that is compatible with lipids.
Lipoproteins are the particles that help transport or carry triglycerides, cholesterol and fat soluble vitamins that are ingested into and through the blood stream. The lipoproteins include chylomicrons, Very Low Density Lipoproteins (VLDL), Intermediate Density Lipoproteins (IDL), Low Density Lipoproteins (LDL) and High Density Lipoproteins (HDL).
On the surface of a lipoprotein there are apolipoproteins that help to identify the specific lipoprotein. There are several types of apolipoproteins. The B apolipoproteins are affected in Abetalipoproteinemia (For more information, see: How does a mutation affect the MTP gene?) Apolipoprotein B has two main forms:
- apoB-48 - produced in the intestines
- apoB-100 - produced in the liver
This is an example of an LDL particle. The triglycerides and cholesteryl ester are packaged inside (fat soluble vitamins would also be packaged inside) while the apolipoproteins are on the surface.
Sources and Links:
http://web.indstate.edu/thcme/mwking/lipoproteins.html
http://www.uwgi.org/gut/smallbowel_10.asp
http://www.uwgi.org/gut/smallbowel_11.asp