Apolipoproteins: the apoproteins in lipoproteins


 

In a wide sense, apoprotein is the term applied to the proteinic part (the one formed by amino acids) of conjugate proteins.

 

In a more narrow sense, and the one usually used in medical practice, apoprotein is the proteic part of a lipoprotein. From the technical point of view, it is more appropriate to call them “apolipoproteins”  

 

A common “motif” in the structure of apolipoproteins is the presence of amphipatic helixes that allow the interaction with the aqueous environment that surrounds the lipoprotein, and with the lipid interface of the lipoprotein.

 

In general, the apolipoproteins, besides contributing to the solubility of the lipoproteins as a whole, act as ligands for cellular receptors and as cofactors of enzymes related to the lipoprotein metabolism.

 

Apolipoproteins have been classified in families according to the size, distribution in lipoproteins and other characteristics.

 

The following table shows some important apolipoproteins, whose functions are known:

 

Apolipoprotein

Molecular Weight

Important Features

Apo A-1

29 000

Main protein in HDL; activates LCAT

Apo B-100

513 000

Main protein in LDL; it binds to LDL receptor

Apo C-II

8 800

Important in the composition of Chylomicrons and VLDL; activates Lipoprotein Lipase.

Apo E

34 000

Important in Chylomicrons, VLDL and IDL, allowing the binding of these lipoproteins to the hepatocytes.

 

 

More information about Apoproteins:

 

http://themedicalbiochemistrypage.org/lipoproteins.html#classification

 

 Related Posts:

 

Structure and Classification of Lipoproteins

 

 Metabolism of VLDL and Formation of IDL

 

 

Metabolism of Chylomicrons

 

 

 

4 thoughts on “Apolipoproteins: the apoproteins in lipoproteins

  1. Pingback: Some questions about Lipoproteins « The Biochemistry Questions Site

  2. Pingback: Metabolism of Very Low Density Lipoproteins (VLDL) and formation of Intermediate Density Lipoproteins (IDL) « The Biochemistry Questions Site

  3. Pingback: Structure and Classification of Lipoproteins « The Biochemistry Questions Site

  4. Pingback: Metabolism of chylomicrons « The Biochemistry Questions Site

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