Apolipoprotein

In medicine and biochemistry, apolipoproteins are "protein components on the surface of lipoproteins. They form a layer surrounding the hydrophobic lipid core. There are several classes of apolipoproteins with each playing a different role in lipid transport and lipid metabolism. These proteins are synthesized mainly in the liver and the intestines."

Classification

• Apolipoprotein A (apo A) is the structural protein of high density lipoproteins (alpha-lipoproteins).
  • Apolipoprotein A-I (apo AI)
  • Apolipoprotein A-II
• Apolipoproteins B
  • Apolipoprotein B-100 (apo B-100) is the structural protein of LDL lipoproteins and VLDL lipoproteins.
  • Apolipoprotein B-48 (apo B-48) is the structural protein of chylomicrons.
• Apolipoproteins C
  • Apolipoprotein C-I
  • Apolipoprotein C-II
  • Apolipoprotein C-III
• Apolipoproteins D
• Apolipoproteins E.
  • Apolipoprotein E2
  • Apolipoprotein E3
  • Apolipoprotein E4

Role in dyslipidemias

Hypoalphalipoproteinemia

Mutations in the gene encoding apolipoprotein A-I is one cause of the familial dyslipidemia hypoalphalipoproteinemia.

Hyperlipoproteinemia Type I

Mutations in the gene encoding apolipoprotein C-II is one cause of the familial dyslipidemia hyperlipoproteinemia Type I.

Hyperlipoproteinemia Type III

Mutations in the gene encoding apolipoprotein E is the cause of the familial dyslipidemia hyperlipoproteinemia Type III.

Role as a diagnostic tests

Measurement of blood apolipoproteins and the ratio of apolipoprotein B / apolipoprotein A-I are alternatives to measuring cholesterol levels and the ratio of non–HDL cholesterol / HDL cholesterol in determining risk of vascular disease from atherosclerosis.