Lipoprotein Metabolism : Animation video

Composition of Lipoproteins:

  1. Consists of non-polar core (Mainly Triglycerides and cholesteryl esters)
  2. A single surface layer of amphipathic phospholipids and cholesterol
  3. Protein moiety are known as Apoprotein or Apolipoprotein
  4. Protein and lipid contents vary

Synthesis of Chylomicrons and VLDL: 

Metabolism of Chylomicrons:

  • Synthesised in intestine
  • Transport TAG (Triacylglycerol) to tissues and deliver remaining cholesterol & cholesterol ester to the liver.

Metabolism of VLDL, LDL and IDL:

  • VLDL is synthesised in liver and converted to LDL which contain an increased proportion of cholesterol & cholesteryl ester (due to loss of TAG).
  • Transport TAG and cholesterol from liver to tissues.
  • Cholesterol in LDL referred to as “bad cholesterol” since LDLs are implicated in atherosclerosis

Metabolism of HDL (High Density Lipoprotein):

  • HDL carries “used” cholesterol (as CE) back to the liver. Also donate some CE to circulating VLDL for redistribution to tissues.
  • HDL taken up by liver and degraded. The cholesterol is excreted as bile salts or repackaged in VLDL for distribution to tissues.
  • Cholesterol synthesis in the liver is regulated by the cholesterol arriving through HDL (and dietary cholesterol returned by chylomicron remnants).
  • Cholesterol (CE) in HDL is referred to as “good cholesterol”.