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Introduction
Lipoprotein Structure
Chylomicron metabolism
Metabolism of V-LDL and LDL
Distribution of cholesterol
Normal serum lipid concentrations and therapeutic thresholds
Fredrickson/WHO classification of HPL
Primary HPL (type IIa) involving HC
Primary HPLs (types IIb and III) that combine HC with hypertriglyceridaemia
Hypolipoproteinaemias
Secondary hyperlipoproteinaemias
Hypolipoproteinaemias
References
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Author biography


Lipoprotein Structure

Lipoprotein molecules have a globular general structure (see Figure 1) and are formed of:

  • more polar lipids (phospholipids and free cholesterol), which are located on the outer part of the lipoprotein with their charged groups pointing out towards the water molecules. Thus, structurally, the surface of a lipoprotein resembles the outer half of a cell membrane;
  • more hydrophobic lipids (esterified cholesterol and triglycerides), which are located in the core of the lipoprotein particle. These form a central droplet, to which the phospholipids and free cholesterol surface-coating molecules are anchored by their hydrophobic regions;
  • proteins (in lipoproteins these are the apolipoproteins), a group with immense structural diversity. These can span the region between the central core and the outer envelope, and have part of their structure exposed at the surface. Some have a largely structural role, while others are major metabolic regulators; and
  • enzymes (eg, lecithin:cholesterol acyltransferase [LCAT], phospholipase A2 and paraoxonase).
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Figure 1. Lipoprotein structure







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