ABSTRACT
Lipids are essential for numerous aspects of cellular biology, including energy homeostasis, reproductive andorgan physiology. The major plasma lipids are cholesterol and triglycerides. Cholesterol is a constituent of membranes and triglycerides are an energy source. The human bodyhas evolved a sophisticated lipoprotein transport system todeliver cholesterol and triglycerides to a variety of tissues in order to meet the different demands. Lipoproteins contain a hydrophobic core of cholesterol ester and triglycerides and an amphiphilic coat consisting of phospholipids, free cholesterol and apolipoproteins. They are classied into four major subtypes depending on the size, density, protein and lipid content (Lindgren et al. 1972). The apoproteins, the protein components of the lipoproteins, serve as membrane stabilizers. They also serve as cofactors in the activation of enzymes that modify the lipoproteins and interact with specic receptors that remove lipoproteins from the circulation. In addition, they are required for synthesis and secretion of certain lipoproteins.
