Serum lipids and lipoproteins: a brief review of the composition, transport and physiological functions

Abstract

The dietary fats are composed primarily of triacylglycerols and some amount of phospholipids and cholesterol. Being hydrophobic in nature, these are insoluble in water, and hence cannot be transported in the blood plasma per se; to enable these lipids to be transported by the blood stream to various peripheral tissues, nature has devised the technique of making these soluble by binding them to proteins. These proteins involved in lipid transport are known as apolipoproteins, and the protein-lipid particle is known as lipoprotein. Thus, lipoproteins can be considered to be the primary transport mechanism to carry lipids from the alimentary tract to various parts of the body. Lipoproteins have gained prominence in medical field over the past few decades because of their role in the aetio-pathogenesis of cardiovascular diseases, principally atherosclerosis which is the cause of coronary artery disease and myocardial infarction. The various types and sub-types of lipoproteins have been found to have differing and even opposing roles in the development of arterial diseases. An understanding of the differing populations of lipoproteins, the associated proteins and other enzymes, and the myriad variety of inter-actions among themselves and with body cells is vital to our understanding the pathways involved in the development of cardio-vascular disorders and in determining the precise steps where pharmacological interventions can be introduced.