Q. What is low - density lipoprotein receptor pathway?

Ans.

The increasing cellular free cholesterol generated regulates the activities of two enzymes that are of crucial importance in cholesterol homeostasis. HMG-CoA reductase (the major rate-determining enzyme in the cholesterol synthetic pathway) is inhibited, reducing cholesterol synthesis. Acyl CoA: cholesterol acyl transferase (ACAT) is activated, thus facilitating the re-esterification of cholesterol to cholesterol ester.

Thus the LDL receptor pathway is a closely integrated system by which cells acquire cholesterol and cellular cholesterol homeostasis is maintained. The therapeutic potential of interrupting this pathway will become apparent when the statin drugs which are inhibitors of HMG-CoA reductase are discussed.

It is the activity of LDL receptors in the liver that largely controls plasma LDL levels. Approximately 70 per cent of LDL is removed by this pathway.