Metabolism of HDL and LCAT Function

What is the primary function of lecithin-cholesterol acyl-transferase (LCAT) in HDL metabolism?

How does HDL primarily acquire free cholesterol from other sources?

What happens to HDL particles after they uptake free cholesterol?

What role does apoprotein A play in HDL metabolism?

What is the ultimate fate of cholesteryl esters taken up by HDL in the liver?

Metabolism of HDL

High-density lipoproteins (HDL) are synthesized in the liver and intestine as nascent HDL.
Nascent HDL contains free cholesterol, phospholipids (primarily lecithin), and apoproteins such as A, CII, and E.

Role of LCAT in HDL metabolism

Lecithin-cholesterol acyl-transferase (LCAT) is a plasma enzyme that catalyzes the esterification of free cholesterol using fatty acids from lecithin.
LCAT activity is promoted by apoprotein A.
HDL can accept free cholesterol from other circulating lipoproteins and peripheral cell membranes.
Any free cholesterol taken up by HDL undergoes esterification through the action of LCAT, resulting in spherical HDL particles.
Spherical HDL particles, containing cholesteryl esters, enter hepatocytes via receptor-mediated endocytosis.
Within the liver, cholesteryl esters are degraded to cholesterol.
The cholesterol derived from cholesteryl esters is utilized for bile acid synthesis, lipoprotein formation, or excreted into bile.

Cardioprotective function of HDL

HDL is referred to as "good cholesterol" due to its positive role in lipid metabolism and cardiovascular health.

This quiz covers the essential roles of high-density lipoproteins (HDL) in cholesterol metabolism, including their synthesis and interaction with lecithin-cholesterol acyl-transferase (LCAT). It examines how HDL particles are formed, how they accept cholesterol, and their ultimate fate in the liver. Test your understanding of lipid metabolism and the significance of HDL in cardiovascular health.