acylCoAcholesterol

AcylCoAcholesterol is a term used to describe cholesteryl esters, the esters formed when a fatty acyl group is transferred from acyl-CoA to cholesterol. In biochemistry, these esters serve as a storage form of cholesterol and are produced by the enzyme acyl-CoA:cholesterol acyltransferase (ACAT, also called SOAT).

The esterification reaction is catalyzed by two isozymes: ACAT1 (SOAT1) and ACAT2 (SOAT2). ACAT1 is expressed broadly in many tissues, while ACAT2 expression is enriched in the liver and intestine. The fatty acyl group donor is typically a long-chain acyl-CoA, and the product is a cholesteryl ester plus CoA.

Cholesteryl esters are hydrophobic and are stored in cytosolic lipid droplets within cells. They also form the core lipid of circulating lipoproteins, such as low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles, where they contribute to cholesterol transport and storage in the bloodstream.

Physiological roles include maintaining cellular cholesterol homeostasis, supplying cholesterol for membrane synthesis and steroid hormone production, and enabling efficient storage when dietary intake or synthesis exceeds immediate needs. Cholesteryl esters thus help regulate cholesterol distribution between cells and tissues.

Pathological accumulation of cholesteryl esters in macrophage foam cells is a hallmark of atherosclerosis. Therapeutic approaches have explored ACAT inhibitors, but clinical outcomes have been variable and context-dependent, with ongoing research into tissue-specific effects and potential benefits. In laboratory practices, cholesteryl ester content is measured to assess lipid metabolism and esterification activity.