Acyl CoA Cholesterol Acyltransferase, commonly known as ACAT, is an enzyme responsible for catalyzing the esterification of cholesterol in various tissues and cellular compartments. ACAT facilitates the conversion of free cholesterol, an important lipid molecule, into cholesterol esters, which are more hydrophobic and easily stored within cells. This enzyme plays a crucial role in maintaining cholesterol homeostasis in the body.
ACAT is predominantly found in the endoplasmic reticulum of various cells, including the liver, intestines, macrophages, and adrenal glands. It is involved in two major isoforms, namely ACAT1 and ACAT2, which differ in their tissue distribution and physiological functions.
ACAT1 primarily functions in cholesterol esterification for storage within lipid droplets of foam cells, which are formed during the development of atherosclerotic plaques. Meanwhile, ACAT2 is predominantly expressed in the intestines and participates in the packaging of cholesterol esters into chylomicrons for transport in the bloodstream.
The activity of ACAT is regulated by various factors, including dietary cholesterol intake, cholesterol levels in the cell, and hormonal signaling. Dysregulation of ACAT activity has been implicated in several diseases, including atherosclerosis, where excessive cholesterol esterification can contribute to the formation of plaque within arteries.
In summary, ACAT is an enzyme that catalyzes the esterification of cholesterol, converting it into a more storage-friendly form. It is a key component in maintaining cholesterol balance within cells and tissues.
