Sterol O Acyltransferase (SOAT), also known as acyl-CoA:cholesterol acyltransferase (ACAT), is an enzyme that plays a key role in cholesterol metabolism. It is primarily responsible for the esterification of cholesterol, converting it into cholesterol esters. This enzymatic process is important for the efficient storage and transport of cholesterol within the body.
SOAT is primarily found in the endoplasmic reticulum of various cells, with the highest concentrations observed in the liver and intestines. It is involved in esterifying excess cholesterol, derived either from dietary sources or de novo synthesis, into cholesterol esters. This conversion allows cholesterol to be stored as an inert form within lipid droplets, preventing its toxicity and reducing its free concentration in cellular membranes.
The activity of SOAT is tightly regulated and is influenced by various factors, including cellular cholesterol levels and the presence of specific lipids. Increased cholesterol levels upregulate the expression of SOAT, promoting cholesterol esterification. Conversely, diminished cholesterol levels inhibit SOAT activity, facilitating the release of free cholesterol from esters.
Beyond cholesterol metabolism, SOAT also plays a role in other biological processes. It has been implicated in lipid droplet formation, cellular lipid homeostasis, and possibly modulating inflammation and the immune response. Additionally, mutations or dysregulation of SOAT activity have been associated with certain diseases, including atherosclerosis, obesity, and non-alcoholic fatty liver disease.
In summary, Sterol O Acyltransferase is an enzyme involved in the esterification of cholesterol. It helps regulate cholesterol levels and facilitates its storage and transport within cells.
