Reaction: a long-chain acyl-CoA + a sterol = CoA + a long-chain 3-hydroxysterol ester
Other name(s): cholesterol acyltransferase; sterol-ester synthase; acyl coenzyme A-cholesterol-O-acyltransferase; acyl-CoA:cholesterol acyltransferase; ACAT; acylcoenzyme A:cholesterol O-acyltransferase; cholesterol ester synthase; cholesterol ester synthetase; cholesteryl ester synthetase; SOAT1 (gene name); SOAT2 (gene name); ARE1 (gene name); ARE2 (gene name); acyl-CoA:cholesterol O-acyltransferase
Systematic name: long-chain acyl-CoA:sterol O-acyltransferase
Comments: The enzyme catalyses the formation of sterol esters from a sterol and long-chain fatty acyl-coenzyme A. The enzyme from yeast, but not from mammals, prefers monounsaturated acyl-CoA. In mammals the enzyme acts mainly on cholesterol and forms cholesterol esters that are stored in cytosolic droplets, which may serve to protect cells from the toxicity of free cholesterol. In macrophages, the accumulation of cytosolic droplets of cholesterol esters results in the formation of `foam cells', a hallmark of early atherosclerotic lesions. In hepatocytes and enterocytes, cholesterol esters can be incorporated into apolipoprotein B-containing lipoproteins for secretion from the cell.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9027-63-8
References:
1. Spector, A.A., Mathur, S.N. and Kaduce, T.L. Role of acylcoenzyme A: cholesterol O-acyltransferase in cholesterol metabolism. Prog. Lipid Res. 18 (1979) 31-53. [PMID: 42927]
2. Taketani, S., Nishino, T. and Katsuki, H. Characterization of sterol-ester synthetase in Saccharomyces cerevisiae. Biochim. Biophys. Acta 575 (1979) 148-155. [PMID: 389289]
3. Lee, O., Chang, C.C., Lee, W. and Chang, T.Y. Immunodepletion experiments suggest that acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) protein plays a major catalytic role in adult human liver, adrenal gland, macrophages, and kidney, but not in intestines. J. Lipid Res. 39 (1998) 1722-1727. [PMID: 9717734]
4. Yang, H., Cromley, D., Wang, H., Billheimer, J.T. and Sturley, S.L. Functional expression of a cDNA to human acyl-coenzyme A:cholesterol acyltransferase in yeast. Species-dependent substrate specificity and inhibitor sensitivity. J. Biol. Chem 272 (1997) 3980-3985. [PMID: 9020103]
5. Chang, C.C., Lee, C.Y., Chang, E.T., Cruz, J.C., Levesque, M.C. and Chang, T.Y. Recombinant acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) purified to essential homogeneity utilizes cholesterol in mixed micelles or in vesicles in a highly cooperative manner. J. Biol. Chem 273 (1998) 35132-35141. [PMID: 9857049]
6. Das, A., Davis, M.A. and Rudel, L.L. Identification of putative active site residues of ACAT enzymes. J. Lipid Res. 49 (2008) 1770-1781. [PMID: 18480028]