ACAT1(Acetyl-CoA acetyltransferase 1) is a mitochondrially localized enzyme that catalyzes the reversible formation of acetoacetyl-CoA from two molecules of acetyl-CoA. ACAT1 plays a significant role in ketone body metabolism and isoleucine processing. ACAT1 protein is located within mitochondria, where ACAT-1 facilitates acetyl-CoA conversion into acetoacetyl-CoA, a key step in ketone body synthesis and degradation. ACAT1′s mitochondrial localization is important for regulating energy metabolism, particularly during fasting or low carbohydrate intake, when ketone bodies serve as an alternative energy source for brain and heart tissues. Deficiencies in ACAT1 can lead to serious metabolic disorders, including β-ketothiolase deficiency, characterized by ketoacidotic attacks.