Acetyl-CoA acetyltransferase; part of the first module of ergosterol biosynthesis pathway that includes the early steps of the pathway, conserved across all eukaryotes, and which results in the formation of mevalonate from acetyl-coenzyme A (acetyl-CoA) (By similarity). Erg10 catalyzes the formation of acetoacetyl-CoA from acetyl-CoA (By similarity). The first module starts with the action of the cytosolic acetyl-CoA acetyltransferase eg10 that catalyzes the formation of acetoacetyl-CoA. The hydroxymethylglutaryl-CoA synthases erg13 then condenses acetyl-CoA with acetoacetyl-CoA to form HMG-CoA. The rate-limiting step of the early module is the reduction to mevalonate by the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductases hcs1 (Probable). 2 acetyl-CoA = acetoacetyl-CoA + CoA Metabolic intermediate biosynthesis; (R)-mevalonate biosynthesis; (R)-mevalonate from acetyl-CoA: step 1/3. Homotetramer. Belongs to the thiolase-like superfamily. Thiolase family.