beta-hydroxy-beta-methylglutaryl- synthase

β-·hy·drox·y·-·β-·meth·yl·glu·tar·yl·-· syn·thase

an enzyme in mitochondria that catalyzes the reaction of acetyl-CoA with acetoacetyl-CoA and water to form (S)-β-hydroxy-β-methylglutaryl-CoA and coenzyme A, a step required for both ketogenesis and steroidogenesis to occur.