-Hydroxy--Methylglutaryl-CoA (HMG-CoA)

HMG-CoA is formed in cells as a product of a reaction catalyzed by HMG-CoA synthase. The molecule has two primary metabolic fates. One pathway, which leads to ketone bodies, occurs in the mitochondria. It starts with a reaction catalyzed by HMG-CoA lyase.

Another pathway involving HMG-CoA leads to formation (ultimately) of cholesterol and other steroids. It occurs in the cytoplasm and is initiated by a reaction catalyzed by HMG-CoA reductase.