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. Author manuscript; available in PMC: 2018 Feb 7.
Published in final edited form as: Cell Metab. 2017 Feb 7;25(2):262–284. doi: 10.1016/j.cmet.2016.12.022

Fig. 1. Metabolism of ketone bodies.

Fig. 1

(A) Ketogenesis within hepatic mitochondria is the primary source of circulating ketone bodies, requiring the fate-committing enzyme HMGCS2. Ketone bodies are secreted, and their primary metabolic fate is terminal oxidation within mitochondria of extrahepatic tissues through reactions that require the enzyme SCOT. mThiolase (mitochondrial thiolase); e−, electrons emanating from TCA cycle as NADH and FADH2; ETC, electron transport chain. Question marks reflect uncertainty of the mechanism responsible for transporting ketones across the inner mitochondrial membrane. (B) Ketone body metabolism is integrated through mitochondrial and cytoplasmic metabolic pathways. Cytoplasmic lipogenesis and cholesterol synthesis are nonoxidative metabolic fates of ketone bodies. mThiolase or cThiolase activity is encoded by at least 6 genes: ACAA1, ACAA2 (encoding an enzyme known as T1 or CT), ACAT1 (encoding T2), ACAT2, HADHA, and HADHB. ACSS2, acetyl-CoA synthetase 2 (cytoplasmic).