Figure 2. Mitochondrial metabolic network.

Many metabolic pathways converge to maintain energy output. While most cells use glucose/pyruvate for ATP synthesis, oxidation of fatty acids and amino acids can also be used in response to changes in the cellular environment and availability of substrates. These mechanisms ultimately converge onto the Krebs cycle to produce NADH and FADH₂, which in turn feed the mitochondrial ETC. Possible mechanisms of OxPhos deficiency in neurodegenerative diseases involving the AKT/PKB pathway and pyruvate metabolism are shown. G6P, glucose 6-phosphate.