Determiners of cell fates: the tricarboxylic acid cycle versusthe citrate-malate shuttle

The tricarboxylic acid(TCA)cycle identified in 1937 by Hans Adolf Krebs and William Arthur Johnson(also known as the Krebs cycle or citric acid cycle)is a central route for oxidative metabolism to generate cellular energy and intermediates for the biosynthesis of amino acids,lipids,and nucleic acids(Krebs and Johnson 1937).The TCA cycle connects carbohydrate,fat,and protein metabolism and converts these nutrient catabolism-derived acetyl-CoA into carbon dioxide and water,with the production of reduced NAD+(NADH),reduced flavin adenine dinucleotide(FADH2),and guanosine triphosphate(GTP).The generated NADH and FADH2 are,in turn,used by the oxidative phosphorylation pathway to generate energy-rich adenosine triphosphate(ATP)(Chakrabarty and Chandel 2021).