These reactions mediate the synthesis of glutamate and glutamine from ammonia and TCA cycle intermediates and allow the utilization of the carbon atoms from these amino acids for glucose synthesis under fasting conditions. These reactions also provide a means to collect nitrogen, both as ammonia and as amino groups, and direct it towards urea synthesis. Transamination, the conversion of an amino acid to the corresponding alpha-keto acid coupled to the conversion of a molecule of 2-oxoglutarate (alpha-ketoglutarate) to glutamate, is the first step in the catabolism of most amino acids. Transamination reactions are freely reversible so they also provide a means to balance concentrations of various amino acids and 2-oxo (alpha-keto) acids in the cell (Felig 1975; Häussinger 1990; Owen et al. 1979).