The interplay between amino acids, carbon substrates, and nonenergetic functions. Please note for simplicity, polyamine synthesis, mitochondrial folate cycle, and citrate export to cytoplasm for fatty acid synthesis via acetyl-CoA are omitted. Red lines denote reactions that add to central carbon oxidation; green lines denote lines that will divert from central carbon oxidation. 3-PG, 3-phosphoglyceric acid; AS, argininosuccinate; G6P, glucose 6-phosphate; m-THF, methyl-tetrahydrofolate; me THF, methenyl-tetrahydrofolate; OAA, oxaloacetate; THF, tetrahydrofolate.