L-glutamate and L-glutamine are non-essential amino-acids. In mitochondrial glutaminolysis, L-glutamine is converted to L-glutamate by Gls and then to 2-oxoglutarate, an intermediate of the tricarboxylic acid (TCA) cycle. L-glutamate deamidation can be catalyzed either by L-glutamate dehydrogenase Gdh, which converts glutamate into ammonium and 2-oxoglutarate, or by transaminases such as Alat or Got2, which produce 2-oxoglutarate and L-alanine or L-aspartate. Additional cytosolic and mitochondrial enzymes, including Gs1, Gs2 and Glts participate in the interconversion between L-glutamate and L-glutamine which plays an essential role in nitrogen metabolism. Besides their role in protein synthesis, L-glutamine is involved in the biosynthesis of purines, pyrimidines, L-asparagine, NAD(+) and UDP-N-acetylglucosamine, whereas L-glutamate is required for the production of GABA, L-serine, L-proline, L-alanine, glutathione and is part of the malate-aspartate shuttle. In addition, L-glutamate acts as a neurotransmitter and is used for the glutamylation of tubulin and the tetrahydrofolate cofactor. (Adapted from PMID:32943735.)