(Science: amino acid) One of the 20 _ amino acids commonly found in proteins. Plays a central role in amino acid metabolism, acting as precursor of glutamine, proline and arginine. Also acts as amino group donor in synthesis by transamination of alanine from pyruvate and aspartic acid from oxaloacetate. Glutamate is also a neurotransmitter, the product of its decarboxylation is the inhibitory neurotransmitter amino butyrate (GABA). An amino acid occurring in proteins; important in the nitrogen metabolism of plants; used in monosodium glutamate to enhance the flavor of meats.One of the 20 amino acids that are commonly found in proteins.