Glutamine
In human blood, glutamine is the most abundant free amino acid.
Dicarboxylic aminoaciduria
Dicarboxylic aminoaciduria is a rare form of aminoaciduria (1:35 000 births) which is an autosomal recessive disorder of urinary glutamate and aspartate due to genetic errors related to transport of these amino acids. Mutations resulting in a lack of expression of the "SLC1A1" gene, a member of the solute carrier family, are found to cause development of dicarboxylic aminoaciduria in humans. SLC1A1 encodes for EAAT3 which is found in the neurons, intestine, kidney, lung, and heart. EAAT3 is part of a family of high affinity glutamate transporters which transport both glutamate and aspartate across the plasma membrane.