L-Glutamine is important as a precursor for peptide and protein synthesis, amino sugar synthesis, purine and pyrimidine and thus nucleic acid and nucleotide synthesis, and also provides a source of carbons for oxidation in some cells. L-Glutamine is the most abundant extracellular amino acid in vivo (0.7 mM compared to an approximate L-glutamate concentration of 20 µM).
In BRIN-BD11 cells, culture for 24 h with 10 mM L-Glutamine compared with 1 mM resulted in substantial changes in gene expression with 148 genes upregulated more than 1.8-fold, and 18 downregulated more than 1.8-fold, including many genes involved in cellular signaling, metabolism, gene regulation, and the insulin-secretory response. L-Glutamine increases the activity of the Ca2+ regulated phosphatase calcineurin and the transcription factor Pdx1.