Glutamine Metabolism (None)

Glutamine metabolism refers to the cellular processes involving the synthesis, transport, utilization, and breakdown of glutamine—a non-essential amino acid that becomes conditionally essential during periods of rapid cell proliferation or physiological stress. Glutamine is the most abundant free amino acid in human blood and plays a central role in nitrogen balance, energy production, biosynthesis of macromolecules, redox homeostasis, and cellular signaling. Key enzymes include glutamine synthetase (GS), phosphate-dependent glutaminase (GLS), glutamate dehydrogenase (GDH), and transaminases. ASCT2/SLC1A5 is the main transporter responsible for importing extracellular glutamine. During illness or rapid proliferation (e.g., cancer), demand outpaces endogenous supply—glutamine becomes conditionally essential. Many cancer cells are "addicted" to exogenous glutamine. In immune function: critical fuel source for lymphocytes/macrophages.

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