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N-Acetyl-L-glutamate (NAGS) is a molecule that plays a crucial role in the urea cycle, a metabolic pathway responsible for detoxifying ammonia in the body. Specifically, NAGS acts as a vital allosteric activator of carbamoyl phosphate synthetase I (CPS1), the rate-limiting enzyme in the urea cycle. Without NAGS, CPS1 activity is significantly reduced, leading to impaired ammonia removal.

The primary function of NAGS is to stimulate CPS1, which catalyzes the condensation of bicarbonate and ammonia to form carbamoyl phosphate. This initial step is essential for channeling nitrogen, derived from amino acid catabolism, into the urea cycle. The urea cycle then converts this nitrogen into urea, which is ultimately excreted from the body.

Genetic defects in the NAGS gene can lead to a rare metabolic disorder known as NAGS deficiency. This deficiency results in an accumulation of ammonia in the blood (hyperammonemia), which can cause severe neurological damage, especially in infants. Treatment for NAGS deficiency typically involves dietary protein restriction and the administration of N-acetylglutamate itself, which can bypass the enzymatic defect and effectively activate CPS1, thereby promoting ammonia detoxification. NAGS is also synthesized endogenously in the liver, highlighting its integral role in maintaining nitrogen homeostasis.