Carbamoyl-phosphate synthase [ammonia], mitochondrial (CPS1)

Carbamoyl-phosphate synthase [ammonia], mitochondrial (CPS1) is the rate-limiting enzyme of the urea cycle, primarily located in the mitochondrial matrix of hepatocytes and intestinal mucosal cells [4, 16]. It catalyzes the first committed step of the cycle, converting ammonia and bicarbonate into carbamoyl phosphate using two molecules of ATP, a process that requires N-acetylglutamate (NAG) as an obligate allosteric activator [1, 17]. By initiating the urea cycle, CPS1 plays a vital role in detoxifying ammonia, a neurotoxic byproduct of protein catabolism, and converting it into urea for renal excretion [7, 9]. Mutations in the CPS1 gene result in carbamoyl phosphate synthetase 1 deficiency, a rare and severe metabolic disorder characterized by life-threatening hyperammonemia and potential neurological damage [8, 20]. Therapeutically, CPS1 is targeted by carglumic acid, a synthetic analog of NAG that restores enzyme activity in patients with NAG synthase deficiency or certain organic acidemias [2, 3]. Additionally, CPS1 has emerged as a potential target in oncology, as some cancers overexpress the enzyme to support pyrimidine biosynthesis or manage intratumoral ammonia levels to promote growth [10, 11]. Experimental small-molecule inhibitors, such as H3B-120, are being developed to exploit these metabolic dependencies in cancer therapy [10, 14].

Other names

Carbamoyl-phosphate synthetase 1CPS1CPSICarbamoyl-phosphate synthase 1 (mitochondrial)Protein CPS1

Carglumic acid acts as a synthetic structural analog of N-acetylglutamate (NAG), the essential allosteric activator of CPS1, thereby binding to the enzyme and restoring its catalytic activity to facilitate ammonia detoxification [1, 2]. Experimental inhibitors target a novel allosteric pocket to block ATP hydrolysis or act as substrate mimics to suppress CPS1-dependent tumor growth [10, 13].