Carbamoyl phosphate synthetase (glutamine-hydrolysing) () is an enzyme that catalyzes the reactions that produce carbamoyl phosphate in the cytosol (as opposed to type I, which functions in the mitochondria). Its systemic name is hydrogen-carbonate:-glutamine amido-ligase (ADP-forming, carbamate-phosphorylating).
In pyrimidine biosynthesis, it serves as the rate-limiting enzyme and catalyzes the following reaction: 2 ATP + -glutamine + HCO3– + H2O 2 ADP + phosphate + -glutamate + carbamoyl phosphate (overall reaction) (1a) -glutamine + H2O -glutamate + NH3 (1b) 2 ATP + HCO3– + NH3 2 ADP + phosphate + carbamoyl phosphate
It is activated by ATP and PRPP and it is inhibited by UTP (Uridine triphosphate) Neither CPSI nor CPSII require biotin as a coenzyme, as seen with most carboxylation reactions.
It is one of the four functional enzymatic domains coded by the CAD gene. The CAD gene is a large gene. It uses a single strand to code for these enzyme jobs. It is classified under .
See also
Carbamoyl phosphate synthetase I Carbamoyl phosphate synthetase III
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