Involved in the urea cycle of ureotelic animals where the enzyme plays an important role in removing excess ammonia from the cell. 2 ATP + hydrogencarbonate + NH4(+) = 2 ADP + carbamoyl phosphate + 2 H(+) + phosphate Requires N-acetyl-L-glutamate (NAG) as an allosteric activator. Can form homooligomers (monomers as predominant form and dimers). The type-1 glutamine amidotransferase domain is defective. Undergoes proteolytic cleavage in the C-terminal region corresponding to the loss of approximately 12 AA residues from the C-terminus. Acetylation of Lys-287, Lys-603, Lys-841 and Lys-1291 is observed in liver mitochondria from fasted mice but not from fed mice. Succinylated at Lys-44, Lys-287 and Lys-1291. Desuccinylated at Lys-1291 by SIRT5, leading to activation. Glutarylated. Glutarylation levels increase during fasting. Deglutarylated by SIRT5 at Lys-55, Lys-219, Lys-412, Lys-889, Lys-892, Lys-915, Lys-1360 and Lys-1486, leading to activation. Was initially reported to be deacetylated by Sirt5 (PubMed:19410549). However, it was later shown that Sirt5 has poor deacetylase activity and mediates desuccinylation of Cps1 instead (PubMed:22076378).