• Comprised of carbamoyl phosphate and aspartate
• From carbamoyl phosphate synthetase II
• Catalyzes the rate limiting step in pyrimidine de novo synthesis
• Cytosolic enzyme that synthesizes carbamoyl phosphate
• Synthesis of carbamoyl phosphate

1. Bicarbonate uses ATP to become carboxyphosphate Phosphorylation
2. Carboxyphosphate + NH3 -> Carbamic acid Amination
3. Carbamic acid + ATP -> ADP + Carbamoyl phosphate Phosphorylation

• This enzyme works by channeling
• Diminishes loss of substrate by diffusion and non-productive reactions (hydrolysis)
• There’s one in the urea cycle too
• Gln + CO2 + 2 ATP + H2O -> carbamoyl phosphate + Glu + 2 ADP + Pi