Catalyzes the second step of the urea cycle, the condensation of carbamoyl phosphate with L-ornithine to form L-citrulline (PubMed:6372096, PubMed:8112735, PubMed:2556444). The urea cycle ensures the detoxification of ammonia by converting it to urea for excretion (PubMed:2556444). carbamoyl phosphate + L-ornithine = H(+) + L-citrulline + phosphate Negatively regulated by lysine acetylation. Nitrogen metabolism; urea cycle; L-citrulline from L-ornithine and carbamoyl phosphate: step 1/1. Homotrimer. Mainly expressed in liver and intestinal mucosa. Acetylation at Lys-88 negatively regulates ornithine carbamoyltransferase activity in response to nutrient signals. The disease is caused by variants affecting the gene represented in this entry. Belongs to the aspartate/ornithine carbamoyltransferase superfamily. OTCase family.