Table 1.

The reactions, enzymes, transporters, and overall equation of the urea synthesis

ReactionsEnzymes
1Embedded ImageCarbamoyl phosphate synthetase 1
2Embedded ImageOrnithine transcarbamylase
3citrullinemit → citrullinecytCitrulline-ornithine transporter
4Embedded ImageArgininosuccinate synthetase
5Embedded ImageArgininosuccinase
6Embedded ImageArginase
7Embedded ImageCitrulline-ornithine transporter
Embedded Image
  • The synthesis of urea is the result of the cross talk between mitochondria and the cytosolic compartment: two mitochondrial reactions (reactions 1 and 2), three cytosolic reactions (reactions 4, 5, and 6), and the transport of two intermediates from mithocondria to cytosol and vice versa (steps 3 and 6).