The eukaryotic CAD protein is a trifunctional enzyme of carbamoylphosphate synthetase-aspartate transcarbamoylase-dihydroorotase, which catalyzes the first three steps of de novo pyrimidine nucleotide biosynthesis. Dihydroorotase (DHOase) catalyzes the third step, the reversible interconversion of carbamoyl aspartate to dihydroorotate.
Jiyao W et al.(2023). "The conserved domain database in 2023.",