Carbamoyl-phosphate synthetase 2, Aspartate transcarbamoylase, and Dihydroorotase (CAD)

The pyrimidine biosynthesis pathway consists of a series of enzymatic reactions that synthesize the core pyrimidine nucleotides (UMP, UDP, UTP, and CTP) from basic biochemical precursors[1][2][3]. In mammals, the first three speed-limiting steps are catalyzed by the multifunctional enzyme CAD, which includes domains for glutamine amidotransferase, carbamoyl phosphate synthetase II, aspartate transcarbamoylase, and dihydroorotase[2]. Subsequent steps involve dihydroorotate dehydrogenase and uridine monophosphate synthase[2][3]. Pyrimidine nucleotide synthesis is essential for DNA and RNA formation, cell membrane phospholipid synthesis, cell growth, and many metabolic functions. Pharmacological inhibitors of this pathway are clinically used to treat autoimmune diseases and are under investigation for cancer therapy[1][2]. The term "Pyrimidine biosynthesis pathway enzyme" describes *several distinct enzymes* (e.g., CAD, dihydroorotate dehydrogenase, UMPS), and is *not a standardized target name*; for further structured information, an exact enzyme such as "Carbamoyl-phosphate synthetase 2" or "CAD" should be specified[2][3].

Other names

CADpyrimidine biosynthetic enzymeCPSII (for carbamoyl phosphate synthetase II)

Inhibition of pyrimidine nucleotide synthesis, leading to reduced DNA/RNA synthesis, anti-proliferative and immunosuppressive effects