Background：The de novo synthesis of pyrimidine nucleotides is required for mammalian cells to proliferate. This gene encodes a trifunctional protein which is associated with the enzymatic activities of the first 3 enzymes in the 6-step pathway of pyrimidine biosynthesis： carbamoylphosphate synthetase （CPS II）, aspartate transcarbamoylase, and dihydroorotase. This protein is regulated by the mitogen-activated protein kinase （MAPK） cascade, which indicates a direct link between activation of the MAPK cascade and de novo biosynthesis of pyrimidine nucleotides. Alternative splicing results in multiple transcript variants encoding different isoforms.
