Taxonomic distribution of proteins containing CPSase_sm_chain domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing CPSase_sm_chain domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Mammalian carbamyl phosphate synthetase (CPS). DNA sequence and evolutionof the CPS domain of the Syrian hamster multifunctional protein CAD.

Simmer JP, Kelly RE, Rinker AG Jr, Scully JL, Evans DR
J Biol Chem. 1990; 265: 10395-402

Glutamine-dependent carbamoyl-phosphate synthetase (EC 6.3.5.5) catalyzesthe first step in de novo pyrimidine biosynthesis. The mammalian enzyme ispart of a 240-kDa multifunctional protein which also has the second(aspartate carbamoyltransferase, EC 2.1.3.2), and third (dihydroorotase,EC 3.5.2.3) activities of the pathway. Shigesada et al. (Shigesada, K.,Stark, G.R., Maley, J.A., and Davidson, J.N. (1985) Mol. Cell Biol. 175,1-7) produced a truncated cDNA clone from a Syrian hamster cell line thatcontained most of the coding region for this protein. We have completedsequencing this clone, known as pCAD142. The cDNA insert contained all ofthe coding region for the glutaminase (GLN) and carbamyl phosphatesynthetase (CPS) domains but lacked a short amino-terminal segment. Bycomparing the primary structure of the mammalian chimera to monofunctionalproteins we have identified the borders of the functional domains. The GLNdomain is 21 kDa, close to the size of the functionally similarpolypeptide products of the Escherichia coli pabA and hisH genes. Thedomain has the three regions of homology common to trpG-type glutamineamidotransferases, as well as a fourth region specific to the carbamylphosphate synthetases. The CPSase domain is similar to other reportedCPSases in size (120 kDa), primary structure (37-67% amino acid identity),and homology between its amino and carboxyl halves. Analysis of thenucleotide and amino acid sequence identities among the various carbamylphosphate synthetases suggests that the gene fusion which joined the GLNand CPS domains was an early event in the evolution of eukaryoticorganisms and that the Saccharomyces cerevisiae enzyme consisting ofseparate subunits arose by defusion from an ancestral multifunctionalprotein.