Carbamoyl-phosphate synthase small chain, CPSase domain
SMART accession number:
SM01097
Description:
The carbamoyl-phosphate synthase domain is in the amino terminus of protein. Carbamoyl-phosphate synthase catalyses the ATP-dependent synthesis of carbamyl-phosphate from glutamine or ammonia and bicarbonate. This important enzyme initiates both the urea cycle and the biosynthesis of arginine and/or pyrimidines (PUBMED:1972379). The carbamoyl-phosphate synthase (CPS) enzyme in prokaryotes is a heterodimer of a small and large chain. The small chain promotes the hydrolysis of glutamine to ammonia, which is used by the large chain to synthesise carbamoyl phosphate. The small chain has a GATase domain in the carboxyl terminus.
This entry represents the N-terminal domain of the small subunit of carbamoyl phosphate synthase. Structurally, it forms a 3-layer beta/beta/alpha fold of a type that is thought to be mobile in most proteins that carry it [ (PUBMED:10587438) (PUBMED:11729189) ].
Family alignment:
There are 25477 CPSase_sm_chain domains in 25475 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing CPSase_sm_chain domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with CPSase_sm_chain domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing CPSase_sm_chain domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
Mammalian carbamyl phosphate synthetase (CPS). DNA sequence and evolutionof the CPS domain of the Syrian hamster multifunctional protein CAD.
J Biol Chem. 1990; 265: 10395-402
Display abstract
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.
