Phosphoribosylaminoimidazole carboxylase
| phosphoribosylaminoimidazole carboxylase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 4.1.1.21 | ||||||||
| CAS number | Template:CAS | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
|
|||||||||
| phosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase | |
|---|---|
| Identifiers | |
| Symbol | PAICS |
| Alt. symbols | PAIS |
| Entrez | 10606 |
| HUGO | 8587 |
| OMIM | 172439 |
| RefSeq | NM_006452 |
| UniProt | P22234 |
| Other data | |
| EC number | 4.1.1.21 |
| Locus | Chr. 4 pter-q21 |
Phosphoribosylaminoimidazole carboxylase (or AIR carboxylase) is an enzyme involved in nucleotide biosynthesis and in particular in purine biosynthesis. It catalyzes the conversion of 5'-phosphoribosyl-5-aminoimidazole ("AIR") into 5'-phosphoribosyl-4-carboxy-5-aminoimidazole ("CAIR") as described in the reaction:
- 5-aminoimidazole ribonucleotide + CO2
5'-phosphoribosyl-4-carboxy-5-aminoimidazole + 2 H+
In plants and fungi
Phosphoribosylaminoimidazole carboxylase is a fusion protein in plants and fungi, but consists of two non-interacting proteins in bacteria, PurK and PurE.
The crystal structure of PurE indicates a unique quaternary structure that confirms the octameric nature of the enzyme.[1]
In Escherichia coli
In the bacterium Escherichia coli the reaction is catalyzed in two steps carried out by two separate enzymes, PurK and PurE.
PurK, N5-carboxyaminoimidazole ribonucleotide synthetase, catalyzes the conversion of 5-aminoimidazole ribonucleotide ("AIR"), ATP, and bicarbonate to N5-carboxyaminoimidazole ribonucleotide ("N5-CAIR"), ADP, and Pi.
PurE, N5-carboxyaminoimidazole ribonucleotide mutase, converts N5-CAIR to CAIR, the sixth step of de novo purine biosynthesis. In the presence of high concentrations of bicarbonate, PurE is reported able to convert AIR to CAIR directly and without ATP. Some members of this family contain two copies of this domain.[2]
References
External links
- phosphoribosylaminoimidazole carboxylase at the US National Library of Medicine Medical Subject Headings (MeSH)
- PAICS photo
This article incorporates text from the public domain Pfam and InterPro IPR000031
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