Q26997 · HGXR_TOXGO
- ProteinHypoxanthine-guanine-xanthine phosphoribosyltransferase
- GeneHPRT
- StatusUniProtKB reviewed (Swiss-Prot)
- Organism
- Amino acids230 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
Catalyzes the transfer of a ribosyl phosphate group from 5-phosphoribose 1-diphosphate to the N9 of hypoxanthine, guanine or xanthine, leading to IMP, GMP and XMP, respectively. Plays a central role in the generation of purine nucleotides through the purine salvage pathway.
Catalytic activity
- diphosphate + IMP = 5-phospho-alpha-D-ribose 1-diphosphate + hypoxanthineThis reaction proceeds in the backward direction.
Cofactor
Note: Binds 2 magnesium ions per subunit. The magnesium ions are essentially bound to the substrate and have few direct interactions with the protein.
Pathway
Purine metabolism; GMP biosynthesis via salvage pathway; GMP from guanine: step 1/1.
Purine metabolism; IMP biosynthesis via salvage pathway; IMP from hypoxanthine: step 1/1.
Purine metabolism; XMP biosynthesis via salvage pathway; XMP from xanthine: step 1/1.
Features
Showing features for binding site, active site.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Binding site | 79 | GMP (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 146-154 | GMP (UniProtKB | ChEBI) | ||||
Sequence: EDIVDTGFT | ||||||
Active site | 150 | Proton acceptor | ||||
Sequence: D | ||||||
Binding site | 178 | GMP (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 199-200 | GMP (UniProtKB | ChEBI) | ||||
Sequence: WI | ||||||
Binding site | 206 | GMP (UniProtKB | ChEBI) | ||||
Sequence: D | ||||||
Binding site | 206 | Mg2+ (UniProtKB | ChEBI) | ||||
Sequence: D |
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | cytoplasm | |
Molecular Function | guanine phosphoribosyltransferase activity | |
Molecular Function | hypoxanthine phosphoribosyltransferase activity | |
Molecular Function | metal ion binding | |
Molecular Function | nucleotide binding | |
Molecular Function | xanthine phosphoribosyltransferase activity | |
Biological Process | GMP salvage | |
Biological Process | IMP salvage | |
Biological Process | purine ribonucleoside salvage | |
Biological Process | XMP salvage |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameHypoxanthine-guanine-xanthine phosphoribosyltransferase
- EC number
- Short namesHGPRT; HGXPRT; HGXPRTase
Gene names
Organism names
- Organism
- Strain
- Taxonomic lineageEukaryota > Sar > Alveolata > Apicomplexa > Conoidasida > Coccidia > Eucoccidiorida > Eimeriorina > Sarcocystidae > Toxoplasma
Accessions
- Primary accessionQ26997
Organism-specific databases
Subcellular Location
Phenotypes & Variants
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 150 | Strongly reduced catalytic activity. | ||||
Sequence: D → A |
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000139599 | 1-230 | Hypoxanthine-guanine-xanthine phosphoribosyltransferase | |||
Sequence: MASKPIEDYGKGKGRIEPMYIPDNTFYNADDFLVPPHCKPYIDKILLPGGLVKDRVEKLAYDIHRTYFGEELHIICILKGSRGFFNLLIDYLATIQKYSGRESSVPPFFEHYVRLKSYQNDNSTGQLTVLSDDLSIFRDKHVLIVEDIVDTGFTLTEFGERLKAVGPKSMRIATLVEKRTDRSNSLKGDFVGFSIEDVWIVGCCYDFNEMFRDFDHVAVLSDAARKKFEK |
Interaction
Subunit
Homodimer at low ionic strength and homotetramer at high ionic strength.
Structure
Sequence
- Sequence statusComplete
- Length230
- Mass (Da)26,386
- Last updated1996-11-01 v1
- ChecksumC3784254EF96361D
Keywords
- Technical term