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Q26997 (HGXR_TOXGO) Reviewed, UniProtKB/Swiss-Prot

Last modified June 11, 2014. Version 80. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (3) | Third-party data text xml rdf/xml gff fasta
to top of pageNames·Attributes·General annotation·Ontologies·Sequence annotation·Sequences·References·Cross-refs·Entry info·DocumentsCustomize order

Names and origin

Protein namesRecommended name:
Hypoxanthine-guanine-xanthine phosphoribosyltransferase

Short name=HGPRT
Short name=HGXPRT
Short name=HGXPRTase
EC=2.4.2.-
Gene names
Name:HPRT
OrganismToxoplasma gondii
Taxonomic identifier5811 [NCBI]
Taxonomic lineageEukaryotaAlveolataApicomplexaConoidasidaCoccidiaEucoccidioridaEimeriorinaSarcocystidaeToxoplasma

Protein attributes

Sequence length230 AA.
Sequence statusComplete.
Protein existenceEvidence at protein level

General annotation (Comments)

Function

Catalyzes the transfer of a ribosyl phosphate group from 5-phosphoribose 1-diphosphate to the N9 of hypoxanthine, guanine or xanthine. Ref.5

Catalytic activity

IMP + diphosphate = hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate. Ref.4 Ref.5

GMP + diphosphate = guanine + 5-phospho-alpha-D-ribose 1-diphosphate. Ref.4 Ref.5

5-phospho-alpha-D-ribose 1-diphosphate + xanthine = (9-D-ribosylxanthine)-5'-phosphate + phosphate. Ref.4 Ref.5

Cofactor

Binds 2 magnesium ions per subunit. The magnesium ions are essentially bound to the substrate and have few direct interactions with the protein. Ref.4

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.

Subunit structure

Homodimer at low ionic strength and homotetramer at high ionic strength. Ref.4

Subcellular location

Cytoplasm.

Sequence similarities

Belongs to the purine/pyrimidine phosphoribosyltransferase family.

Ontologies

Keywords
   Biological processPurine salvage
   Cellular componentCytoplasm
   LigandMagnesium
Metal-binding
Nucleotide-binding
   Molecular functionGlycosyltransferase
Transferase
   Technical term3D-structure
Gene Ontology (GO)
   Biological_processGMP salvage

Inferred from electronic annotation. Source: UniProtKB-UniPathway

IMP salvage

Inferred from electronic annotation. Source: UniProtKB-UniPathway

XMP salvage

Inferred from electronic annotation. Source: UniProtKB-UniPathway

purine ribonucleoside salvage

Inferred from electronic annotation. Source: UniProtKB-KW

   Cellular_componentcytoplasm

Inferred from electronic annotation. Source: UniProtKB-SubCell

   Molecular_functionhypoxanthine phosphoribosyltransferase activity

Inferred from electronic annotation. Source: InterPro

metal ion binding

Inferred from electronic annotation. Source: UniProtKB-KW

nucleotide binding

Inferred from electronic annotation. Source: UniProtKB-KW

Complete GO annotation...

Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifier

Molecule processing

Chain1 – 230230Hypoxanthine-guanine-xanthine phosphoribosyltransferase
PRO_0000139599

Regions

Nucleotide binding146 – 1549GMP
Nucleotide binding199 – 2002GMP

Sites

Active site1501Proton acceptor Ref.4 Ref.5
Metal binding2061Magnesium
Binding site791GMP
Binding site1781GMP
Binding site2061GMP; via carbonyl oxygen

Experimental info

Mutagenesis1501D → A: Strongly reduced catalytic activity. Ref.4

Secondary structure

..................................... 230
Helix Strand Turn

Details...

Sequences

Sequence LengthMass (Da)Tools
Q26997 [UniParc].

Last modified November 1, 1996. Version 1.
Checksum: C3784254EF96361D

FASTA23026,386
        10         20         30         40         50         60 
MASKPIEDYG KGKGRIEPMY IPDNTFYNAD DFLVPPHCKP YIDKILLPGG LVKDRVEKLA 

        70         80         90        100        110        120 
YDIHRTYFGE ELHIICILKG SRGFFNLLID YLATIQKYSG RESSVPPFFE HYVRLKSYQN 

       130        140        150        160        170        180 
DNSTGQLTVL SDDLSIFRDK HVLIVEDIVD TGFTLTEFGE RLKAVGPKSM RIATLVEKRT 

       190        200        210        220        230 
DRSNSLKGDF VGFSIEDVWI VGCCYDFNEM FRDFDHVAVL SDAARKKFEK 

« Hide

References

[1]"Isolation and sequencing of a cDNA encoding the hypoxanthine-guanine phosphoribosyltransferase from Toxoplasma gondii."
Vasanthakumar G., van Ginkel S., Parish G.
Gene 147:153-154(1994) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA].
Strain: RH.
[2]"Crystal structures of Toxoplasma gondii HGXPRTase reveal the catalytic role of a long flexible loop."
Schumacher M.A., Carter D., Roos D.S., Ullman B., Brennan R.G.
Nat. Struct. Biol. 3:881-887(1996) [PubMed] [Europe PMC] [Abstract]
Cited for: X-RAY CRYSTALLOGRAPHY (2.4 ANGSTROMS).
[3]"Crystal structures of the Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase-GMP and -IMP complexes: comparison of purine binding interactions with the XMP complex."
Heroux A., White E.L., Ross L.J., Borhani D.W.
Biochemistry 38:14485-14494(1999) [PubMed] [Europe PMC] [Abstract]
Cited for: X-RAY CRYSTALLOGRAPHY (1.65 ANGSTROMS).
[4]"Crystal structure of Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase with bound XMP, pyrophosphate and two Mg2+ ions: insights into the catalytic mechanism."
Heroux A., White E.L., Ross L.J., Davis R.L., Borhani D.W.
Biochemistry 38:14495-14506(1999) [PubMed] [Europe PMC] [Abstract]
Cited for: X-RAY CRYSTALLOGRAPHY (1.6 ANGSTROMS) OF MUTANT ALA-150 IN COMPLEX WITH XMP; PYROPHOSPHATE AND MAGNESIUM IONS, COFACTOR, CATALYTIC ACTIVITY, SUBUNIT, ACTIVE SITE, MUTAGENESIS OF ASP-150.
[5]"Substrate deformation in a hypoxanthine-guanine phosphoribosyltransferase ternary complex: the structural basis for catalysis."
Heroux A., White E.L., Ross L.J., Kuzin A.P., Borhani D.W.
Structure 8:1309-1318(2000) [PubMed] [Europe PMC] [Abstract]
Cited for: X-RAY CRYSTALLOGRAPHY (1.05 ANGSTROMS) IN COMPLEX WITH MAGNESIUM; PHOSPHORIBOSYLPYROPHOSPHATE AND 9-DEAZAGUANINE, CATALYTIC ACTIVITY, ACTIVE SITE, FUNCTION.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ
U09219 mRNA. Translation: AAA57068.1.

3D structure databases

PDBe
RCSB-PDB
PDBj
EntryMethodResolution (Å)ChainPositionsPDBsum
1DBRX-ray2.40A/B/C/D1-230[»]
1FSGX-ray1.05A/C1-230[»]
1QK3X-ray1.65A/B/C/D1-230[»]
1QK4X-ray1.90A/B/C/D1-230[»]
1QK5X-ray1.60A/B1-230[»]
ProteinModelPortalQ26997.
SMRQ26997. Positions 1-230.
ModBaseSearch...
MobiDBSearch...

Protocols and materials databases

StructuralBiologyKnowledgebaseSearch...

Enzyme and pathway databases

UniPathwayUPA00591; UER00648.
UPA00602; UER00658.
UPA00909; UER00887.

Family and domain databases

Gene3D3.40.50.2020. 1 hit.
InterProIPR005904. Hxn_phspho_trans.
IPR000836. PRibTrfase_dom.
IPR029057. PRTase-like.
[Graphical view]
PfamPF00156. Pribosyltran. 1 hit.
[Graphical view]
SUPFAMSSF53271. SSF53271. 1 hit.
TIGRFAMsTIGR01203. HGPRTase. 1 hit.
PROSITEPS00103. PUR_PYR_PR_TRANSFER. 1 hit.
[Graphical view]
ProtoNetSearch...

Other

EvolutionaryTraceQ26997.

Entry information

Entry nameHGXR_TOXGO
AccessionPrimary (citable) accession number: Q26997
Entry history
Integrated into UniProtKB/Swiss-Prot: November 1, 1997
Last sequence update: November 1, 1996
Last modified: June 11, 2014
This is version 80 of the entry and version 1 of the sequence. [Complete history]
Entry statusReviewed (UniProtKB/Swiss-Prot)

Relevant documents

SIMILARITY comments

Index of protein domains and families

PDB cross-references

Index of Protein Data Bank (PDB) cross-references

PATHWAY comments

Index of metabolic and biosynthesis pathways