Structure of PDB 1qk3 Chain C

Receptor sequence

>1qk3C (length=213) Species: 383379 (Toxoplasma gondii RH)

GSHMASKPIEDYGKGKGRIEPMYIPDNTFYNADDFLVPPHCKPYIDKILL
PGGLVKDRVEKLAYDIHRTYFGEELHIICILKGSRGFFNLLIDYLATIQK
YSGRESSVPPFFEHYVRLDLSIFRDKHVLIVEDIVDTGFTLTEFGERLKA
VGPKSMRIATLVEKRTDRSLKGDFVGFSIEDVWIVGCCYDFNEMFRDFDH
VAVLSDAARKKFE

3D structure

• PDB: 1qk3 Crystal Structures of the Toxoplasma Gondii Hypoxanthine-Guanine Phosphoribosyltransferase Gmp and -Imp Complexes: Comparison of Purine Binding Interactions with the Xmp Complex
• Chain: C
• Resolution: 1.65 Å

Enzymatic activity

• Catalytic site (original residue number in PDB): E146 D147 D150 W199 R212
• Catalytic site (residue number reindexed from 1): E132 D133 D136 W183 R196
• Enzyme Commision number: 2.4.2.22: xanthine phosphoribosyltransferase.
  2.4.2.8: hypoxanthine phosphoribosyltransferase.

Interaction with ligand

Site #	Ligand	Ligand chain	Binding residues on receptor (original residue number in PDB)	Binding residues on receptor (residue number reindexed from 1)	Binding affinity
BS01	5GP	C	E146 D147 I148 D150 T151 G152 T154 K178 W199 I200	E132 D133 I134 D136 T137 G138 T140 K164 W183 I184	MOAD: Kd=7.1uM

Gene Ontology

Molecular Function

• GO:0000166 nucleotide binding
• GO:0000287 magnesium ion binding
• GO:0000310 xanthine phosphoribosyltransferase activity
• GO:0004422 hypoxanthine phosphoribosyltransferase activity
• GO:0016757 glycosyltransferase activity
• GO:0046872 metal ion binding
• GO:0052657 guanine phosphoribosyltransferase activity

Biological Process

• GO:0006166 purine ribonucleoside salvage
• GO:0006178 guanine salvage
• GO:0032263 GMP salvage
• GO:0032264 IMP salvage
• GO:0032265 XMP salvage
• GO:0046100 hypoxanthine metabolic process

Cellular Component

• GO:0005737 cytoplasm
• GO:0005829 cytosol

External links

• PDB: RCSB:1qk3, PDBe:1qk3, PDBj:1qk3
• PDBsum: 1qk3
• PubMed: 10545170
• UniProt: Q26997|HGXR_TOXGO Hypoxanthine-guanine-xanthine phosphoribosyltransferase (Gene Name=HPRT)