Inosine triphosphate pyrophosphatase is an enzyme that in humans is encoded by the ITPA gene,[5][6] by the rdgB gene in bacteria E.coli[7] and the HAM1 gene in yeast S. cerevisiae;[8] the protein is also encoded by some RNA viruses of the Potyviridae family.[9] Two transcript variants encoding two different isoforms have been found for this gene. Also, at least two other transcript variants have been identified which are probably regulatory rather than protein-coding.[citation needed]

ITPA
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesITPA, C20orf37, HLC14-06-P, dJ794I6.3, My049, ITPase, NTPase, inosine triphosphatase, DEE35
External IDsOMIM: 147520; MGI: 96622; HomoloGene: 6289; GeneCards: ITPA; OMA:ITPA - orthologs
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_025922
NM_001362648

RefSeq (protein)

NP_080198
NP_001349577

Location (UCSC)Chr 20: 3.21 – 3.22 MbChr 2: 130.51 – 130.52 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Function

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The protein encoded by this gene hydrolyzes inosine triphosphate and deoxyinosine triphosphate to the monophosphate nucleotide and diphosphate.[6] The enzyme possesses a multiple substrate-specificity and acts on other nucleotides including xanthosine triphosphate and deoxyxanthosine triphosphate.[8] The encoded protein, which is a member of the HAM1 NTPase protein family, is found in the cytoplasm and acts as a homodimer.

Clinical significance

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Defects in the encoded protein can result in inosine triphosphate pyrophosphorylase deficiency.[6] The enzyme ITPase dephosphorylates ribavirin triphosphate in vitro to ribavirin monophosphate, and ITPase reduced enzymatic activity present in 30 % of humans potentiates mutagenesis in hepatitis C virus.[10] Gene variants predicting reduced predicted ITPase activity have been associated with decreased risk of ribavirin-induced anemia, increased risk of thrombocytopenia, lower ribavirin concentrations, as well as a ribavirin-like reduced relapse risk following interferon-based therapy for hepatitis C virus (HCV) genotype 2 or 3 infection. [11]

Reading

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References

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  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000125877Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000074797Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ Lin S, McLennan AG, Ying K, Wang Z, Gu S, Jin H, et al. (May 2001). "Cloning, expression, and characterization of a human inosine triphosphate pyrophosphatase encoded by the itpa gene". J Biol Chem. 276 (22): 18695–701. doi:10.1074/jbc.M011084200. PMID 11278832.
  6. ^ a b c "Entrez Gene: ITPA inosine triphosphatase (nucleoside triphosphate pyrophosphatase)".
  7. ^ Burgis NE, Cunningham RP (2007). "Substrate specificity of RdgB protein, a deoxyribonucleoside triphosphate pyrophosphohydrolase". J Biol Chem. 282 (8): 3531–8. doi:10.1074/jbc.M608708200. PMID 17090528.
  8. ^ a b Davies O, Mendes P, Smallbone K, Malys N (2012). "Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism". BMB Reports. 45 (4): 259–64. doi:10.5483/BMBRep.2012.45.4.259. PMID 22531138.
  9. ^ Pasin F, Daròs JA, Tzanetakis IE (2022). "Proteome expansion in the Potyviridae evolutionary radiation". FEMS Microbiology Reviews. 46 (4): fuac011. doi:10.1093/femsre/fuac011. ISSN 1574-6976. PMC 9249622. PMID 35195244.
  10. ^ Nyström K, Wanrooij PH, Waldenström J, Adamek L, Brunet S, Said J, et al. (October 2018). "Inosine Triphosphate Pyrophosphatase Dephosphorylates Ribavirin Triphosphate and Reduced Enzymatic Activity Potentiates Mutagenesis in Hepatitis C Virus". Journal of Virology. 92 (19): 01087–18. doi:10.1002/hep.27009. PMC 6146798. PMID 30045981.
  11. ^ Rembeck K, Waldenstrom J, Hellstrand K, Nilsson S, Nyström K, Martner A, et al. (June 2014). "Variants of the inosine triphosphate pyrophosphatase gene are associated with reduced relapse risk following treatment for HCV genotype 2/3". Hepatology. 59 (6): 2131–2139. doi:10.1002/hep.27009. PMID 24519039.