GO:0047429 nucleoside triphosphate diphosphatase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047429 nucleoside triphosphate diphosphatase activity catalyzes the hydrolysis of a nucleoside triphosphate to a nucleotide and diphosphate.
• The best-characterized enzyme carrying this activity is inosine triphosphate pyrophosphatase (ITPA), which removes noncanonical inosine triphosphate from nucleotide pools.
• Reduced ITPA activity causes accumulation of ITP, which can be incorporated into RNA and alter cellular physiology.
• ITPA activity predicts methotrexate remission in juvenile idiopathic arthritis and ribavirin-induced anemia in hepatitis C patients.
• ITPA polymorphisms influence thiopurine and azathioprine toxicity in inflammatory bowel disease and systemic lupus erythematosus.
• CRISPR knockout, point-mutation, knock-in and overexpression models enable causal testing of GO:0047429-related genes.
Description
GO:0047429 nucleoside triphosphate diphosphatase activity is a molecular function defined as the catalysis of the reaction: a nucleoside triphosphate + H2O = a nucleotide + H+ + diphosphate. This activity is essential for maintaining nucleotide pool fidelity because it removes noncanonical or excess nucleoside triphosphates that would otherwise be incorporated into nucleic acids. The prototype enzyme for this GO term is inosine triphosphate pyrophosphatase (ITPA), which hydrolyzes inosine triphosphate (ITP) to inosine monophosphate (IMP) and diphosphate. Researchers study GO:0047429 because its dysfunction is linked to drug toxicity and disease. For example, ITPA activity predicts methotrexate remission in juvenile idiopathic arthritis, and reduced ITPA activity potentiates ribavirin mutagenesis in hepatitis C virus. ITPA polymorphisms also affect thiopurine metabolism in inflammatory bowel disease and azathioprine toxicity in systemic lupus erythematosus. Understanding GO:0047429 requires integrating biochemical assays, genetic models and clinical pharmacogenetics. This article summarizes the definition, mechanism, key genes, disease links and CRISPR-based research methods for this activity, based on QuickGO and verified PubMed literature.
nucleoside triphosphate diphosphatase activity At A Glance
| GO ID | GO:0047429 |
|---|---|
| GO term | nucleoside triphosphate diphosphatase activity |
| Ontology | molecular_function |
| Definition | Catalysis of the reaction: a nucleoside triphosphate + H2O = a nucleotide + H+ + diphosphate |
| Synonym | nucleoside-triphosphate diphosphatase activity; nucleoside-triphosphate diphosphohydrolase activity; nucleoside-triphosphate pyrophosphatase activity |
| Major function | Hydrolysis of noncanonical nucleoside triphosphates to maintain nucleotide pool fidelity |
| Representative enzyme | Inosine triphosphate pyrophosphatase (ITPA) |
| Substrate example | Inosine triphosphate (ITP) |
| Product example | Inosine monophosphate (IMP) and diphosphate |
What Is GO:0047429?
GO:0047429 nucleoside triphosphate diphosphatase activity is a molecular function that catalyzes the hydrolysis of a nucleoside triphosphate, producing a nucleotide, a proton and diphosphate. In practical terms, it is a proofreading or sanitizing activity that removes abnormal or excess triphosphate nucleotides from the cell. The reaction consumes water and releases energy as diphosphate, and it is distinct from kinases or ATPases because the product is a nucleotide (not a nucleoside diphosphate) and diphosphate.
Why Is nucleoside triphosphate diphosphatase activity Important in Cell Biology?
GO:0047429 is important because it safeguards nucleotide pools and prevents incorporation of noncanonical nucleotides into RNA and DNA. Loss of this activity leads to accumulation of ITP, which can be misincorporated and cause mutagenesis or cellular stress. Clinically, ITPA activity predicts drug responses and toxicities, including methotrexate remission in juvenile idiopathic arthritis, ribavirin-induced anemia in hepatitis C, and thiopurine toxicity in inflammatory bowel disease. Therefore, GO:0047429 is a key node linking nucleotide metabolism, pharmacogenetics and human disease.
• Maintains nucleotide pool fidelity by removing noncanonical triphosphates such as ITP.
• Prevents incorporation of inosine into RNA, which can alter translation and cellular function.
• Predicts methotrexate remission in juvenile idiopathic arthritis.
• Modulates ribavirin mutagenesis in hepatitis C virus.
• Predicts ribavirin-induced anemia in hepatitis C patients.
• Influences thiopurine metabolism and toxicity in inflammatory bowel disease.
• Affects azathioprine toxicity in systemic lupus erythematosus.
• Provides a target for biochemical engineering of improved substrate selectivity.
• Serves as a model for studying enzyme evolution and substrate specificity.
• Enables pharmacogenetic testing to personalize drug dosing.
Molecular Mechanism of nucleoside triphosphate diphosphatase activity
Substrate recognition and binding
In simple terms: The enzyme grabs an abnormal nucleotide triphosphate and holds it in place.
ITPA, the prototype enzyme for GO:0047429, binds inosine triphosphate (ITP) with high specificity, positioning the substrate for hydrolysis. Structural and biochemical studies show that the enzyme discriminates against canonical nucleotides such as ATP and GTP, ensuring that only noncanonical triphosphates are removed.
Catalytic hydrolysis
In simple terms: Water is used to split the triphosphate into a nucleotide and diphosphate.
The catalytic mechanism involves nucleophilic attack by water on the terminal phosphate, releasing diphosphate and leaving a nucleotide monophosphate. This reaction is dependent on divalent metal ions, typically magnesium, which stabilize the transition state.
Product release and pool sanitation
In simple terms: The harmless product is released, and the cell avoids using the wrong building block.
After hydrolysis, IMP and diphosphate are released, and the enzyme resets for another cycle. This sanitation function prevents ITP from being incorporated into RNA, which would otherwise cause mutagenesis or translational errors.
Regulation by substrate availability and enzyme levels
In simple terms: The enzyme works faster when there is more abnormal nucleotide around.
ITPA activity is influenced by substrate concentration and enzyme expression levels. Genetic variants such as ITPA 94C>A reduce enzymatic activity, leading to ITP accumulation and altered drug responses.
Substrate selectivity and engineering
In simple terms: Scientists can tweak the enzyme to prefer certain substrates.
Directed evolution and biochemical studies have generated ITPA variants with improved substrate selectivity, providing insights into the determinants of GO:0047429 activity. These studies help explain how mutations affect enzyme function and drug metabolism.
Key Genes Involved in GO:0047429 nucleoside triphosphate diphosphatase activity
The following genes and proteins are directly associated with GO:0047429 nucleoside triphosphate diphosphatase activity, based on verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ITPA | Encodes inosine triphosphate pyrophosphatase, the prototype enzyme for GO:0047429 | Central to nucleotide pool sanitation and pharmacogenetics |
| ITPA (94C>A variant) | Reduces ITPA enzymatic activity | Predicts ribavirin-induced anemia and thiopurine toxicity |
| ITPA (wild-type) | Hydrolyzes ITP to IMP and diphosphate | Model for substrate specificity studies |
| ITPA (engineered variants) | Improved substrate selectivity | Biochemical and structural studies |
| HPRT1 | Purine salvage pathway enzyme | Context for nucleotide pool metabolism |
| IMPDH1 | Inosine monophosphate dehydrogenase | Links ITP metabolism to guanine nucleotide synthesis |
| IMPDH2 | Inosine monophosphate dehydrogenase 2 | Drug target in immunosuppression and cancer |
| NT5C2 | Cytosolic 5'-nucleotidase | Nucleotide pool regulation |
| NT5C3A | Pyrimidine 5'-nucleotidase | Nucleotide catabolism |
| ADA | Adenosine deaminase | Purine metabolism and immunodeficiency |
| PNP | Purine nucleoside phosphorylase | Purine salvage and immunodeficiency |
| GART | Phosphoribosylglycinamide formyltransferase | De novo purine synthesis |
| ATIC | AICAR transformylase/IMP cyclohydrolase | De novo purine synthesis |
| MTHFR | Methylenetetrahydrofolate reductase | Folate metabolism and methotrexate response |
| TYMS | Thymidylate synthase | Methotrexate and fluoropyrimidine response |
| SLC29A1 | Equilibrative nucleoside transporter 1 | Ribavirin uptake and response |
| SLC28A2 | Concentrative nucleoside transporter 2 | Nucleoside drug transport |
| GART | Glycinamide ribonucleotide transformylase | Purine synthesis and drug targeting |
How Is nucleoside triphosphate diphosphatase activity Regulated?
GO:0047429 activity is regulated at multiple levels. Substrate availability directly controls enzyme flux, as ITPA hydrolyzes ITP when it accumulates. Genetic regulation occurs through polymorphisms such as ITPA 94C>A, which reduces enzymatic activity and alters drug metabolism. Additionally, enzyme expression levels can be modulated by cellular stress and nucleotide demand, although specific transcriptional regulators are not fully defined in the verified literature. Biochemical studies show that engineered ITPA variants can alter substrate selectivity, indicating that the active site is tunable.
nucleoside triphosphate diphosphatase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ITPA | Juvenile idiopathic arthritis (methotrexate response) | ITPA knockout or point-mutation cell lines |
| ITPA | Hepatitis C (ribavirin-induced anemia) | ITPA overexpression and knockout hepatocyte models |
| ITPA | Inflammatory bowel disease (thiopurine toxicity) | ITPA 94C>A knock-in intestinal epithelial cells |
| ITPA | Systemic lupus erythematosus (azathioprine toxicity) | ITPA knockout immune cells |
| ITPA | Nucleotide pool imbalance | ITPA knockout cell lines with ITP accumulation |
Juvenile idiopathic arthritis and methotrexate response
ITPA activity predicts methotrexate remission in juvenile idiopathic arthritis, suggesting that GO:0047429 function influences treatment outcomes. Patients with lower ITPA activity may have altered methotrexate metabolism and response.
Hepatitis C and ribavirin-induced anemia
Reduced ITPA activity predicts ribavirin-induced anemia in hepatitis C patients more accurately than ITPA genotype alone. ITPA dephosphorylates ribavirin triphosphate, and reduced activity potentiates mutagenesis in hepatitis C virus.
Inflammatory bowel disease and thiopurine toxicity
ITPA polymorphisms influence thiopurine metabolism and toxicity in inflammatory bowel disease, linking GO:0047429 to drug safety. Pharmacogenetic testing of ITPA can guide thiopurine dosing.
Systemic lupus erythematosus and azathioprine toxicity
The ITPA 94C>A polymorphism has clinical implications for patients with systemic lupus erythematosus treated with azathioprine, affecting toxicity risk. This highlights the role of GO:0047429 in autoimmune disease management.
From nucleoside triphosphate diphosphatase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does ITPA loss cause ITP accumulation? | ITPA knockout cell line |
| Does ITPA 94C>A reduce enzymatic activity? | Point-mutation knock-in cell line |
| Can engineered ITPA improve substrate selectivity? | Knock-in of engineered ITPA variants |
| Does ITPA overexpression protect against ribavirin toxicity? | ITPA overexpression cell line |
| Does ITPA activity predict methotrexate response? | Patient-derived cells with ITPA genotyping |
| Can ITPA be tagged for localization studies? | Tagged knock-in cell line |
How to Study the nucleoside triphosphate diphosphatase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzyme activity assay | Hydrolysis of ITP to IMP | Quantify ITPA kinetics |
| Genotyping | ITPA 94C>A polymorphism | Predict drug toxicity |
| CRISPR knockout | Loss of ITPA function | Test causal role in drug response |
| CRISPR point mutation | Specific ITPA variant effects | Model pharmacogenetic variants |
| CRISPR knock-in | Engineered ITPA variants | Study substrate selectivity |
| Overexpression | Increased ITPA levels | Test protection against ribavirin |
| Mass spectrometry | Nucleotide pool composition | Measure ITP accumulation |
| RNA sequencing | Transcriptional changes | Assess cellular response to ITP |
Biochemical enzyme assays
ITPA activity can be measured using spectrophotometric or chromatographic assays that detect the hydrolysis of ITP to IMP and diphosphate. These assays are used to quantify enzyme kinetics and substrate specificity.
Genotyping and pharmacogenetics
ITPA polymorphisms such as 94C>A are genotyped to predict drug toxicity and response. Clinical studies use genotyping to correlate ITPA activity with outcomes.
CRISPR-based genetic models
CRISPR knockout, point-mutation and knock-in models enable causal testing of ITPA variants in isogenic cell lines. These models help dissect the role of GO:0047429 in drug metabolism.
Nucleotide pool analysis
Mass spectrometry-based methods quantify ITP and other nucleotides to assess the impact of ITPA activity on pool composition. This is critical for linking GO:0047429 to cellular phenotypes.
How CRISPR Can Be Used to Study GO:0047429 nucleoside triphosphate diphosphatase activity
Knockout
CRISPR knockout of ITPA eliminates GO:0047429 activity, causing ITP accumulation and sensitizing cells to nucleotide analogs. These models are used to study drug toxicity and nucleotide pool imbalance.
Point Mutation
CRISPR point mutation introduces ITPA 94C>A or other variants to model reduced enzymatic activity. These isogenic models help dissect the effect of specific polymorphisms on drug response.
Knock-in
CRISPR knock-in of engineered ITPA variants allows testing of substrate selectivity and catalytic efficiency. Tagged knock-in enables localization and interaction studies.
Overexpression
CRISPR overexpression of ITPA increases GO:0047429 activity, which can protect cells from ribavirin-induced toxicity. Overexpression models are useful for testing dose-dependent effects.
How EDITGENE Supports nucleoside triphosphate diphosphatase activity Research
Researchers studying nucleoside triphosphate diphosphatase activity-related genes often need to determine whether a candidate gene is causally involved in drug response, nucleotide pool regulation or disease. EDITGENE provides CRISPR-based cell model services to enable such causal studies.
Contact EDITGENE today to design your custom CRISPR model for nucleoside triphosphate diphosphatase activity research.
Frequently Asked Questions About nucleoside triphosphate diphosphatase activity
What is nucleoside triphosphate diphosphatase activity?
It is a molecular function (GO:0047429) that catalyzes the hydrolysis of a nucleoside triphosphate to a nucleotide and diphosphate.
What genes are involved in nucleoside triphosphate diphosphatase activity?
The best-characterized gene is ITPA, which encodes inosine triphosphate pyrophosphatase.
What is the role of ITPA in nucleotide metabolism?
ITPA removes noncanonical ITP from nucleotide pools, preventing its incorporation into RNA.
How is ITPA activity measured?
ITPA activity is measured by biochemical assays that detect the hydrolysis of ITP to IMP and diphosphate.
What diseases are linked to ITPA mutations?
ITPA mutations are linked to methotrexate response in juvenile idiopathic arthritis, ribavirin-induced anemia in hepatitis C, and thiopurine toxicity in inflammatory bowel disease.
What is the ITPA 94C>A polymorphism?
It is a common variant that reduces ITPA enzymatic activity and affects drug metabolism.
Can CRISPR be used to study nucleoside triphosphate diphosphatase activity?
Yes, CRISPR knockout, point mutation, knock-in and overexpression models enable causal studies of ITPA function.
Why is ITPA important for ribavirin treatment?
ITPA dephosphorylates ribavirin triphosphate, and reduced activity potentiates ribavirin mutagenesis in hepatitis C virus.
What is the substrate of ITPA?
The primary substrate is inosine triphosphate (ITP), which is hydrolyzed to IMP and diphosphate.
How does ITPA activity predict drug response?
ITPA activity predicts methotrexate remission in juvenile idiopathic arthritis and ribavirin-induced anemia in hepatitis C patients.
Conclusion
GO:0047429 nucleoside triphosphate diphosphatase activity is a critical molecular function that maintains nucleotide pool fidelity and influences drug responses. ITPA is the prototype enzyme, and its genetic variants are linked to methotrexate, ribavirin and thiopurine outcomes. Understanding this activity requires integrated biochemical, genetic and clinical approaches. CRISPR-based cell models provide a powerful way to test causality and dissect mechanisms of GO:0047429 in human disease. EDITGENE offers comprehensive services to support such research.
References
- 1. Sindici Forgiarini S et al.. 2026. Inosine-Triphosphate-Pyrophosphatase Activity as a Potential Predictor of Methotrexate Remission in Juvenile Idiopathic Arthritis.. Arthritis Rheumatol 78(9):1989-1999 PMID: 41735770
- 2. Nyström K et al.. 2018. Inosine Triphosphate Pyrophosphatase Dephosphorylates Ribavirin Triphosphate and Reduced Enzymatic Activity Potentiates Mutagenesis in Hepatitis C Virus.. J Virol 92(19) PMID: 30045981
- 3. Burgis NE et al.. 2024. An ITPA Enzyme with Improved Substrate Selectivity.. Protein J 43(1):62-71 PMID: 38066288
- 4. Derijks LJ et al.. 2010. Pharmacogenetics of thiopurines in inflammatory bowel disease.. Curr Pharm Des 16(2):145-54 PMID: 20205660
- 5. Simone PD et al.. 2013. ITPA (inosine triphosphate pyrophosphatase): from surveillance of nucleotide pools to human disease and pharmacogenetics.. Mutat Res 753(2):131-146 PMID: 23969025
- 6. Burgis NE. 2016. A disease spectrum for ITPA variation: advances in biochemical and clinical research.. J Biomed Sci 23(1):73 PMID: 27770805
- 7. Peltenburg NC et al.. 2015. Inosine triphosphate pyrophosphohydrolase activity: more accurate predictor for ribavirin-induced anemia in hepatitis C infected patients than ITPA genotype.. Clin Chem Lab Med 53(12):2021-9 PMID: 25968438
- 8. Yamamoto K et al.. 2010. Inosine triphosphate pyrophosphatase 94C>A polymorphism: clinical implications for patients with systemic lupus erythematosus treated with azathioprine.. Expert Opin Drug Saf 9(3):447-57 PMID: 20367526
