GO:0004516 nicotinate phosphoribosyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004516 describes the enzyme activity that converts nicotinate (niacin) into nicotinate beta-D-ribonucleotide, the first committed step of the Preiss-Handler NAD+ salvage pathway.
• The reaction consumes ATP, 5-phospho-alpha-D-ribose 1-diphosphate (PRPP), and water, releasing ADP, phosphate, and diphosphate.
• NAPRT is the primary human gene encoding this activity, and its expression determines whether cells can use extracellular nicotinate for NAD+ synthesis.
• Beyond metabolism, NAPRT can be secreted and act as a ligand for Toll-like receptor 4, linking this enzymatic activity to inflammation.
• Loss of NAPRT-mediated NAD+ production impairs colon tissue resilience and promotes tumorigenesis in preclinical models.
• Small-molecule modulators and continuous fluorometric assays now enable high-throughput targeting of this activity for cancer and metabolic research.
Description
Nicotinate phosphoribosyltransferase (NAPRT) activity, annotated as GO:0004516, is a molecular function that catalyzes the first and rate-limiting step of the Preiss-Handler pathway for NAD+ biosynthesis. This activity converts nicotinate, a dietary and microbial-derived form of vitamin B3, into nicotinate beta-D-ribonucleotide, thereby feeding into the NAD+ pool that supports redox reactions, DNA repair, and signaling. Because NAD+ homeostasis is central to aging, inflammation, and cancer metabolism, researchers increasingly study GO:0004516 to understand how cells adapt to metabolic stress and to identify therapeutic vulnerabilities. The enzymatic activity is conserved from yeast to humans, and its kinetic properties have been characterized in detail using HPLC-based assays. Recent work has also revealed that NAPRT can be secreted and engage Toll-like receptor 4, expanding its functional repertoire beyond intracellular metabolism. This article integrates authoritative QuickGO annotation with verified PubMed literature to provide a research-grade overview of GO:0004516, its genes, disease links, and experimental models.
nicotinate phosphoribosyltransferase activity At A Glance
| GO ID | GO:0004516 |
|---|---|
| GO term | nicotinate phosphoribosyltransferase activity |
| Ontology | molecular_function |
| Synonym | niacin ribonucleotidase activity; nicotinate-nucleotide:diphosphate phospho-alpha-D-ribosyltransferase activity; nicotinic acid mononucleotide glycohydrolase activity; nicotinic acid mononucleotide pyrophosphorylase activity; nicotinic acid phosphoribosyltransferase activity |
| Major function | Catalyzes the first step of the Preiss-Handler NAD+ salvage pathway, converting nicotinate to nicotinate beta-D-ribonucleotide. |
| Reaction | nicotinate + 5-phospho-alpha-D-ribose 1-diphosphate + ATP + H2O = nicotinate beta-D-ribonucleotide + ADP + phosphate + diphosphate. |
| Primary human gene | NAPRT (nicotinate phosphoribosyltransferase). |
| Pathway context | Preiss-Handler pathway for NAD+ biosynthesis from nicotinate. |
| Subcellular localization | Cytosolic; also detected extracellularly where it can signal via TLR4. |
What Is GO:0004516?
GO:0004516, nicotinate phosphoribosyltransferase activity, is defined by the catalysis of the reaction: nicotinate + 5-phospho-alpha-D-ribose 1-diphosphate + ATP + H2O = nicotinate beta-D-ribonucleotide + ADP + phosphate + diphosphate. In simpler terms, this activity attaches a ribose-phosphate moiety from PRPP to nicotinate, using ATP hydrolysis to drive the reaction, and releases the product nicotinate mononucleotide along with ADP, phosphate, and diphosphate. This is the committed step for NAD+ synthesis from nicotinate in the Preiss-Handler pathway.
Why Is nicotinate phosphoribosyltransferase activity Important in Cell Biology?
GO:0004516 is important because it governs the entry of nicotinate into the NAD+ pool, a critical determinant of cellular energy metabolism, redox balance, and survival under stress. Dysregulation of this activity has been linked to cancer cell dependence on NAD+ salvage, inflammatory signaling, and tissue resilience in the colon. Pharmacological modulation of NAPRT is being explored as a strategy to selectively kill cancer cells or to boost NAD+ in aging-related conditions. Moreover, the recent discovery that trigonelline, a nicotinate-related compound, acts as an NAD+ precursor and improves muscle function during aging highlights the translational potential of targeting this pathway.
• Provides the primary route for dietary nicotinate to enter NAD+ biosynthesis via the Preiss-Handler pathway.
• Supports cellular NAD+ homeostasis required for redox reactions, DNA repair, and sirtuin signaling.
• Enables colon tissue resilience and suppresses tumorigenesis in preclinical models.
• Secreted NAPRT can bind TLR4 and mediate inflammation, linking metabolism to innate immunity.
• Represents a therapeutic target in cancer, where NAD+ salvage is often upregulated.
• Small-molecule modulators of NAPRT are under development for metabolic and oncological applications.
• Continuous fluorometric assays facilitate high-throughput screening for NAPRT-targeting drugs.
• Trigonelline, a related NAD+ precursor, improves muscle function during aging, underscoring the pathway's role in sarcopenia.
• Kinetic characterization of yeast NAPRT provides a foundation for understanding human enzyme regulation.
• NAPRT expression status may predict response to NAD+-lowering therapies in cancer.
Molecular Mechanism of nicotinate phosphoribosyltransferase activity
Substrate binding and PRPP utilization
In simple terms: The enzyme grabs nicotinate and a ribose-phosphate donor to start the reaction.
NAPRT binds nicotinate and 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) in an ordered manner, with PRPP serving as the phosphoribosyl donor. The enzyme uses ATP hydrolysis to energize the transfer, releasing ADP and inorganic phosphate. This step is the committed and rate-limiting reaction of the Preiss-Handler pathway.
Catalytic mechanism and product formation
In simple terms: The enzyme attaches the ribose-phosphate to nicotinate, forming a NAD+ precursor.
The catalytic mechanism involves the formation of a covalent enzyme-PRPP intermediate, followed by transfer of the phosphoribosyl group to nicotinate, yielding nicotinate beta-D-ribonucleotide and releasing diphosphate. This product is then adenylylated to form NAD+ in subsequent steps of the Preiss-Handler pathway.
Cofactors and energy coupling
In simple terms: ATP provides the energy needed to drive the reaction forward.
ATP is hydrolyzed to ADP and phosphate during the reaction, coupling the exergonic hydrolysis to the endergonic phosphoribosyl transfer. This energy coupling ensures efficient conversion of nicotinate to its mononucleotide under physiological conditions.
Regulation by substrate availability and enzyme expression
In simple terms: The amount of enzyme and the supply of nicotinate control how fast the reaction goes.
NAPRT activity is primarily regulated by the availability of nicotinate and PRPP, as well as by transcriptional control of the NAPRT gene. In cancer cells, NAPRT expression is often elevated to sustain NAD+ levels, and its activity can be modulated by small-molecule inhibitors or activators.
Extracellular roles and non-canonical functions
In simple terms: The enzyme can also leave the cell and send inflammatory signals.
Beyond its intracellular metabolic role, NAPRT can be secreted and bind Toll-like receptor 4, triggering inflammatory signaling. This extracellular function expands the biological impact of GO:0004516 beyond NAD+ biosynthesis and highlights its relevance in inflammation and immunity.
Key Genes Involved in GO:0004516 nicotinate phosphoribosyltransferase activity
The following genes and proteins are directly associated with nicotinate phosphoribosyltransferase activity (GO:0004516) or its regulatory network.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NAPRT | Encodes the human nicotinate phosphoribosyltransferase enzyme that catalyzes GO:0004516. | Central to NAD+ salvage, cancer metabolism, and inflammation research. |
| NADSYN1 | Encodes NAD synthetase, which converts nicotinate mononucleotide to NAD+ downstream of NAPRT. | Completes the Preiss-Handler pathway; potential target for metabolic studies. |
| QPRT | Encodes quinolinate phosphoribosyltransferase, involved in de novo NAD+ synthesis. | Provides alternative route to NAD+; useful for comparative studies. |
| NMNAT1 | Encodes nicotinamide mononucleotide adenylyltransferase 1, which adenylylates nicotinate mononucleotide. | Links NAPRT activity to NAD+ production; relevant in neurodegeneration. |
| NMNAT2 | Encodes NMNAT2, a neuronal survival factor that utilizes nicotinate mononucleotide. | Implicated in axon degeneration and NAD+ homeostasis. |
| NMNAT3 | Encodes mitochondrial NMNAT3, which can use nicotinate mononucleotide. | Mitochondrial NAD+ regulation; metabolic research. |
| NAMPT | Encodes nicotinamide phosphoribosyltransferase, the rate-limiting enzyme in the salvage pathway from nicotinamide. | Often compared with NAPRT for NAD+ dependency in cancer. |
| NMRK1 | Encodes nicotinamide riboside kinase 1, which feeds into NAD+ synthesis. | Alternative NAD+ precursor pathway; relevant to aging research. |
| NMRK2 | Encodes nicotinamide riboside kinase 2, another NAD+ salvage enzyme. | Tissue-specific NAD+ metabolism. |
| SIRT1 | NAD+-dependent deacetylase that senses NAD+ levels generated partly via NAPRT. | Links NAPRT activity to aging, metabolism, and inflammation. |
| PARP1 | NAD+-consuming enzyme in DNA repair; its activity depends on NAD+ pools. | Synthetic lethality with NAPRT inhibition in cancer. |
| TLR4 | Toll-like receptor 4 binds secreted NAPRT to mediate inflammation. | Innate immunity and inflammation research. |
| NAPRT (yeast) | Yeast ortholog used for kinetic studies of GO:0004516. | Model organism for enzyme kinetics and inhibitor testing. |
| Trigonelline | An NAD+ precursor derived from nicotinate metabolism that improves muscle function. | Aging and sarcopenia research. |
| NAPRT inhibitors | Small molecules that modulate NAPRT activity. | Cancer therapy development. |
| Fluorometric assay probes | Chemical tools for continuous measurement of NAPRT activity. | High-throughput screening. |
| Benzimidazole modulators | A class of NAPRT modulators. | Pharmacological tool compounds. |
How Is nicotinate phosphoribosyltransferase activity Regulated?
NAPRT activity is regulated at multiple levels. Transcriptionally, NAPRT expression is induced by metabolic stress and in certain cancers to maintain NAD+ levels. Post-translationally, the enzyme can be secreted, where it acts as a TLR4 ligand, linking its regulation to inflammatory cues. Additionally, substrate availability of nicotinate and PRPP directly influences catalytic flux through GO:0004516. Pharmacological modulation with small molecules such as benzimidazoles can inhibit or activate NAPRT, providing a means to regulate the pathway.
nicotinate phosphoribosyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NAPRT | Colon tumorigenesis and tissue resilience | NAPRT knockout colon organoids and mouse models |
| NAPRT | Inflammation via TLR4 signaling | NAPRT overexpression and secretion assays in immune cells |
| NAPRT | Cancer NAD+ dependency | NAPRT knockdown cancer cell lines and xenografts |
| NAPRT | Sarcopenia and muscle aging | Trigonelline supplementation in aged mice |
| NAPRT | Metabolic disorders | NAPRT point-mutation knock-in mice to alter catalytic activity |
Cancer metabolism and NAD+ dependency
Many cancer cells rely on NAD+ salvage to support rapid proliferation and DNA repair. NAPRT-mediated NAD+ biosynthesis enhances colon tissue resiliency and suppresses tumorigenesis in preclinical models, but in established tumors, NAPRT can also support cancer cell survival. Inhibitors of NAD+ production, including NAPRT inhibitors, are being explored as anticancer agents. The expression level of NAPRT may determine sensitivity to NAD+-lowering therapies.
Inflammation and innate immunity
Secreted NAPRT binds Toll-like receptor 4 and mediates inflammation, revealing a non-metabolic role for this enzyme. This finding links GO:0004516 to inflammatory diseases and suggests that modulating NAPRT activity could have immunomodulatory effects.
Aging and sarcopenia
Trigonelline, an NAD+ precursor related to nicotinate metabolism, improves muscle function during aging and is reduced in human sarcopenia. This suggests that the Preiss-Handler pathway, including NAPRT activity, may influence muscle health and age-related decline.
From nicotinate phosphoribosyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of NAPRT affect NAD+ levels and colon tumorigenesis? | NAPRT knockout colon organoids and Apc-mutant mice |
| Can NAPRT catalytic activity be selectively inhibited? | Point-mutation knock-in of catalytic residues in cancer cell lines |
| Does secreted NAPRT require TLR4 for inflammatory signaling? | NAPRT overexpression with TLR4 knockout macrophages |
| What is the role of NAPRT in muscle aging? | NAPRT knockout and trigonelline-treated aged mice |
| Can NAPRT be used as a biomarker for NAD+ therapy? | Knock-in reporter cell lines and patient-derived organoids |
| How does NAPRT expression affect sensitivity to NAD+-lowering drugs? | NAPRT overexpression and knockout isogenic cancer cell lines |
How to Study the nicotinate phosphoribosyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Continuous fluorometric assay | Real-time NAPRT enzymatic activity | High-throughput inhibitor screening |
| HPLC kinetics | Substrate conversion and reaction rates | Enzyme mechanism studies |
| CRISPR knockout screens | Gene dependencies and synthetic lethality | Identifying combination targets with NAPRT inhibition |
| Metabolomics (LC-MS) | NAD+ and precursor levels | Assessing pathway flux in cells and tissues |
| Co-immunoprecipitation | Protein-protein interactions (e.g., NAPRT-TLR4) | Validating extracellular signaling roles |
| Secretion ELISA | Extracellular NAPRT levels | Inflammation studies |
| Organoid culture | Tissue resilience and tumorigenesis | Colon cancer modeling |
| Mouse xenografts | Tumor growth and NAD+ dependency | Preclinical drug testing |
Enzymatic activity assays
Continuous fluorometric assays have been developed to measure NAPRT activity in real time, enabling high-throughput screening of modulators. HPLC-based kinetic analysis remains a gold standard for detailed characterization of reaction rates and substrate specificity.
CRISPR-based genetic screens
Genome-wide CRISPR knockout screens can identify genes that modulate sensitivity to NAPRT inhibition, revealing synthetic lethal interactions. Such screens help pinpoint pathways that compensate for loss of GO:0004516 activity.
Metabolomics and NAD+ quantification
Mass spectrometry-based metabolomics allows direct measurement of NAD+ and its precursors, including nicotinate mononucleotide, to assess flux through the Preiss-Handler pathway. This approach is essential for linking NAPRT activity to cellular metabolic states.
Protein interaction and secretion studies
Co-immunoprecipitation and surface plasmon resonance can detect NAPRT binding to TLR4, while secretion assays quantify extracellular NAPRT levels. These methods clarify the non-canonical roles of the enzyme.
How CRISPR Can Be Used to Study GO:0004516 nicotinate phosphoribosyltransferase activity
Knockout
CRISPR knockout of NAPRT in cell lines and organoids can abolish GO:0004516 activity, leading to reduced NAD+ levels and impaired growth under metabolic stress. Such models are valuable for studying the contribution of the Preiss-Handler pathway to cancer and tissue resilience.
Point Mutation
Introducing point mutations in catalytic residues of NAPRT can dissect the enzymatic mechanism and separate catalytic activity from non-canonical functions such as TLR4 binding. These models help determine which phenotypes depend on the phosphoribosyltransferase activity itself.
Knock-in
Knock-in of tagged NAPRT (e.g., FLAG or GFP) allows tracking of protein localization, secretion, and interaction partners in physiological contexts. This approach can also be used to express mutant NAPRT under the endogenous promoter to study regulation.
Overexpression
Overexpression of NAPRT in cancer cell lines or primary cells can increase NAD+ levels and confer resistance to NAD+-lowering agents. It is also useful for producing recombinant enzyme for biochemical assays and structural studies.
How EDITGENE Supports nicotinate phosphoribosyltransferase activity Research
Researchers studying nicotinate phosphoribosyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in NAD+ metabolism, inflammation, or tumorigenesis. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models that enable such causal inferences.
Contact EDITGENE today to design your custom CRISPR model for nicotinate phosphoribosyltransferase activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| NAPRT Knockout HEK293 Cell Line | EDJ-KQ11164 | Human | 93100 | Details Get a Quote |
| NAPRT Knockout A-549 Cell Line | EDJ-KQ39179 | Human | 93100 | Details Get a Quote |
| NAPRT Knockout HCT 116 Cell Line | EDJ-KQ39180 | Human | 93100 | Details Get a Quote |
| NAPRT Knockout HeLa Cell Line | EDJ-KQ39181 | Human | 93100 | Details Get a Quote |
Displaying Records 1 To 4 Of 4 Records
Frequently Asked Questions About nicotinate phosphoribosyltransferase activity
What is nicotinate phosphoribosyltransferase activity?
It is the enzyme activity (GO:0004516) that converts nicotinate to nicotinate beta-D-ribonucleotide, the first step in the Preiss-Handler NAD+ salvage pathway.
What genes are involved in nicotinate phosphoribosyltransferase activity?
The primary human gene is NAPRT; other pathway genes include NADSYN1, NMNAT1-3, and QPRT.
What is the role of NAPRT in cancer?
NAPRT supports NAD+ production that cancer cells need for survival and proliferation; its inhibition is being explored as an anticancer strategy.
How is nicotinate phosphoribosyltransferase activity measured?
It can be measured using continuous fluorometric assays or HPLC-based kinetic methods.
What is the Preiss-Handler pathway?
It is a NAD+ biosynthesis route that starts with nicotinate and involves NAPRT, NADSYN1, and NMNAT enzymes.
Can NAPRT be secreted and have extracellular functions?
Yes, secreted NAPRT can bind Toll-like receptor 4 and mediate inflammation.
What diseases are linked to NAPRT dysfunction?
Colon tumorigenesis, inflammation, and age-related muscle decline have been associated with altered NAPRT activity.
What are NAPRT inhibitors?
Small molecules such as benzimidazoles that modulate NAPRT activity, being developed for cancer therapy.
How does trigonelline relate to NAPRT?
Trigonelline is an NAD+ precursor derived from nicotinate metabolism that improves muscle function during aging.
What CRISPR models are available for studying NAPRT?
Knockout, point mutation, knock-in, and overexpression models can be generated to study NAPRT function in various cell types.
Conclusion
GO:0004516, nicotinate phosphoribosyltransferase activity, is a critical enzymatic function that links dietary nicotinate to NAD+ biosynthesis and influences cancer, inflammation, and aging. The integration of QuickGO annotation with verified literature provides a solid foundation for researchers to explore this activity using CRISPR models and biochemical assays. Targeting NAPRT holds promise for therapeutic development in oncology and metabolic diseases.
References
- 1. Membrez M et al.. 2024. Trigonelline is an NAD(+) precursor that improves muscle function during ageing and is reduced in human sarcopenia.. Nat Metab 6(3):433-447 PMID: 38504132
- 2. Gasparrini M et al.. 2021. Enzymology of extracellular NAD metabolism.. Cell Mol Life Sci 78(7):3317-3331 PMID: 33755743
- 3. Hanna LS et al.. 1983. Kinetic analysis of nicotinate phosphoribosyltransferase from yeast using high pressure liquid chromatography.. J Biol Chem 258(16):9745-54 PMID: 6224784
- 4. Wu X et al.. 2026. NAPRT-mediated deamidated NAD biosynthesis enhances colon tissue resiliency and suppresses tumorigenesis.. Nat Commun 17(1) PMID: 41667489
- 5. Minazzato G et al.. 2023. A Versatile Continuous Fluorometric Enzymatic Assay for Targeting Nicotinate Phosphoribosyltransferase.. Molecules 28(3) PMID: 36770640
- 6. Managò A et al.. 2019. Extracellular nicotinate phosphoribosyltransferase binds Toll like receptor 4 and mediates inflammation.. Nat Commun 10(1):4116 PMID: 31511522
- 7. Baldassarri C et al.. 2023. Properly Substituted Benzimidazoles as a New Promising Class of Nicotinate Phosphoribosyltransferase (NAPRT) Modulators.. Pharmaceuticals (Basel) 16(2) PMID: 37259338
- 8. Ghanem MS et al.. 2024. Inhibitors of NAD(+) Production in Cancer Treatment: State of the Art and Perspectives.. Int J Mol Sci 25(4) PMID: 38396769
