Component

Human nicotinate phosphoribosyltransferase / NAPRT

Human Preiss–Handler enzyme using nicotinic acid and PRPP.

6 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What it acts on

  1. Human NAPRT catalyzes phosphoribosyl transfer from PRPP to nicotinic acid, producing nicotinic acid mononucleotide and pyrophosphate.

    Human nicotinate phosphoribosyltransferase / NAPRT → Nicotinic acid mononucleotide source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/naprt2015.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1606, "file_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe", "text_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe"}
    experimental_model
    Recombinant human NAPRT crystallography and docking; purified protein, no intact tissue
    exposure
    Biochemical or structural assay; no dietary intervention
    limitations
    Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    Nicotinic acid enters its NAD-building route through NAPRT.
    primary_references
    [b3-pre-naprt2015] Crystal structure of human nicotinic acid phosphoribosyltransferase. (2015). https://pubmed.ncbi.nlm.nih.gov/26042198/ DOI: 10.1016/j.fob.2015.05.002
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 249–260

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human NAPRT crystallography and docking; purified protein, no intact tissue · source_derived_draft · unverified_draft

    ### b3-pre-naprt-reaction Human NAPRT catalyzes phosphoribosyl transfer from PRPP to nicotinic acid, producing nicotinic acid mononucleotide and pyrophosphate. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Nicotinic acid enters its NAD-building route through NAPRT. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant human NAPRT crystallography and docking; purified protein, no intact tissue limitations: Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes. exposure: Biochemical or structural assay; no dietary intervention evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/naprt2015.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1606, "file_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe", "text_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe"} [b3-pre-naprt2015] Crystal structure of human nicotinic acid phosphoribosyltransferase. (2015). https://pubmed.ncbi.nlm.nih.gov/26042198/ DOI: 10.1016/j.fob.2015.05.002
    Complete structured claim and evidence

What acts on it

  1. ATP stimulated or inhibited recombinant human NAPRT depending on low or high substrate saturation in the reported kinetic assays.

    ATP → Human nicotinate phosphoribosyltransferase / NAPRT source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/naprt2011.abstract.txt", "locator": "Indexed primary abstract; identified exact passage", "start_char": 645, "end_char": 876, "file_sha256": "c9f4959ad65f0b0621179b3ccf00c460f7f648293bf910209ecc6e7785417deb", "text_sha256": "4c7ca81c7fa47c688d3b609b934e21bddf5bb0501b5bd8b54699ff7761280cb9"}
    experimental_model
    Purified recombinant human NAPRT kinetic assays and site-directed mutagenesis
    exposure
    Biochemical or structural assay; no dietary intervention
    limitations
    Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    ATP’s effect on this enzyme depended on the assay conditions.
    primary_references
    [b3-pre-naprt2011] Characterization of human nicotinate phosphoribosyltransferase: Kinetic studies, structure prediction and functional analysis by site-directed mutagenesis. (2012). https://pubmed.ncbi.nlm.nih.gov/21742010/ DOI: 10.1016/j.biochi.2011.06.033
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 276–287

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human NAPRT kinetic assays and site-directed mutagenesis · source_derived_draft · unverified_draft

    ### b3-pre-naprt-atp-context ATP stimulated or inhibited recombinant human NAPRT depending on low or high substrate saturation in the reported kinetic assays. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: ATP’s effect on this enzyme depended on the assay conditions. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified recombinant human NAPRT kinetic assays and site-directed mutagenesis limitations: Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes. exposure: Biochemical or structural assay; no dietary intervention evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/naprt2011.abstract.txt", "locator": "Indexed primary abstract; identified exact passage", "start_char": 645, "end_char": 876, "file_sha256": "c9f4959ad65f0b0621179b3ccf00c460f7f648293bf910209ecc6e7785417deb", "text_sha256": "4c7ca81c7fa47c688d3b609b934e21bddf5bb0501b5bd8b54699ff7761280cb9"} [b3-pre-naprt2011] Characterization of human nicotinate phosphoribosyltransferase: Kinetic studies, structure prediction and functional analysis by site-directed mutagenesis. (2012). https://pubmed.ncbi.nlm.nih.gov/21742010/ DOI: 10.1016/j.biochi.2011.06.033
    Complete structured claim and evidence

  2. Inorganic phosphate activated purified recombinant human NAPRT in the reported kinetic experiments.

    Inorganic phosphate → Human nicotinate phosphoribosyltransferase / NAPRT source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Phosphorus-containing inorganic phosphate alters a niacin precursor enzyme in vitro; no dietary phosphate deficiency was tested.
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/naprt2011.abstract.txt", "locator": "Indexed primary abstract; identified exact passage", "start_char": 815, "end_char": 876, "file_sha256": "c9f4959ad65f0b0621179b3ccf00c460f7f648293bf910209ecc6e7785417deb", "text_sha256": "53af728f32d65092c92246c77801e92e521892adac900df62bf3f8206129f714"}
    experimental_model
    Purified recombinant human NAPRT kinetic assays and site-directed mutagenesis
    exposure
    Biochemical or structural assay; no dietary intervention
    limitations
    Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    Phosphate supported this isolated precursor enzyme.
    primary_references
    [b3-pre-naprt2011] Characterization of human nicotinate phosphoribosyltransferase: Kinetic studies, structure prediction and functional analysis by site-directed mutagenesis. (2012). https://pubmed.ncbi.nlm.nih.gov/21742010/ DOI: 10.1016/j.biochi.2011.06.033
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 262–274

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human NAPRT kinetic assays and site-directed mutagenesis · source_derived_draft · unverified_draft

    ### b3-pre-naprt-phosphate Inorganic phosphate activated purified recombinant human NAPRT in the reported kinetic experiments. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Phosphate supported this isolated precursor enzyme. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified recombinant human NAPRT kinetic assays and site-directed mutagenesis limitations: Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes. exposure: Biochemical or structural assay; no dietary intervention cross_nutrient: Phosphorus-containing inorganic phosphate alters a niacin precursor enzyme in vitro; no dietary phosphate deficiency was tested. evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/naprt2011.abstract.txt", "locator": "Indexed primary abstract; identified exact passage", "start_char": 815, "end_char": 876, "file_sha256": "c9f4959ad65f0b0621179b3ccf00c460f7f648293bf910209ecc6e7785417deb", "text_sha256": "53af728f32d65092c92246c77801e92e521892adac900df62bf3f8206129f714"} [b3-pre-naprt2011] Characterization of human nicotinate phosphoribosyltransferase: Kinetic studies, structure prediction and functional analysis by site-directed mutagenesis. (2012). https://pubmed.ncbi.nlm.nih.gov/21742010/ DOI: 10.1016/j.biochi.2011.06.033
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Bacterial PncA converted nicotinamide to nicotinic acid, enabling an alternative deamidated NAD synthesis route in mammalian cells.

    Escherichia coli nicotinamidase PncA → Nicotinic acid source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary full text
    experimental_model
    E. coli PncA genetic experiments, mammalian cancer cells and xenografts.
    limitations
    PncA is bacterial; do not create a human nicotinamidase from this result.
    nutrient_topic
    NAD+ collection; molecular form, preparation, species, exposure and manipulation remain explicit. · NAD+
    plain_language
    Microbes can redirect one vitamin form into another route around a blocked enzyme.
    primary_references
    Bacteria Boost Mammalian Host NAD Metabolism by Engaging the Deamidated Biosynthesis Pathway. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32130883/ · DOI 10.1016/j.cmet.2020.02.001

    NAD+: compartmental supply, consumption and cross-nutrient mechanisms (2026-09-19) · lines 164–170

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · E. coli PncA genetic experiments, mammalian cancer cells and xenografts. · source_derived_draft · unverified_draft

    ## nad-plus-microbial-deamidation Microbes can redirect one vitamin form into another route around a blocked enzyme. Bacterial PncA converted nicotinamide to nicotinic acid, enabling an alternative deamidated NAD synthesis route in mammalian cells. Model: E. coli PncA genetic experiments, mammalian cancer cells and xenografts. Limitations: PncA is bacterial; do not create a human nicotinamidase from this result. Evidence access: Primary full text Bacteria Boost Mammalian Host NAD Metabolism by Engaging the Deamidated Biosynthesis Pathway. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32130883/ · DOI 10.1016/j.cmet.2020.02.001
    Complete structured claim and evidence

  2. Removing bacterial PncA abolished, and supplying it enabled, bacterial protection against NAMPT inhibitors in the tested cancer-cell and xenograft systems.

    Escherichia coli nicotinamidase PncA → NAMPT-inhibitor-induced cancer-cell killing source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_access
    Primary full text
    experimental_model
    Microbial genetic manipulation plus mammalian cancer models.
    limitations
    Preclinical resistance mechanism, not guidance to manipulate microbiota during cancer treatment.
    nutrient_topic
    NAD+ collection; molecular form, preparation, species, exposure and manipulation remain explicit. · NAD+
    plain_language
    An alternative precursor source can defeat a blockade of salvage.
    primary_references
    Bacteria Boost Mammalian Host NAD Metabolism by Engaging the Deamidated Biosynthesis Pathway. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32130883/ · DOI 10.1016/j.cmet.2020.02.001
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    NAD+: compartmental supply, consumption and cross-nutrient mechanisms (2026-09-19) · lines 172–178

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Microbial genetic manipulation plus mammalian cancer models. · source_derived_draft · unverified_draft

    ## nad-plus-microbial-rescue An alternative precursor source can defeat a blockade of salvage. Removing bacterial PncA abolished, and supplying it enabled, bacterial protection against NAMPT inhibitors in the tested cancer-cell and xenograft systems. Model: Microbial genetic manipulation plus mammalian cancer models. Limitations: Preclinical resistance mechanism, not guidance to manipulate microbiota during cancer treatment. Evidence access: Primary full text Bacteria Boost Mammalian Host NAD Metabolism by Engaging the Deamidated Biosynthesis Pathway. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32130883/ · DOI 10.1016/j.cmet.2020.02.001
    Complete structured claim and evidence

  3. NAPRT knockdown reversed the rise in cellular NAD caused by nicotinic acid in the cultured human cells studied.

    Human NAPRT knockdown → NAD+ source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/hara2007.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1634, "file_sha256": "4a605e0551bc9453dec63e8aa1e0fcd78985ae7dfca8d4b785039de0e0382547", "text_sha256": "4a605e0551bc9453dec63e8aa1e0fcd78985ae7dfca8d4b785039de0e0382547"}
    experimental_model
    Cultured human cells with endogenous NAPRT and experimental NAPRT knockdown; separate mouse expression measurements
    exposure
    NAPRT knockdown plus nicotinic acid; concentration and duration not independently available in indexed abstract
    limitations
    The abstract does not specify the cell line or dosing details; no inference to oral intake or patient response.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    Nicotinic acid could not produce the same NAD rise after its entry enzyme was suppressed.
    primary_references
    [b3-pre-hara2007] Elevation of cellular NAD levels by nicotinic acid and involvement of nicotinic acid phosphoribosyltransferase in human cells. (2007). https://pubmed.ncbi.nlm.nih.gov/17604275/ DOI: 10.1074/jbc.m610357200
    tissue_or_cell_type
    Cultured human cells expressing endogenous NAPRT
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 289–300

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cultured human cells with endogenous NAPRT and experimental NAPRT knockdown; separate mouse expression measurements · source_derived_draft · unverified_draft

    ### b3-pre-naprt-knockdown-na NAPRT knockdown reversed the rise in cellular NAD caused by nicotinic acid in the cultured human cells studied. Condition category: machinery_impairment nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Nicotinic acid could not produce the same NAD rise after its entry enzyme was suppressed. organism: Homo sapiens tissue_or_cell_type: Cultured human cells expressing endogenous NAPRT experimental_model: Cultured human cells with endogenous NAPRT and experimental NAPRT knockdown; separate mouse expression measurements limitations: The abstract does not specify the cell line or dosing details; no inference to oral intake or patient response. exposure: NAPRT knockdown plus nicotinic acid; concentration and duration not independently available in indexed abstract evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/hara2007.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1634, "file_sha256": "4a605e0551bc9453dec63e8aa1e0fcd78985ae7dfca8d4b785039de0e0382547", "text_sha256": "4a605e0551bc9453dec63e8aa1e0fcd78985ae7dfca8d4b785039de0e0382547"} [b3-pre-hara2007] Elevation of cellular NAD levels by nicotinic acid and involvement of nicotinic acid phosphoribosyltransferase in human cells. (2007). https://pubmed.ncbi.nlm.nih.gov/17604275/ DOI: 10.1074/jbc.m610357200
    Complete structured claim and evidence

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

    This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

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