Component

Human FAD synthetase isoform 2

FLAD1-encoded isoform 2 tested as a recombinant protein; distinct from isoform 1.

5 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. Recombinant human FLAD1 isoforms 1 and 2 exhibited FAD synthetase activity; isoform 2 was purified, and activity required MgCl2.

    Human FAD synthetase isoform 2 → FAD source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    B2 activation and Mg-dependent FAD synthesis provide a biochemical partner to B1-dependent complexes; direct transfer of newly made FAD to DLD was not tested.
    evidence
    [{"paper_key": "brizio-2006-fad", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}]
    experimental_model
    Recombinant human FLAD1 isoforms expressed in E. coli.
    limitations
    No tissue Mg threshold or combined B1/B2 deficiency experiment.
    nutrient
    Thiamine (vitamin B1) · Thiamine (vitamin B1)
    nutrient_topic
    Thiamine research collection; topical membership is not evidence of a direct dietary effect. · Thiamine (vitamin B1)
    organism
    Homo sapiens
    plain_language
    The flavin used by E3 must first be made from the riboflavin pathway. This distinct magnesium-dependent synthesis reaction should not be confused with magnesium binding to B1 enzymes.
    primary_references
    [brizio-2006-fad] Over-expression in Escherichia coli and characterization of two recombinant isoforms of human FAD synthetase (2006). https://pubmed.ncbi.nlm.nih.gov/16643857/ DOI: 10.1016/j.bbrc.2006.04.003
    tissue_or_cell_type
    Purified/expressed proteins

    Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 745–757

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human FLAD1 isoforms expressed in E. coli. · source_derived_draft · unverified_draft

    ### b1-fad-b2-cofactor-synthesis Recombinant human FLAD1 isoforms 1 and 2 exhibited FAD synthetase activity; isoform 2 was purified, and activity required MgCl2. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: The flavin used by E3 must first be made from the riboflavin pathway. This distinct magnesium-dependent synthesis reaction should not be confused with magnesium binding to B1 enzymes. organism: Homo sapiens tissue_or_cell_type: Purified/expressed proteins experimental_model: Recombinant human FLAD1 isoforms expressed in E. coli. limitations: No tissue Mg threshold or combined B1/B2 deficiency experiment. evidence: [{"paper_key": "brizio-2006-fad", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}] cross_nutrient: B2 activation and Mg-dependent FAD synthesis provide a biochemical partner to B1-dependent complexes; direct transfer of newly made FAD to DLD was not tested. nutrient: Thiamine (vitamin B1) [brizio-2006-fad] Over-expression in Escherichia coli and characterization of two recombinant isoforms of human FAD synthetase (2006). https://pubmed.ncbi.nlm.nih.gov/16643857/ DOI: 10.1016/j.bbrc.2006.04.003
    Complete structured claim and evidence

  2. Human FAD synthase isoform 2 adenylylates FMN with ATP to form FAD and pyrophosphate.

    Human FAD synthetase isoform 2 → Flavin mononucleotide source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    FAD synthesis and reverse pyrophosphorolysis assays
    experimental_model
    Purified recombinant human FADS2 catalytic assays
    exposure
    ATP and FMN in FAD-synthesis assays.
    limitations
    Adenylylation is distinct from RFK phosphorylation; reaction products should not be conflated.
    nutrient_topic
    Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
    organism
    Homo sapiens
    plain_language
    FLAD1 performs the second activation step, making FAD from FMN.
    primary_references
    [transport-fads2-2011] Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. (2011). https://pubmed.ncbi.nlm.nih.gov/21951714/ DOI: 10.1111/j.1742-4658.2011.08368.x
    tissue_or_cell_type
    Purified protein

    Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 320–331

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human FADS2 catalytic assays · source_derived_draft · unverified_draft

    ### transport-flad1-adenylylation Human FAD synthase isoform 2 adenylylates FMN with ATP to form FAD and pyrophosphate. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: FLAD1 performs the second activation step, making FAD from FMN. organism: Homo sapiens tissue_or_cell_type: Purified protein experimental_model: Purified recombinant human FADS2 catalytic assays limitations: Adenylylation is distinct from RFK phosphorylation; reaction products should not be conflated. exposure: ATP and FMN in FAD-synthesis assays. evidence_location: FAD synthesis and reverse pyrophosphorolysis assays [transport-fads2-2011] Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. (2011). https://pubmed.ncbi.nlm.nih.gov/21951714/ DOI: 10.1111/j.1742-4658.2011.08368.x
    Complete structured claim and evidence

  3. Purified human FADS2 retained approximately one FAD per enzyme noncovalently; complete release required extensive denaturation.

    Human FAD synthetase isoform 2 → FAD source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Abstract; bound-FAD measurements
    experimental_model
    Purified His-tagged human FADS2 binding and denaturation assays
    exposure
    Isolated enzyme, chaotrope treatment and denaturation.
    limitations
    Product retention alone does not prove direct delivery to every cellular flavoprotein.
    nutrient_topic
    Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
    organism
    Homo sapiens
    plain_language
    FAD can remain tightly associated with the enzyme that makes it.
    primary_references
    [transport-fads2-2011] Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. (2011). https://pubmed.ncbi.nlm.nih.gov/21951714/ DOI: 10.1111/j.1742-4658.2011.08368.x
    tissue_or_cell_type
    Purified enzyme

    Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 373–384

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified His-tagged human FADS2 binding and denaturation assays · source_derived_draft · unverified_draft

    ### transport-flad1-fad-binding Purified human FADS2 retained approximately one FAD per enzyme noncovalently; complete release required extensive denaturation. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: FAD can remain tightly associated with the enzyme that makes it. organism: Homo sapiens tissue_or_cell_type: Purified enzyme experimental_model: Purified His-tagged human FADS2 binding and denaturation assays limitations: Product retention alone does not prove direct delivery to every cellular flavoprotein. exposure: Isolated enzyme, chaotrope treatment and denaturation. evidence_location: Abstract; bound-FAD measurements [transport-fads2-2011] Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. (2011). https://pubmed.ncbi.nlm.nih.gov/21951714/ DOI: 10.1111/j.1742-4658.2011.08368.x
    Complete structured claim and evidence

  4. FADS2 lacked mitochondrial import/localization in the experiments that imported and localized FADS1.

    Human FAD synthetase isoform 2 → Cytosol source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Abstract; FADS2 comparator
    experimental_model
    Parallel FADS1/FADS2 import and localization comparison
    exposure
    In vitro synthesized and transiently expressed human isoforms.
    limitations
    No import in this assay does not exclude condition-dependent localization outside the tested systems.
    nutrient_topic
    Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
    organism
    Human proteins in mammalian model preparations
    plain_language
    FLAD1 isoforms differ in access to the mitochondrial compartment.
    primary_references
    [transport-fads-localization-2010] Mitochondrial localization of human FAD synthetase isoform 1. (2010). https://pubmed.ncbi.nlm.nih.gov/20060505/ DOI: 10.1016/j.mito.2009.12.149
    tissue_or_cell_type
    Rat liver mitochondria; BHK-21 and Caco-2 cells

    Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 360–371

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Parallel FADS1/FADS2 import and localization comparison · source_derived_draft · unverified_draft

    ### transport-flad1-isoform2-compartment FADS2 lacked mitochondrial import/localization in the experiments that imported and localized FADS1. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: FLAD1 isoforms differ in access to the mitochondrial compartment. organism: Human proteins in mammalian model preparations tissue_or_cell_type: Rat liver mitochondria; BHK-21 and Caco-2 cells experimental_model: Parallel FADS1/FADS2 import and localization comparison limitations: No import in this assay does not exclude condition-dependent localization outside the tested systems. exposure: In vitro synthesized and transiently expressed human isoforms. evidence_location: Abstract; FADS2 comparator [transport-fads-localization-2010] Mitochondrial localization of human FAD synthetase isoform 1. (2010). https://pubmed.ncbi.nlm.nih.gov/20060505/ DOI: 10.1016/j.mito.2009.12.149
    Complete structured claim and evidence

What acts on it

  1. Purified human FADS2 showed a strict MgCl2 requirement in the reported spectrophotometric FAD-synthesis assay.

    Mg2+ → Human FAD synthetase isoform 2 source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Magnesium is a cofactor for a vitamin B2 activation step.
    evidence_location
    Abstract and activity assay
    experimental_model
    Recombinant human FADS2 expressed in E. coli and purified
    exposure
    MgCl2 requirement tested in purified enzyme assays.
    limitations
    Assay-specific metal dependence does not quantify human dietary magnesium effects on flavins.
    nutrient_topic
    Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
    organism
    Homo sapiens protein
    plain_language
    Magnesium supports enzymatic conversion of FMN into FAD.
    primary_references
    [transport-fads2-2007] Over-expression in Escherichia coli, purification and characterization of isoform 2 of human FAD synthetase. (2007). https://doi.org/10.1016/j.pep.2006.09.002 DOI: 10.1016/j.pep.2006.09.002
    tissue_or_cell_type
    Purified enzyme

    Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 333–345

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human FADS2 expressed in E. coli and purified · source_derived_draft · unverified_draft

    ### transport-flad1-magnesium-requirement Purified human FADS2 showed a strict MgCl2 requirement in the reported spectrophotometric FAD-synthesis assay. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium supports enzymatic conversion of FMN into FAD. organism: Homo sapiens protein tissue_or_cell_type: Purified enzyme experimental_model: Recombinant human FADS2 expressed in E. coli and purified limitations: Assay-specific metal dependence does not quantify human dietary magnesium effects on flavins. exposure: MgCl2 requirement tested in purified enzyme assays. cross_nutrient: Magnesium is a cofactor for a vitamin B2 activation step. evidence_location: Abstract and activity assay [transport-fads2-2007] Over-expression in Escherichia coli, purification and characterization of isoform 2 of human FAD synthetase. (2007). https://doi.org/10.1016/j.pep.2006.09.002 DOI: 10.1016/j.pep.2006.09.002
    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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