Component

Human mitochondrial cytochrome b5 / CYB5B

Human mitochondrial cytochrome b5 / CYB5B. Species, exposure and limitations are retained in each linked claim.

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. Mitochondrial CYB5B was required for the mARC-containing N-reductive system in the studied human cells.

    Human mitochondrial cytochrome b5 / CYB5B → Human mitochondrial amidoxime-reducing component 1 / MTARC1 source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/molybdenum-research/23703616.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec", "start_char": 0, "end_char": 1596, "text_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec"}
    experimental_model
    Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution
    exposure
    mARC, CYB5B and CYB5A depletion; apo-CYB5
    limitations
    Expression-dependent cellular contributions; no clinical iron or B2 supplementation test.
    nutrient_topic
    Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum
    organism
    Homo sapiens; separate mouse Cyb5a knockout
    plain_language
    mARC needs an electron-delivery partner.
    primary_references
    [mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916
    tissue_or_cell_type
    HEK293 and second human cell line; purified proteins

    Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 989–1000

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution · source_derived_draft · unverified_draft

    ### mo-cyb5b-marc Mitochondrial CYB5B was required for the mARC-containing N-reductive system in the studied human cells. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: mARC needs an electron-delivery partner. organism: Homo sapiens; separate mouse Cyb5a knockout tissue_or_cell_type: HEK293 and second human cell line; purified proteins experimental_model: Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution limitations: Expression-dependent cellular contributions; no clinical iron or B2 supplementation test. exposure: mARC, CYB5B and CYB5A depletion; apo-CYB5 evidence_span: {"source_cache": "artifacts/molybdenum-research/23703616.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec", "start_char": 0, "end_char": 1596, "text_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec"} [mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916
    Complete structured claim and evidence

What acts on it

  1. Heme-free apo-CYB5 failed to support N-reduction in the reconstituted system.

    Heme → Human mitochondrial cytochrome b5 / CYB5B source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/molybdenum-research/23703616.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec", "start_char": 0, "end_char": 1596, "text_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec"}
    experimental_model
    Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution
    exposure
    mARC, CYB5B and CYB5A depletion; apo-CYB5
    limitations
    Expression-dependent cellular contributions; no clinical iron or B2 supplementation test.
    nutrient_topic
    Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum
    organism
    Homo sapiens; separate mouse Cyb5a knockout
    plain_language
    Removing the iron-containing heme breaks this electron-transfer step.
    primary_references
    [mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916
    tissue_or_cell_type
    HEK293 and second human cell line; purified proteins

    Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 1002–1013

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution · source_derived_draft · unverified_draft

    ### mo-cyb5b-heme Heme-free apo-CYB5 failed to support N-reduction in the reconstituted system. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: Removing the iron-containing heme breaks this electron-transfer step. organism: Homo sapiens; separate mouse Cyb5a knockout tissue_or_cell_type: HEK293 and second human cell line; purified proteins experimental_model: Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution limitations: Expression-dependent cellular contributions; no clinical iron or B2 supplementation test. exposure: mARC, CYB5B and CYB5A depletion; apo-CYB5 evidence_span: {"source_cache": "artifacts/molybdenum-research/23703616.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec", "start_char": 0, "end_char": 1596, "text_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec"} [mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. CYB5A siRNA in HEK293 cells and Cyb5a knockout in mice did not support a required role for the microsomal isoform in measured N-reduction.

    Human microsomal cytochrome b5 / CYB5A → Human mitochondrial amidoxime-reducing component 1 / MTARC1 source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/molybdenum-research/23703616.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec", "start_char": 0, "end_char": 1596, "text_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec"}
    experimental_model
    Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution
    exposure
    mARC, CYB5B and CYB5A depletion; apo-CYB5
    limitations
    Expression-dependent cellular contributions; no clinical iron or B2 supplementation test.
    nutrient_topic
    Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum
    organism
    Homo sapiens; separate mouse Cyb5a knockout
    plain_language
    The location and identity of the cytochrome b5 partner matter.
    primary_references
    [mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916
    tissue_or_cell_type
    HEK293 and second human cell line; purified proteins

    Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 1015–1026

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution · source_derived_draft · unverified_draft

    ### mo-cyb5a-not-substitute CYB5A siRNA in HEK293 cells and Cyb5a knockout in mice did not support a required role for the microsomal isoform in measured N-reduction. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: The location and identity of the cytochrome b5 partner matter. organism: Homo sapiens; separate mouse Cyb5a knockout tissue_or_cell_type: HEK293 and second human cell line; purified proteins experimental_model: Human-cell siRNA plus recombinant cytochrome-b5/cofactor reconstitution limitations: Expression-dependent cellular contributions; no clinical iron or B2 supplementation test. exposure: mARC, CYB5B and CYB5A depletion; apo-CYB5 evidence_span: {"source_cache": "artifacts/molybdenum-research/23703616.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec", "start_char": 0, "end_char": 1596, "text_sha256": "9034da6c790ca6e0c60dd765eec631ea2875c6caf65f6d15d59733bc5e0ee0ec"} [mo-p23703616] The involvement of mitochondrial amidoxime reducing components 1 and 2 and mitochondrial cytochrome b5 in N-reductive metabolism in human cells. (2013). https://pubmed.ncbi.nlm.nih.gov/23703616/ DOI: 10.1074/jbc.m113.474916
    Complete structured claim and evidence

  2. The reconstituted mARC system used NADH/FAD-dependent cytochrome b5 reductase and heme-containing cytochrome b5.

    Human NADH-cytochrome b5 reductase / CYB5R3 → Human mitochondrial amidoxime-reducing component 1 / MTARC1 source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/molybdenum-research/20861021.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "0f430936dcc4701e5d57040edcab4b0418e3c49c59620e0f7d5f54aff41e7877", "start_char": 0, "end_char": 1557, "text_sha256": "0f430936dcc4701e5d57040edcab4b0418e3c49c59620e0f7d5f54aff41e7877"}
    experimental_model
    Recombinant human mARC1/mARC2 biochemical and spectroscopic reconstitution
    exposure
    N-hydroxylated substrates; cofactor reconstitution
    limitations
    The 2010 paper could not identify the Mo-ligating cysteine; later structural/mutagenesis work resolves that point. Its earlier inference is not imported as current fact.
    nutrient_topic
    Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum
    organism
    Human proteins expressed in Escherichia coli
    plain_language
    Niacin, riboflavin, iron and molybdenum meet in one electron-transfer chain.
    primary_references
    [mo-p20861021] Biochemical and spectroscopic characterization of the human mitochondrial amidoxime reducing components hmARC-1 and hmARC-2 suggests the existence of a new molybdenum enzyme family in eukaryotes. (2010). https://pubmed.ncbi.nlm.nih.gov/20861021/ DOI: 10.1074/jbc.m110.169532
    tissue_or_cell_type
    Purified enzyme system

    Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 963–974

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human mARC1/mARC2 biochemical and spectroscopic reconstitution · source_derived_draft · unverified_draft

    ### mo-marc-fad-nadh The reconstituted mARC system used NADH/FAD-dependent cytochrome b5 reductase and heme-containing cytochrome b5. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: Niacin, riboflavin, iron and molybdenum meet in one electron-transfer chain. organism: Human proteins expressed in Escherichia coli tissue_or_cell_type: Purified enzyme system experimental_model: Recombinant human mARC1/mARC2 biochemical and spectroscopic reconstitution limitations: The 2010 paper could not identify the Mo-ligating cysteine; later structural/mutagenesis work resolves that point. Its earlier inference is not imported as current fact. exposure: N-hydroxylated substrates; cofactor reconstitution evidence_span: {"source_cache": "artifacts/molybdenum-research/20861021.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "0f430936dcc4701e5d57040edcab4b0418e3c49c59620e0f7d5f54aff41e7877", "start_char": 0, "end_char": 1557, "text_sha256": "0f430936dcc4701e5d57040edcab4b0418e3c49c59620e0f7d5f54aff41e7877"} [mo-p20861021] Biochemical and spectroscopic characterization of the human mitochondrial amidoxime reducing components hmARC-1 and hmARC-2 suggests the existence of a new molybdenum enzyme family in eukaryotes. (2010). https://pubmed.ncbi.nlm.nih.gov/20861021/ DOI: 10.1074/jbc.m110.169532
    Complete structured claim and evidence

  3. Reduced human mARC1 generated nitric oxide from nitrite in the reconstituted electron-transfer chain.

    Human mitochondrial amidoxime-reducing component 1 / MTARC1 → Nitrite / NO2(-) source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/molybdenum-research/24500710.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e4c2ab41c945d420266290d0241752039d7de2cb6223f9c64c7d0525c5688d9b", "start_char": 0, "end_char": 1585, "text_sha256": "e4c2ab41c945d420266290d0241752039d7de2cb6223f9c64c7d0525c5688d9b"}
    experimental_model
    Recombinant human mARC1/mARC2, active-site mutation, tungsten replacement and HEK expression
    exposure
    Reduced enzyme, nitrite, NADH/CYB5/CYB5R; pH 7.5 versus 6.5
    limitations
    Shows nitrite-reducing capacity; its share of NO production in normal people and response to mineral intake are not established.
    nutrient_topic
    Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum
    organism
    Homo sapiens proteins and HEK cells
    plain_language
    mARC1 can also make NO from nitrite under suitable conditions.
    primary_references
    [mo-p24500710] Nitrite reductase and nitric-oxide synthase activity of the mitochondrial molybdopterin enzymes mARC1 and mARC2. (2014). https://pubmed.ncbi.nlm.nih.gov/24500710/ DOI: 10.1074/jbc.m114.555177
    tissue_or_cell_type
    Purified redox system and human cell model

    Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 1028–1039

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human mARC1/mARC2, active-site mutation, tungsten replacement and HEK expression · source_derived_draft · unverified_draft

    ### mo-marc1-nitrite Reduced human mARC1 generated nitric oxide from nitrite in the reconstituted electron-transfer chain. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: mARC1 can also make NO from nitrite under suitable conditions. organism: Homo sapiens proteins and HEK cells tissue_or_cell_type: Purified redox system and human cell model experimental_model: Recombinant human mARC1/mARC2, active-site mutation, tungsten replacement and HEK expression limitations: Shows nitrite-reducing capacity; its share of NO production in normal people and response to mineral intake are not established. exposure: Reduced enzyme, nitrite, NADH/CYB5/CYB5R; pH 7.5 versus 6.5 evidence_span: {"source_cache": "artifacts/molybdenum-research/24500710.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e4c2ab41c945d420266290d0241752039d7de2cb6223f9c64c7d0525c5688d9b", "start_char": 0, "end_char": 1585, "text_sha256": "e4c2ab41c945d420266290d0241752039d7de2cb6223f9c64c7d0525c5688d9b"} [mo-p24500710] Nitrite reductase and nitric-oxide synthase activity of the mitochondrial molybdopterin enzymes mARC1 and mARC2. (2014). https://pubmed.ncbi.nlm.nih.gov/24500710/ DOI: 10.1074/jbc.m114.555177
    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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