Component

The colchicine binding site on tubulin

The colchicine binding site on tubulin. Species, exposure and limitations are retained in each linked claim.

3 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 acts on it

  1. Inhibition of colchicine binding to Ascaris suum embryonic tubulin by mebendazole and fenbendazole appeared to be noncompetitive, whereas the same compounds appeared to be competitive inhibitors of colchicine binding to bovine brain tubulin.

    Mebendazole → The colchicine binding site on tubulin source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/mebendazole-research/7388055.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7", "start_char": 0, "end_char": 1209, "text_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7"}
    experimental_model
    Inhibition of tritiated colchicine binding to cytosolic tubulin from 8-day Ascaris suum embryos and from bovine brain
    exposure
    Mebendazole and fenbendazole compared on the two tubulins in the same assay
    limitations
    The founding selectivity result. It measures embryonic tubulin; the study in this collection that measured intestinal tubulin found a far smaller difference.
    nutrient_topic
    Mebendazole research collection; topical membership is not evidence of a direct clinical effect, and mebendazole is recorded separately from albendazole, from the benzimidazole class and from its own crystal forms. · Mebendazole
    organism
    Nematode and cattle
    plain_language
    It does not even bind the two tubulins the same way: it competes with colchicine on ours and not on the worm’s.
    primary_references
    [mbz-p7388055] Interaction of anthelmintic benzimidazoles with Ascaris suum embryonic tubulin. (1980). https://pubmed.ncbi.nlm.nih.gov/7388055/ DOI: 10.1016/0304-4165(80)90431-6
    tissue_or_cell_type
    Embryonic nematode tubulin and bovine brain tubulin

    Mebendazole: the tubulin it binds, why that is selective, the crystal form that decides whether any of it works, and the off-target that became an oncology programme (2026-09-22) · lines 108–119

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Inhibition of tritiated colchicine binding to cytosolic tubulin from 8-day Ascaris suum embryos and from bovine brain · source_derived_draft · unverified_draft

    ### mbz-binding-mode-differs Inhibition of colchicine binding to Ascaris suum embryonic tubulin by mebendazole and fenbendazole appeared to be noncompetitive, whereas the same compounds appeared to be competitive inhibitors of colchicine binding to bovine brain tubulin. Condition category: normal nutrient_topic: Mebendazole research collection; topical membership is not evidence of a direct clinical effect, and mebendazole is recorded separately from albendazole, from the benzimidazole class and from its own crystal forms. plain_language: It does not even bind the two tubulins the same way: it competes with colchicine on ours and not on the worm’s. organism: Nematode and cattle tissue_or_cell_type: Embryonic nematode tubulin and bovine brain tubulin experimental_model: Inhibition of tritiated colchicine binding to cytosolic tubulin from 8-day Ascaris suum embryos and from bovine brain limitations: The founding selectivity result. It measures embryonic tubulin; the study in this collection that measured intestinal tubulin found a far smaller difference. exposure: Mebendazole and fenbendazole compared on the two tubulins in the same assay evidence_span: {"source_cache": "artifacts/mebendazole-research/7388055.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7", "start_char": 0, "end_char": 1209, "text_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7"} [mbz-p7388055] Interaction of anthelmintic benzimidazoles with Ascaris suum embryonic tubulin. (1980). https://pubmed.ncbi.nlm.nih.gov/7388055/ DOI: 10.1016/0304-4165(80)90431-6
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. In vitro incubation of Ascaris suum with 10 micromolar mebendazole resulted in a complete loss of colchicine binding ability of extracts obtained from the parasite intestine, the colchicine binding receptor in those extracts was identified biochemically as tubulin, and that protein comprised approximately 0.8% of the soluble intestinal protein.

    Mebendazole → Nematode beta-tubulin source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/mebendazole-research/7335116.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "358adb37f881bf9fc64cf4cea24ce690792e958df702a705b2addda3295ad144", "start_char": 0, "end_char": 1621, "text_sha256": "358adb37f881bf9fc64cf4cea24ce690792e958df702a705b2addda3295ad144"}
    experimental_model
    Colchicine and tritiated mebendazole binding to partially purified tubulin from Ascaris suum intestine and porcine brain
    exposure
    In vitro incubation of Ascaris suum with 10 micromolar mebendazole, with tubulin partially purified from the intestine
    limitations
    Measures the tissue mebendazole actually damages rather than embryonic tissue, and reaches the opposite conclusion about selectivity. Solubility prevented a precise association constant for mebendazole itself.
    nutrient_topic
    Mebendazole research collection; topical membership is not evidence of a direct clinical effect, and mebendazole is recorded separately from albendazole, from the benzimidazole class and from its own crystal forms. · Mebendazole
    organism
    Nematode and pig
    plain_language
    In the gut of the worm, the drug wipes out the protein it is supposed to act on.
    primary_references
    [mbz-p7335116] Intestinal tubulin as possible target for the chemotherapeutic action of mebendazole in parasitic nematodes. (1981). https://pubmed.ncbi.nlm.nih.gov/7335116/ DOI: 10.1016/0166-6851(81)90064-5
    tissue_or_cell_type
    Nematode intestinal tubulin and porcine brain tubulin

    Mebendazole: the tubulin it binds, why that is selective, the crystal form that decides whether any of it works, and the off-target that became an oncology programme (2026-09-22) · lines 121–132

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Colchicine and tritiated mebendazole binding to partially purified tubulin from Ascaris suum intestine and porcine brain · source_derived_draft · unverified_draft

    ### mbz-intestinal-tubulin-is-the-target In vitro incubation of Ascaris suum with 10 micromolar mebendazole resulted in a complete loss of colchicine binding ability of extracts obtained from the parasite intestine, the colchicine binding receptor in those extracts was identified biochemically as tubulin, and that protein comprised approximately 0.8% of the soluble intestinal protein. Condition category: normal nutrient_topic: Mebendazole research collection; topical membership is not evidence of a direct clinical effect, and mebendazole is recorded separately from albendazole, from the benzimidazole class and from its own crystal forms. plain_language: In the gut of the worm, the drug wipes out the protein it is supposed to act on. organism: Nematode and pig tissue_or_cell_type: Nematode intestinal tubulin and porcine brain tubulin experimental_model: Colchicine and tritiated mebendazole binding to partially purified tubulin from Ascaris suum intestine and porcine brain limitations: Measures the tissue mebendazole actually damages rather than embryonic tissue, and reaches the opposite conclusion about selectivity. Solubility prevented a precise association constant for mebendazole itself. exposure: In vitro incubation of Ascaris suum with 10 micromolar mebendazole, with tubulin partially purified from the intestine evidence_span: {"source_cache": "artifacts/mebendazole-research/7335116.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "358adb37f881bf9fc64cf4cea24ce690792e958df702a705b2addda3295ad144", "start_char": 0, "end_char": 1621, "text_sha256": "358adb37f881bf9fc64cf4cea24ce690792e958df702a705b2addda3295ad144"} [mbz-p7335116] Intestinal tubulin as possible target for the chemotherapeutic action of mebendazole in parasitic nematodes. (1981). https://pubmed.ncbi.nlm.nih.gov/7335116/ DOI: 10.1016/0166-6851(81)90064-5
    Complete structured claim and evidence

  2. The inhibition constants of mebendazole and fenbendazole for Ascaris suum embryonic tubulin were 1.9 x 10-8 and 6.5 x 10-8 molar while those for bovine brain tubulin were 7.3 x 10-6 and 1.7 x 10-5 molar, values 250 to 400 times greater, so that differential binding affinities between nematode and mammalian tubulin may explain the selective toxicity.

    Mebendazole → Nematode beta-tubulin source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/mebendazole-research/7388055.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7", "start_char": 0, "end_char": 1209, "text_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7"}
    experimental_model
    Inhibition of tritiated colchicine binding to cytosolic tubulin from 8-day Ascaris suum embryos and from bovine brain
    exposure
    Mebendazole and fenbendazole compared on the two tubulins in the same assay
    limitations
    The founding selectivity result. It measures embryonic tubulin; the study in this collection that measured intestinal tubulin found a far smaller difference.
    nutrient_topic
    Mebendazole research collection; topical membership is not evidence of a direct clinical effect, and mebendazole is recorded separately from albendazole, from the benzimidazole class and from its own crystal forms. · Mebendazole
    organism
    Nematode and cattle
    plain_language
    The drug grips worm tubulin hundreds of times more tightly than ours, which is the usual explanation for why it is safe.
    primary_references
    [mbz-p7388055] Interaction of anthelmintic benzimidazoles with Ascaris suum embryonic tubulin. (1980). https://pubmed.ncbi.nlm.nih.gov/7388055/ DOI: 10.1016/0304-4165(80)90431-6
    tissue_or_cell_type
    Embryonic nematode tubulin and bovine brain tubulin

    Mebendazole: the tubulin it binds, why that is selective, the crystal form that decides whether any of it works, and the off-target that became an oncology programme (2026-09-22) · lines 95–106

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Inhibition of tritiated colchicine binding to cytosolic tubulin from 8-day Ascaris suum embryos and from bovine brain · source_derived_draft · unverified_draft

    ### mbz-selectivity-250-fold The inhibition constants of mebendazole and fenbendazole for Ascaris suum embryonic tubulin were 1.9 x 10-8 and 6.5 x 10-8 molar while those for bovine brain tubulin were 7.3 x 10-6 and 1.7 x 10-5 molar, values 250 to 400 times greater, so that differential binding affinities between nematode and mammalian tubulin may explain the selective toxicity. Condition category: normal nutrient_topic: Mebendazole research collection; topical membership is not evidence of a direct clinical effect, and mebendazole is recorded separately from albendazole, from the benzimidazole class and from its own crystal forms. plain_language: The drug grips worm tubulin hundreds of times more tightly than ours, which is the usual explanation for why it is safe. organism: Nematode and cattle tissue_or_cell_type: Embryonic nematode tubulin and bovine brain tubulin experimental_model: Inhibition of tritiated colchicine binding to cytosolic tubulin from 8-day Ascaris suum embryos and from bovine brain limitations: The founding selectivity result. It measures embryonic tubulin; the study in this collection that measured intestinal tubulin found a far smaller difference. exposure: Mebendazole and fenbendazole compared on the two tubulins in the same assay evidence_span: {"source_cache": "artifacts/mebendazole-research/7388055.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7", "start_char": 0, "end_char": 1209, "text_sha256": "5613d7fb281b4fd39b17bfdbafaf0ea823fb63b928048a9dd112fb71bf4cd2b7"} [mbz-p7388055] Interaction of anthelmintic benzimidazoles with Ascaris suum embryonic tubulin. (1980). https://pubmed.ncbi.nlm.nih.gov/7388055/ DOI: 10.1016/0304-4165(80)90431-6
    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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