Binding affinity of a glucan for its receptor

Where it participates (unsigned role)

1. CR3 serves as the leukocyte beta-glucan receptor through a cation-independent lectin site located C-terminal to the I-domain of CD11b that contains the binding sites for iC3b, ICAM-1 and fibrinogen, a 10-kilodalton soluble zymosan polysaccharide consisting largely of mannose and approximately 5% glucose bound with high affinity of 6.7 x 10(-8) M, binding was blocked not only by pure beta-glucans from yeast, mushroom, seaweed or barley but also by N-acetyl-D-glucosamine and alpha- or beta-methylmannoside and alpha- or beta-methylglucoside, and its sugar specificity is broader than originally appreciated.

   The lectin site of CD11b C-terminal to the I-domain → Beta-glucan source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/glucan-research/8558003.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "00a0fef65e91375066fe9920200032466aec1c0d85bf548d53f64c3d384106b7", "start_char": 0, "end_char": 1936, "text_sha256": "00a0fef65e91375066fe9920200032466aec1c0d85bf548d53f64c3d384106b7"}

   experimental_model

   Flow cytometry with labelled soluble polysaccharides, CR3 and CR4 chimeras, and a panel of domain-specific antibodies

   exposure

   Labelled beta-glucans from yeast, mushroom, seaweed and barley, and a 10-kilodalton soluble zymosan polysaccharide

   limitations

   Binding and inhibition rather than function. The highest-affinity ligand measured was not a pure beta-glucan but a mannose-rich zymosan polysaccharide, and the sugar specificity proved broader than beta-glucan alone.

   nutrient_topic

   Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. · Beta-glucan

   organism

   Human

   plain_language

   The complement receptor grips sugars at a second site, separate from the one that grips the complement fragment.

   primary_references

   [bg-p8558003] Analysis of the sugar specificity and molecular location of the beta-glucan-binding lectin site of complement receptor type 3 (CD11b/CD18). (1996). https://pubmed.ncbi.nlm.nih.gov/8558003/ DOI: 10.4049/jimmunol.156.3.1235

   tissue_or_cell_type

   Leukocytes

   Beta-glucan: a structural family rather than an agent, what decides whether a bound glucan actually signals, the complement route that a cereal and a yeast preparation share, and the unequal human evidence behind each (2026-09-22) · lines 203–214

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Flow cytometry with labelled soluble polysaccharides, CR3 and CR4 chimeras, and a panel of domain-specific antibodies · source_derived_draft · unverified_draft

   ### bg-cr3-has-a-lectin-site CR3 serves as the leukocyte beta-glucan receptor through a cation-independent lectin site located C-terminal to the I-domain of CD11b that contains the binding sites for iC3b, ICAM-1 and fibrinogen, a 10-kilodalton soluble zymosan polysaccharide consisting largely of mannose and approximately 5% glucose bound with high affinity of 6.7 x 10(-8) M, binding was blocked not only by pure beta-glucans from yeast, mushroom, seaweed or barley but also by N-acetyl-D-glucosamine and alpha- or beta-methylmannoside and alpha- or beta-methylglucoside, and its sugar specificity is broader than originally appreciated. Condition category: normal nutrient_topic: Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. plain_language: The complement receptor grips sugars at a second site, separate from the one that grips the complement fragment. organism: Human tissue_or_cell_type: Leukocytes experimental_model: Flow cytometry with labelled soluble polysaccharides, CR3 and CR4 chimeras, and a panel of domain-specific antibodies limitations: Binding and inhibition rather than function. The highest-affinity ligand measured was not a pure beta-glucan but a mannose-rich zymosan polysaccharide, and the sugar specificity proved broader than beta-glucan alone. exposure: Labelled beta-glucans from yeast, mushroom, seaweed and barley, and a 10-kilodalton soluble zymosan polysaccharide evidence_span: {"source_cache": "artifacts/glucan-research/8558003.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "00a0fef65e91375066fe9920200032466aec1c0d85bf548d53f64c3d384106b7", "start_char": 0, "end_char": 1936, "text_sha256": "00a0fef65e91375066fe9920200032466aec1c0d85bf548d53f64c3d384106b7"} [bg-p8558003] Analysis of the sugar specificity and molecular location of the beta-glucan-binding lectin site of complement receptor type 3 (CD11b/CD18). (1996). https://pubmed.ncbi.nlm.nih.gov/8558003/ DOI: 10.4049/jimmunol.156.3.1235

   Complete structured claim and evidence

2. Laminarin is a (1->3, 1->6)-beta-glucan that is widely reported to be a Dectin-1 antagonist, however there are reports that laminarin is also a Dectin-1 agonist, and of five preparations from three commercial sources all contained laminarin although their molecular mass varied considerably from 4400 to 34,400 daltons, all were bound by recombinant human and mouse Dectin-1 but the affinity varied considerably and binding affinity did not correlate with Dectin-1 agonism, antagonism or potency, two laminarins were Dectin-1 antagonists and two were agonists, and the remaining laminarin was an antagonist but became an agonist when the low molecular weight moieties were removed.

   Purity of a commercial glucan preparation → Ability of a bound glucan to produce a receptor signal source_derived_draftungraded
   Experimental context and source evidence

   availability_state

   biomarker_context Imported condition classification; unverified.

   evidence_span

   {"source_cache": "artifacts/glucan-research/29246954.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5afc1ddc8e49971759dcdc432cedb4c22cad267cace1e3909dd577c8ebb9eaa6", "start_char": 0, "end_char": 1760, "text_sha256": "5afc1ddc8e49971759dcdc432cedb4c22cad267cace1e3909dd577c8ebb9eaa6"}

   experimental_model

   Physical, structural, purity, binding and functional comparison of five commercial laminarin preparations from three suppliers

   exposure

   Five laminarin preparations of molecular mass 4400 to 34,400 daltons, before and after extensive dialysis

   limitations

   Five preparations of one named natural product. Removing low molecular weight contaminants explained the behaviour of one preparation and not the others, so purity is one cause of the variation rather than the whole of it.

   nutrient_topic

   Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. · Beta-glucan

   organism

   Human and mouse cells

   plain_language

   Five bottles with the same name on the label: two blocked the receptor, two switched it on, and cleaning up a fifth flipped it.

   primary_references

   [bg-p29246954] Immunoregulatory Activity of the Natural Product Laminarin Varies Widely as a Result of Its Physical Properties. (2018). https://pubmed.ncbi.nlm.nih.gov/29246954/ DOI: 10.4049/jimmunol.1701258

   tissue_or_cell_type

   Recombinant receptor and primary cells

   trigger_kind

   biomarker_context Imported condition classification; unverified.

   Beta-glucan: a structural family rather than an agent, what decides whether a bound glucan actually signals, the complement route that a cereal and a yeast preparation share, and the unequal human evidence behind each (2026-09-22) · lines 164–175

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Physical, structural, purity, binding and functional comparison of five commercial laminarin preparations from three suppliers · source_derived_draft · unverified_draft

   ### bg-same-name-opposite-activity Laminarin is a (1->3, 1->6)-beta-glucan that is widely reported to be a Dectin-1 antagonist, however there are reports that laminarin is also a Dectin-1 agonist, and of five preparations from three commercial sources all contained laminarin although their molecular mass varied considerably from 4400 to 34,400 daltons, all were bound by recombinant human and mouse Dectin-1 but the affinity varied considerably and binding affinity did not correlate with Dectin-1 agonism, antagonism or potency, two laminarins were Dectin-1 antagonists and two were agonists, and the remaining laminarin was an antagonist but became an agonist when the low molecular weight moieties were removed. Condition category: biomarker_context nutrient_topic: Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. plain_language: Five bottles with the same name on the label: two blocked the receptor, two switched it on, and cleaning up a fifth flipped it. organism: Human and mouse cells tissue_or_cell_type: Recombinant receptor and primary cells experimental_model: Physical, structural, purity, binding and functional comparison of five commercial laminarin preparations from three suppliers limitations: Five preparations of one named natural product. Removing low molecular weight contaminants explained the behaviour of one preparation and not the others, so purity is one cause of the variation rather than the whole of it. exposure: Five laminarin preparations of molecular mass 4400 to 34,400 daltons, before and after extensive dialysis evidence_span: {"source_cache": "artifacts/glucan-research/29246954.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5afc1ddc8e49971759dcdc432cedb4c22cad267cace1e3909dd577c8ebb9eaa6", "start_char": 0, "end_char": 1760, "text_sha256": "5afc1ddc8e49971759dcdc432cedb4c22cad267cace1e3909dd577c8ebb9eaa6"} [bg-p29246954] Immunoregulatory Activity of the Natural Product Laminarin Varies Widely as a Result of Its Physical Properties. (2018). https://pubmed.ncbi.nlm.nih.gov/29246954/ DOI: 10.4049/jimmunol.1701258

   Complete structured claim and evidence

3. Beta-glucans can adopt solution structures ranging from random coil to insoluble fibre due to tertiary helical and quaternary structure, and despite similar affinity for Dectin-1 the ability of glucans to induce Dectin-1A-mediated signalling correlates with degree of structure, with glucan denaturation experiments showing that glucan structure determines agonistic potential but not receptor binding affinity, while fluorescence measurements provided direct evidence of ligation-induced Dectin-1A aggregation which positively correlated with increasing glucan structure content.

   Solution conformation of a glucan, from random coil to insoluble fibre → Ability of a bound glucan to produce a receptor signal source_derived_draftungraded
   Experimental context and source evidence

   availability_state

   biomarker_context Imported condition classification; unverified.

   evidence_span

   {"source_cache": "artifacts/glucan-research/37515324.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "c5c602f96f0ff319650a47cb53c772df30c0dc267f6e82c46ae51bb5285b6d3f", "start_char": 0, "end_char": 1658, "text_sha256": "c5c602f96f0ff319650a47cb53c772df30c0dc267f6e82c46ae51bb5285b6d3f"}

   experimental_model

   Glucan denaturation, fluorescence measurement of receptor aggregation and diffusion, and fungal particle contact sites

   exposure

   Fungal beta-glucans of low, medium and high molecular weight differing in helical structure content, before and after denaturation

   limitations

   A single-receptor-isoform study using defined glucan conformations. The aggregates observed were small, a few engaged receptors rather than synapse-scale structures.

   nutrient_topic

   Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. · Beta-glucan

   organism

   Human receptor in cultured cells

   plain_language

   What decides whether the receptor fires is the shape the sugar holds in solution, not how tightly it sticks and not whether it dissolves.

   primary_references

   [bg-p37515324] Dectin-1 multimerization and signaling depends on fungal β-glucan structure and exposure. (2023). https://pubmed.ncbi.nlm.nih.gov/37515324/ DOI: 10.1016/j.bpj.2023.07.021

   tissue_or_cell_type

   Dectin-1A-expressing cells and Candida cell wall

   trigger_kind

   biomarker_context Imported condition classification; unverified.

   Beta-glucan: a structural family rather than an agent, what decides whether a bound glucan actually signals, the complement route that a cereal and a yeast preparation share, and the unequal human evidence behind each (2026-09-22) · lines 151–162

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Glucan denaturation, fluorescence measurement of receptor aggregation and diffusion, and fungal particle contact sites · source_derived_draft · unverified_draft

   ### bg-structure-not-solubility-signals Beta-glucans can adopt solution structures ranging from random coil to insoluble fibre due to tertiary helical and quaternary structure, and despite similar affinity for Dectin-1 the ability of glucans to induce Dectin-1A-mediated signalling correlates with degree of structure, with glucan denaturation experiments showing that glucan structure determines agonistic potential but not receptor binding affinity, while fluorescence measurements provided direct evidence of ligation-induced Dectin-1A aggregation which positively correlated with increasing glucan structure content. Condition category: biomarker_context nutrient_topic: Beta-glucan research collection; topical membership is not evidence of a direct clinical effect, and each preparation is recorded as its own entity with no family link joining any pair. plain_language: What decides whether the receptor fires is the shape the sugar holds in solution, not how tightly it sticks and not whether it dissolves. organism: Human receptor in cultured cells tissue_or_cell_type: Dectin-1A-expressing cells and Candida cell wall experimental_model: Glucan denaturation, fluorescence measurement of receptor aggregation and diffusion, and fungal particle contact sites limitations: A single-receptor-isoform study using defined glucan conformations. The aggregates observed were small, a few engaged receptors rather than synapse-scale structures. exposure: Fungal beta-glucans of low, medium and high molecular weight differing in helical structure content, before and after denaturation evidence_span: {"source_cache": "artifacts/glucan-research/37515324.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "c5c602f96f0ff319650a47cb53c772df30c0dc267f6e82c46ae51bb5285b6d3f", "start_char": 0, "end_char": 1658, "text_sha256": "c5c602f96f0ff319650a47cb53c772df30c0dc267f6e82c46ae51bb5285b6d3f"} [bg-p37515324] Dectin-1 multimerization and signaling depends on fungal β-glucan structure and exposure. (2023). https://pubmed.ncbi.nlm.nih.gov/37515324/ DOI: 10.1016/j.bpj.2023.07.021

   Complete structured claim and evidence