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| Title | Allosteric regulation of fibronectin binding by the anti-β1 integrin antibody TS2/16. |
|---|---|
| Journal, issue, pages | PNAS Nexus, Vol. 5, Issue 3, Page pgag044, Year 2026 |
| Publish date | Feb 24, 2026 |
Authors | Jienyu Ding / Dalia A Fantini / Dirk Dedden / Stephanie Schumacher / Christian Biertümpfel / Naoko Mizuno / ![]() |
| PubMed Abstract | The monoclonal antibody (mAb) TS2/16 stabilizes the active conformation of β1 integrin, enhancing its adhesive capacity on the cell surface. However, the molecular mechanism by which TS2/16 ...The monoclonal antibody (mAb) TS2/16 stabilizes the active conformation of β1 integrin, enhancing its adhesive capacity on the cell surface. However, the molecular mechanism by which TS2/16 modulates integrin affinity for extracellular ligands remains unclear. Using endogenous full-length α5β1 integrin purified from human placenta, we determined the structure of integrin α5β1 with fibronectin up to 2.61-Å resolution in the absence of TS2/16, capturing the active form without its aid, and performed comparative B-factor-based analysis and CABS-Flex simulation with and without TS2/16. Despite no global conformational differences, we found that TS2/16 interacts with α2 helix of the integrin β1 subunit and contacts the C-terminus of α3 helix, leading to a localized decrease in B factor. This interaction allosterically alters the dynamics of α2-α3 loop despite not being in direct contact with TS2/16. Notably, this loop directly engages fibronectin, and its dynamic change underlies the enhanced ligand-binding affinity and explains increased cell adhesion observed with TS2/16. These findings reveal an allosteric mechanism of integrin regulation by TS2/16 and offer insights for the rational design of therapeutic antibodies targeting integrin-mediated adhesion in pathological contexts such as inflammation and cancer. |
External links | PNAS Nexus / PubMed:41809771 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 2.61 Å |
| Structure data | EMDB-71324, PDB-9p6s: |
| Chemicals | ![]() ChemComp-MN: ![]() ChemComp-NAG: ![]() ChemComp-HOH: |
| Source |
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Keywords | CELL ADHESION / a5b1 integrin / fibronectin / extracellular matrix / focal adhesion / single-particle |
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homo sapiens (human)
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