Download MendeleyThree cryo-EM structures of complement C3d-bound alpha M beta 2 reveal an unexpected layer of dynamics for alpha I-containing integrin receptors.
Lorentzen, J., Fruergaard, M.U., Lukacsi, S., Jorgensen, M.H., van Veghel, T.L.G., Jensen, R.K., Pietrzak-Lichwa, K.J., Bajtay, Z., Horejsi, V., Flygaard, R.K., Vorselen, D., Mortensen, S.A., Andersen, G.R.(2026) Sci Adv 12: eaea7241-eaea7241
- PubMed: 42102216 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1126/sciadv.aea7241
- Primary Citation Related Structures:
9GMU, 9HLL, 9RM9, 9RMA, 9T3Y, 9T5V, 9T5W, 9T5Z - PubMed Abstract:
Integrins are heterodimeric membrane proteins acting as mechanosensing receptors. Nine human α-subunits contain a ligand binding αI domain, but how ligands activate αI integrins are not understood. We present cryo-EM structures of the αI integrin α M β 2 in complex with the C3d ligand. The ligand-bound αI domain appears to have two major opposite orientations relative to the β 2 subunit. Ligand binding induces an ordered conformation of the α M internal ligand region that is tightly packed between the α M β-propeller and the β 2 βI-domain. Recognition of the internal ligand induces an open βI conformation practically identical to that of ligand-bound αI-less integrins confirming that ligand binding and signaling are coupled by a universal mechanism across all integrins. Integration of our findings with prior data allows us to propose a model for C3dg/iC3b-bound α M β 2 in the phagocytotic cup and outline mechanistic models for external ligand-induced activation of α M β 2 .
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, DK8000, Denmark.
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