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PDBsum entry 4m76
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Cell adhesion
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PDB id
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4m76
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References listed in PDB file
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Key reference
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Title
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Structural insight on the recognition of surface-Bound opsonins by the integrin i domain of complement receptor 3.
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Authors
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G.Bajic,
L.Yatime,
R.B.Sim,
T.Vorup-Jensen,
G.R.Andersen.
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Ref.
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Proc Natl Acad Sci U S A, 2013,
110,
16426-16431.
[DOI no: ]
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PubMed id
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Abstract
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Complement receptors (CRs), expressed notably on myeloid and lymphoid cells,
play an essential function in the elimination of complement-opsonized pathogens
and apoptotic/necrotic cells. In addition, these receptors are crucial for the
cross-talk between the innate and adaptive branches of the immune system. CR3
(also known as Mac-1, integrin αMβ2, or CD11b/CD18) is expressed on all
macrophages and recognizes iC3b on complement-opsonized objects, enabling their
phagocytosis. We demonstrate that the C3d moiety of iC3b harbors the binding
site for the CR3 αI domain, and our structure of the C3d:αI domain complex
rationalizes the CR3 selectivity for iC3b. Based on extensive structural
analysis, we suggest that the choice between a ligand glutamate or aspartate for
coordination of a receptor metal ion-dependent adhesion site-bound metal ion is
governed by the secondary structure of the ligand. Comparison of our structure
to the CR2:C3d complex and the in vitro formation of a stable CR3:C3d:CR2
complex suggests a molecular mechanism for the hand-over of CR3-bound immune
complexes from macrophages to CR2-presenting cells in lymph nodes.
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