PDBsum entry 4m76

Cell adhesion

PDB id: 4m76

Contents

Protein chains

296 a.a.

179 a.a.

Metals

_NI ×2

Waters ×33

PDB id:

4m76

Name:

Cell adhesion

Title:

Integrin i domain of complement receptor 3 in complex with c3d

Structure:

Complement c3. Chain: a. Fragment: unp residues 994-1288. Synonym: c3 and pzp-like alpha-2-macroglobulin domain-containing protein 1, complement c3 beta chain, complement c3 alpha chain, c3a anaphylatoxin, acylation stimulating protein, asp, c3adesarg, complement c3b alpha' chain, complement c3c alpha' chain fragment 1, complement c3dg fragment, complement c3g fragment, complement c3d fragment, complement c3f fragment, complement c3c alpha' chain

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: c3, cpamd1. Expressed in: escherichia coli. Expression_system_taxid: 469008. Gene: cd11b, cr3a, itgam.

Resolution:

2.80Å R-factor: 0.198 R-free: 0.242

Authors:

G.Bajic,L.Yatime,T.Vorup-Jensen,G.R.Andersen

Key ref:

G.Bajic et al. (2013). Structural insight on the recognition of surface-bound opsonins by the integrin I domain of complement receptor 3. Proc Natl Acad Sci U S A, 110, 16426-16431. PubMed id: 24065820 DOI: 10.1073/pnas.1311261110

Date:

12-Aug-13 Release date: 02-Oct-13

Protein chain

P01024  (CO3_HUMAN) -  Complement C3 from Homo sapiens

Seq: 1663 a.a.

Struc: 296 a.a.*

Protein chain

P11215  (ITAM_HUMAN) -  Integrin alpha-M from Homo sapiens

Seq: 1152 a.a.

Struc: 179 a.a.

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1073/pnas.1311261110

Proc Natl Acad Sci U S A 110:16426-16431 (2013)

PubMed id: 24065820

Structural insight on the recognition of surface-bound opsonins by the integrin I domain of complement receptor 3.

G.Bajic, L.Yatime, R.B.Sim, T.Vorup-Jensen, G.R.Andersen.

ABSTRACT

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.