PDBsum entry 1ovz

Immune system

PDB id: 1ovz

Contents

Protein chains

193 a.a. *

181 a.a. *

Ligands

NAG-NAG

NAG ×3

TRS

* Residue conservation analysis

PDB id:

1ovz

Name:

Immune system

Title:

Crystal structure of human fcari

Structure:

Immunoglobulin alpha fc receptor. Chain: a, b. Fragment: ectodomain. Synonym: iga fc receptor, cd89 antigen. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: fcar or cd89. Expressed in: trichoplusia ni. Expression_system_taxid: 7111.

Biol. unit:

Tetramer (from PQS)

Resolution:

3.00Å R-factor: 0.235 R-free: 0.292

Authors:

A.B.Herr,E.R.Ballister,P.J.Bjorkman

Key ref:

A.B.Herr et al. (2003). Insights into IgA-mediated immune responses from the crystal structures of human FcalphaRI and its complex with IgA1-Fc. Nature, 423, 614-620. PubMed id: 12768205 DOI: 10.1038/nature01685

Date:

27-Mar-03 Release date: 27-May-03

Protein chain

P24071  (FCAR_HUMAN) -  Immunoglobulin alpha Fc receptor from Homo sapiens

Seq: 287 a.a.

Struc: 193 a.a.*

Protein chain

P24071  (FCAR_HUMAN) -  Immunoglobulin alpha Fc receptor from Homo sapiens

Seq: 287 a.a.

Struc: 181 a.a.

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

DOI no: 10.1038/nature01685

Nature 423:614-620 (2003)

PubMed id: 12768205

Insights into IgA-mediated immune responses from the crystal structures of human FcalphaRI and its complex with IgA1-Fc.

A.B.Herr, E.R.Ballister, P.J.Bjorkman.

ABSTRACT

Immunoglobulin-alpha (IgA)-bound antigens induce immune effector responses by activating the IgA-specific receptor FcalphaRI (CD89) on immune cells. Here we present crystal structures of human FcalphaRI alone and in a complex with the Fc region of IgA1 (Fcalpha). FcalphaRI has two immunoglobulin-like domains that are oriented at approximately right angles to each other. Fcalpha resembles the Fcs of immunoglobulins IgG and IgE, but has differently located interchain disulphide bonds and external rather than interdomain N-linked carbohydrates. Unlike 1:1 FcgammaRIII:IgG and Fc epsilon RI:IgE complexes, two FcalphaRI molecules bind each Fcalpha dimer, one at each Calpha2-Calpha3 junction. The FcalphaRI-binding site on IgA1 overlaps the reported polymeric immunoglobulin receptor (pIgR)-binding site, which might explain why secretory IgA cannot initiate phagocytosis or bind to FcalphaRI-expressing cells in the absence of an integrin co-receptor.

Selected figure(s)

Figure 2.
Figure 2: Fc alpha-structure. a, Ribbon diagrams showing front (left) and side (right) views of Fc (top) and Fc (bottom)33. Disulphide bonds are shown in yellow and carbohydrate residues are shown in ball-and-stick representation. b, Topology diagram of Fc . -Strands are blue or magenta, 3[10] and -helices are light blue and disulphides are yellow. The proposed C241 -C241 disulphide bond (not present in our construct) is shown as a dashed yellow line. Blue and magenta dots show residues that contact Fc RI.

Figure 4.
Figure 4: Fc alpha-RI:Fc alpha-interface. Stereoviews of residues at the Fc RI:Fc interface (defined as residues with any non-hydrogen atom within 4 Å of the partner domain). Potential hydrogen bonds are shown as black dotted lines. Residues are colour-coded according to protein (a), the chemical character of their side chains (b), or their effects on binding affinity when substituted^13,14,26 -28 (c).

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2003, 423, 614-620) copyright 2003.

Figures were selected by an automated process.