PDBsum entry 1e4j

Immune system

PDB id: 1e4j

Contents

Protein chain

171 a.a. *

Waters ×67

* Residue conservation analysis

PDB id:

1e4j

Name:

Immune system

Title:

Crystal structure of the soluble human fc-gamma receptor iii

Structure:

Low affinity immunoglobulin gamma fc receptor iii. Chain: a. Fragment: extracellular domain. Synonym: cd16. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Cell: leukocyte. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.50Å R-factor: 0.195 R-free: 0.261

Authors:

P.Sondermann,R.Huber,U.Jacob

Key ref:

P.Sondermann et al. (2000). The 3.2-A crystal structure of the human IgG1 Fc fragment-Fc gammaRIII complex. Nature, 406, 267-273. PubMed id: 10917521 DOI: 10.1038/35018508

Date:

07-Jul-00 Release date: 04-Aug-00

Protein chain

O75015  (FCG3B_HUMAN) -  Low affinity immunoglobulin gamma Fc region receptor III-B from Homo sapiens

Seq: 233 a.a.

Struc: 171 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1038/35018508

Nature 406:267-273 (2000)

PubMed id: 10917521

The 3.2-A crystal structure of the human IgG1 Fc fragment-Fc gammaRIII complex.

P.Sondermann, R.Huber, V.Oosthuizen, U.Jacob.

ABSTRACT

The immune response depends on the binding of opsonized antigens to cellular Fc receptors and the subsequent initiation of various cellular effector functions of the immune system. Here we describe the crystal structures of a soluble Fc gamma receptor (sFc gammaRIII, CD16), an Fc fragment from human IgG1 (hFc1) and their complex. In the 1:1 complex the receptor binds to the two halves of the Fc fragment in contact with residues of the C gamma2 domains and the hinge region. Upon complex formation the angle between the two sFc gammaRIII domains increases significantly and the Fc fragment opens asymmetrically. The high degree of amino acid conservation between sFc gammaRIII and other Fc receptors, and similarly between hFc1 and related immunoglobulins, suggest similar structures and modes of association. Thus the described structure is a model for immune complex recognition and helps to explain the vastly differing affinities of other Fc gammaR-IgG complexes and the Fc epsilonRI alpha-IgE complex.

Selected figure(s)

Figure 1.
Figure 1: The overall structure of the sFc bold gamma-RIII-hFc1 complex. a, Stereo ribbon representation with the dimer axis of hFc1 (red and blue) orientated vertically. The 'proline sandwich' consisting of Pro 329 of the C 2-A domain and Trp 87 and Trp 110 of sFc RIII (green) is shown in ball and stick together with the carbohydrate residues of the Fc fragment and the interchain disulphide bridge (yellow) of the Cys 229 residues. The potential N-glycosylation sites in sFc RIII are shown as cyan balls. b, Side view of the complex obtained by a rotation of 90° around the y axis. Unless indicated, all figures were produced with the programs MOLSCRIPT46 and RASTER3D^47.

Figure 2.
Figure 2: Superposition of the complexed components with the free structures (C alpha-trace). a, sFc RIII in complexed form (cyan) was superimposed with a least square algorithm using the C atoms of the first domain onto the structure of sFc RIII obtained from sFc RIII crystals (magenta). Trp 95 and Tyr 14 which form a new hydrogen bond upon complex formation are shown in ball and stick representation b, Overlay of the hFc1 structures obtained from the complex (cyan) and from hFc1 crystals (magenta). For the superposition the C atoms of both C 3 domains were used. The orientation of the structures is the same as in Fig. 1a.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2000, 406, 267-273) copyright 2000.

Figures were selected by an automated process.