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PDBsum entry 1h9v
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Immune system, membrane protein
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PDB id
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1h9v
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Molecular basis for immune complex recognition: a comparison of fc-Receptor structures.
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Authors
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P.Sondermann,
J.Kaiser,
U.Jacob.
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Ref.
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J Mol Biol, 2001,
309,
737-749.
[DOI no: ]
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PubMed id
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Abstract
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Once antigen is opsonised by IgG it is removed from the circulation by
Fcgamma-receptor expressing cells. Fcgamma-receptors are type I transmembrane
molecules that carry extracellular parts consisting of two or three
immunoglobulin domains. Previously solved structures of Fc-receptors reveal that
the N-terminal two Ig-like domains are arranged in a steep angle forming a
heart-shaped structure. The crystal structure of the
FcgammaRIII/hIgG1-Fc-fragment demonstrated that the Fc-fragment is recognised
through loops of the C-terminal receptor domain of the FcgammaRIII. As the
overall structure of the FcRs and their Ig ligands are very similar we modelled
the Ig complexes with FcgammaRI, FcgammaRII and FcepsilonRIalpha based on the
FcgammaRIII/hIgG1-Fc-fragment structure. The obtained models are consistent with
the observed biochemical data and may explain the observed specificity and
affinities.
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Figure 2.
Figure 2. Stereo ribbon representation of the sFcgRIII structure with residues relevant for IgG binding. The amino
acid residues of FcgRIII which contact IgG are shown in ball-and-stick representation. Residues contacting the Cg2-A
domain are coloured magenta and those contacting the Cg2-B domain green. Potential glycosylation sites are depicted
as cyan balls and the disulphide bridges in yellow. The termini are labelled and the b-strands are numbered consecu-
tively for the N-terminal domain in black and for the C-terminal domain in blue. The orientation is the same as
Figure 1 (upper left), except that it is rotated by approximately 180 ° around the axis perpendicular to the plane of
the paper. The Figure was created using MOLSCRIPT
37
and RASTER3D.
38
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Figure 5.
Figure 5. Surface analysis of the FcR structures. A surface analysis was performed using the program GRASP
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with the crystal structures of FcgRIIa, FcgRIIb, FcgRIII and FceRIa as well as the modelled FcgRI. The colour coding
spans from hydrophobic (green) to hydrophilic (red) with potential glycosylation sites indicated as blue balls. The
viewpoint is indicated with respect to the front view, which shows an identical orientation as in Figure 2. The IgG
binding site is surrounded by a black box in the FcgRIII molecule. The unique hydrophobic region on the N-terminal
domain of FcgRIII is circled.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2001,
309,
737-749)
copyright 2001.
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