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PDBsum entry 1t0p
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Immune system
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PDB id
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1t0p
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References listed in PDB file
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Key reference
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Title
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An atomic resolution view of icam recognition in a complex between the binding domains of icam-3 and integrin alphalbeta2.
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Authors
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G.Song,
Y.Yang,
J.H.Liu,
J.M.Casasnovas,
M.Shimaoka,
T.A.Springer,
J.H.Wang.
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Ref.
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Proc Natl Acad Sci U S A, 2005,
102,
3366-3371.
[DOI no: ]
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PubMed id
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Abstract
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Within the Ig superfamily (IgSF), intercellular adhesion molecules (ICAMs) form
a subfamily that binds the leukocyte integrin alphaLbeta2. We report a
1.65-A-resolution crystal structure of the ICAM-3 N-terminal domain (D1) in
complex with the inserted domain, the ligand-binding domain of alphaLbeta2. This
high-resolution structure and comparisons among ICAM subfamily members establish
that the binding of ICAM-3 D1 onto the inserted domain represents a common
docking mode for ICAM subfamily members. The markedly different off-rates of
ICAM-1, -2, and -3 appear to be determined by the hydrophobicity of residues
that surround a metal coordination bond in the alphaLbeta2-binding interfaces.
Variation in composition of glycans on the periphery of the interfaces
influences on-rate.
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Figure 3.
Fig. 3. The ICAM-3/  [L]  [2] binding interface.
(A) The interface residues are shown in light cyan and light
gold for ICAM-3 and the I domain, respectively. The metal ion,
oxygens, and nitrogens are shown as magenta, red, and blue
spheres, respectively. Water molecules are shown as red spheres.
Metal coordination is shown by black dashed lines. Hydrogen
bonds and a salt bridge between Lys-42 in ICAM-3 and Glu-241 in
the I domain are represented by silver dashed lines. Residues
involved in the hydrophobic patch are colored in silver. For
clarity, MIDAS residues are omitted. (B) Structural elements
that stabilize the conformation of the CD loop of ICAM-3. The CD
and EF loops are colored in yellow and green, respectively. Only
relevant side chains are shown in this figure for clarity.
Hydrophobic, neutral hydrophilic, and basic residues are colored
in orange, cyan, and blue, respectively. The broken lines
represent hydrogen bonds, whereas the silver ball is a bound
water molecule. A was prepared with RIBBONS (43), and B was
prepared with SETOR (44).
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Figure 4.
Fig. 4. Surface representation of the binding faces of
ICAM-3 and -1. Negatively and positively charged residues are
colored red and blue, respectively. Hydrophobic and neutral
hydrophilic residues are colored white and yellow, respectively.
Some important residues are labeled. The binding footprints are
encircled with green dashed lines. Prepared with GRASP (45).
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