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PDBsum entry 1dr9
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Immune system
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PDB id
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1dr9
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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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Structure and dimerization of a soluble form of b7-1.
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Authors
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S.Ikemizu,
R.J.Gilbert,
J.A.Fennelly,
A.V.Collins,
K.Harlos,
E.Y.Jones,
D.I.Stuart,
S.J.Davis.
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Ref.
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Immunity, 2000,
12,
51-60.
[DOI no: ]
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PubMed id
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Abstract
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B7-1 (CD80) and B7-2 (CD86) are glycoproteins expressed on antigen-presenting
cells. The binding of these molecules to the T cell homodimers CD28 and CTLA-4
(CD152) generates costimulatory and inhibitory signals in T cells, respectively.
The crystal structure of the extracellular region of B7-1 (sB7-1), solved to 3 A
resolution, consists of a novel combination of two Ig-like domains, one
characteristic of adhesion molecules and the other previously seen only in
antigen receptors. In the crystal lattice, sB7-1 unexpectedly forms parallel,
2-fold rotationally symmetric homodimers. Analytical ultracentrifugation reveals
that sB7-1 also dimerizes in solution. The structural data suggest a mechanism
whereby the avidity-enhanced binding of B7-1 and CTLA-4 homodimers, along with
the relatively high affinity of these interactions, favors the formation of very
stable inhibitory signaling complexes.
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Figure 4.
Figure 4. Structure of the sB7-1 Homodimer Observed in the
Crystal Lattice(A) Two orthogonal views of the GRASP surface of
the homodimer showing the location of residues whose mutation to
alanine disrupts (magenta) or has no effect (cyan) on binding.
Putative N-glycosylation sites are colored green.(B) The GRASP
surfaces of amino acids involved in forming the dimer are
colored red. The view is identical to the right-hand panel in
(A) but with the front copy of sB7-1 removed.(C) Details of the
residues at the dimer interface are shown in ball-and-stick
format viewed as in the left-hand panel of (A).(D) The homodimer
is shown with either oligomannose, bi-, or triantennary
N-glycans modeled at each of the potential glycosylation sites.
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Figure 6.
Figure 6. Evolutionary Relationships of the IgSF
Constant-like DomainsThe parts of the lineage colored blue are
proposed to have generated cell adhesion and cell–cell
recognition molecules, whereas the red section produced
components of the adaptive immune response. CD2 is used to
represent the C2/I-set.
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The above figures are
reprinted
by permission from Cell Press:
Immunity
(2000,
12,
51-60)
copyright 2000.
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