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PDBsum entry 1zop
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Cell adhesion
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PDB id
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1zop
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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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The role of the divalent cation in the structure of the i domain from the cd11a/cd18 integrin.
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Authors
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A.Qu,
D.J.Leahy.
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Ref.
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Structure, 1996,
4,
931-942.
[DOI no: ]
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PubMed id
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Abstract
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BACKGROUND: The integrin family of cell-surface receptors mediates a wide
variety of cell-cell and cell-extracellular matrix interactions. Integrin-ligand
interactions are invariably dependent on the presence of divalent cations, and a
subset of integrins contain a approximately 200 amino acid inserted (I) domain
that is important for ligand binding activity and contains a single divalent
cation binding site. Many integrins are believed to respond to stimuli by
undergoing a conformational change that increases their affinity for ligand, and
there is a clear difference between two crystal structures of the CD11b I domain
with different divalent cations (magnesium and manganese) bound. In addition to
the different bound cation, a 'ligand mimetic' crystal lattice interaction in
the CD11b I domain structure with bound magnesium has led to the interpretation
that the different CD11b I domain structures represent different affinity states
of I domains. The influence of the bound cation on I domain structure and
function remains incompletely understood, however. The crystal structure of the
CD11a I domain bound to manganese is known. We therefore set out to determine
whether this structure changes when the metal ion is altered or removed.
RESULTS: We report here the crystal structures of the CD11a I domain determined
in the absence of bound metal ion and with bound magnesium ion. No major
structural rearrangements are observed in the metal-binding site of the CD11a I
domain in the absence or presence of bound manganese ion. The structures of the
CD11a I domain with magnesium or manganese bound are extremely similar.
CONCLUSIONS: The conformation of the CD11a I domain is not altered by changes in
metal ion binding. The cation-dependence of ligand binding thus indicates that
the metal ion is either involved in direct interaction with ligand or required
to promote a favorable quaternary arrangement of the integrin.
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Figure 2.
Figure 2. The overall fold of the CD11a I domain. (a) Ribbon
diagram of CD11a-I(EDTA). The side chains of Ser139, Ser141, and
Asp239 are shown in green with red oxygen atoms. The N and C
termini, the β strands, and the α helical segments are
labeled. (b) Stereo view of superimposed Cα backbones of
CD11a-I(EDTA) (solid blue line) and CD11a-I(Mn) (dashed red
line). The N and C termini are labeled and every tenth residue
of CD11a-I(EDTA) is indicated by a solid circle. Figure 2.
The overall fold of the CD11a I domain. (a) Ribbon diagram of
CD11a-I(EDTA). The side chains of Ser139, Ser141, and Asp239 are
shown in green with red oxygen atoms. The N and C termini, the
β strands, and the α helical segments are labeled. (b) Stereo
view of superimposed Cα backbones of CD11a-I(EDTA) (solid blue
line) and CD11a-I(Mn) (dashed red line). The N and C termini are
labeled and every tenth residue of CD11a-I(EDTA) is indicated by
a solid circle. (Figure made with the program MOLSCRIPT
[[4]41].)
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Figure 5.
Figure 5. The position of the α7 helices. (a) Deviation of the
α7 helices of CD11a-I(EDTA) and CD11a-I(Mn) following
superposition. A superposition of Cα backbone traces of
CD11a-I(EDTA) and CD11a-I(Mn) is shown. The α7 helix of
CD11a-I(EDTA) is shown in blue, and the α7 helix of
CD11a-I(Mn) is shown in red. (b) Dimer interaction observed in
CD11a-I(Mn) and CD11a-I(Mg) crystal structures. The structures
shown constitute the contents of one asymmetric unit. The α7
helices of each molecule are labeled. In both figures the
manganese ions are depicted as magenta spheres. Figure 5. The
position of the α7 helices. (a) Deviation of the α7 helices of
CD11a-I(EDTA) and CD11a-I(Mn) following superposition. A
superposition of Cα backbone traces of CD11a-I(EDTA) and
CD11a-I(Mn) is shown. The α7 helix of CD11a-I(EDTA) is shown in
blue, and the α7 helix of CD11a-I(Mn) is shown in red. (b)
Dimer interaction observed in CD11a-I(Mn) and CD11a-I(Mg)
crystal structures. The structures shown constitute the contents
of one asymmetric unit. The α7 helices of each molecule are
labeled. In both figures the manganese ions are depicted as
magenta spheres. (Figures made with the program SETOR [[3]43].)
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The above figures are
reprinted
by permission from Cell Press:
Structure
(1996,
4,
931-942)
copyright 1996.
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Secondary reference #1
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Title
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Crystal structure of the I-Domain from the cd11a/cd18 (lfa-1, Alpha l beta 2) integrin.
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Authors
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A.Qu,
D.J.Leahy.
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Ref.
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Proc Natl Acad Sci U S A, 1995,
92,
10277-10281.
[DOI no: ]
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PubMed id
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