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PDBsum entry 1a78
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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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Soluble beta-Galactosyl-Binding lectin (galectin) from toad ovary: crystallographic studies of two protein-Sugar complexes.
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Authors
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M.A.Bianchet,
H.Ahmed,
G.R.Vasta,
L.M.Amzel.
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Ref.
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Proteins, 2000,
40,
378-388.
[DOI no: ]
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
percentage match of
82%.
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Abstract
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Galectin-1, S-type beta-galactosyl-binding lectins present in vertebrate and
invertebrate species, are dimeric proteins that participate in cellular
adhesion, activation, growth regulation, and apoptosis. Two high-resolution
crystal structures of B. arenarum galectin-1 in complex with two related
carbohydrates, LacNAc and TDG, show that the topologically equivalent hydroxyl
groups in the two disaccharides exhibit identical patterns of interaction with
the protein. Groups that are not equivalent between the two sugars present in
the second moiety of the disaccharide, interact differently with the protein,
but use the same number and quality of interactions. The structures show
additional protein-carbohydrate interactions not present in previously reported
lectin-lactose complexes. These contacts provide an explanation for the enhanced
affinity of galectin-1 for TDG and LacNAc relative to lactose. Galectins are in
dimer-monomer equilibrium at physiological protein concentrations, suggesting
that this equilibrium may be involved in organ-specific regulation of activity.
Comparison of B. arenarum with other galectin-1 structures shows that among
different galectins there are significant changes in accessible surface area
buried upon dimer formation, providing a rationale for the variations observed
in the free-energies of dimerization. The structure of the B. arenarum
galectin-1 has a large cleft with a strong negative potential that connects the
two binding sites at the surface of the protein. Such a striking characteristic
suggests that this cleft is probably involved in interactions of the galectin
with other intra or extra-cellular proteins. Proteins 2000;40:378-388.
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Figure 4.
Figure 4. Thiogalactosamine bound to B. arenarum lectin
(monomer B). The relevant CRD residues and the hydrogen bonds
(dashed lines) to the sugar are shown. Carbon atoms are in
white, oxygen in red; sulfur in yellow; nitrogen in blue.
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Figure 5.
Figure 5. N-acetyllactosamine bound to B. arenarum lectin
(monomer B). The relevant CRD residues and the hydrogen bonds
(dashed lines) to the sugar are shown. The atoms are colored as
in Figure 4.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2000,
40,
378-388)
copyright 2000.
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