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PDBsum entry 1buu
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Sugar binding protein
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PDB id
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1buu
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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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Ca2+-Dependent structural changes in c-Type mannose-Binding proteins.
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Authors
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K.K.Ng,
S.Park-Snyder,
W.I.Weis.
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Ref.
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Biochemistry, 1998,
37,
17965-17976.
[DOI no: ]
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PubMed id
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Abstract
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C-type animal lectins are a diverse family of proteins which mediate
cell-surface carbohydrate-recognition events through a conserved
carbohydrate-recognition domain (CRD). Most members of this family possess a
carbohydrate-binding activity that depends strictly on the binding of Ca2+ at
two sites, designated 1 and 2, in the CRD. The structural transitions associated
with Ca2+ binding in C-type lectins have been investigated by determining
high-resolution crystal structures of rat serum mannose-binding protein (MBP)
bound to one Ho3+ in place of Ca2+, and the apo form of rat liver MBP. The
removal of Ca2+ does not affect the core structure of the CRD, but dramatic
conformational changes occur in the loops. The most significant structural
change in the absence of Ca2+ is the isomerization of a cis-peptide bond
preceding a conserved proline residue in Ca2+ site 2. This bond adopts the cis
conformation in all Ca2+-bound structures, whereas both cis and trans
conformations are observed in the absence of Ca2+. The pattern of structural
changes in the three loops that interact with Ca2+ is dictated in large part by
the conformation of the prolyl peptide bond. The highly conserved nature of Ca2+
site 2 suggests that the transitions observed in MBPs are general features of
Ca2+ binding in C-type lectins.
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