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PDBsum entry 2ox8
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Sugar binding protein
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PDB id
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2ox8
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References listed in PDB file
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Key reference
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Title
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Scavenger receptor c-Type lectin binds to the leukocyte cell surface glycan lewis X by a novel mechanism.
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Authors
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H.Feinberg,
M.E.Taylor,
W.I.Weis.
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Ref.
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J Biol Chem, 2007,
282,
17250-17258.
[DOI no: ]
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PubMed id
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Abstract
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The scavenger receptor C-type lectin (SRCL) is unique in the family of class A
scavenger receptors, because in addition to binding sites for oxidized
lipoproteins it also contains a C-type carbohydrate-recognition domain (CRD)
that interacts with specific glycans. Both human and mouse SRCL are highly
specific for the Lewisx trisaccharide, which is commonly found on the surfaces
of leukocytes and some tumor cells. Structural analysis of the CRD of mouse SRCL
in complex with Lewisx and mutagenesis show the basis for this specificity. The
interaction between mouse SRCL and Lewisx is analogous to the way that selectins
and DC-SIGN bind to related fucosylated glycans, but the mechanism of the
interaction is novel, because it is based on a primary galactose-binding site
similar to the binding site in the asialoglycoprotein receptor. Crystals of the
human receptor lacking bound calcium ions reveal an alternative conformation in
which a glycan ligand would be released during receptor-mediated endocytosis.
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Figure 2.
FIGURE 2. Structure of the CRD from SRCL. The CRD is shown
as a color ramp starting with blue at the N terminus and ending
in red at the C terminus. Disulfide bonds are shown in yellow.
A, human SRCL. Zn^2+ are shown as orange spheres. B, mouse SRCL
bound to Lewis^x. The oligosaccharide is shown in a stick
representation. Ca^2+ are shown as large green spheres.
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Figure 5.
FIGURE 5. Comparison of galactose-binding sites in C-type
CRDs. Carbon, nitrogen, oxygen, and calcium are represented as
white, blue, red, and green spheres, respectively. Hydrogen
bonds are shown as dashed gray lines, Ca^2+ coordination bonds
are dashed black lines and hydrophobic interactions are in
dashed blue lines. A, mouse SRCL. For simplicity only the
galactose residue of Lewis^x is shown. B, Gal/GalNAc-binding
mutant of mannose-binding protein complexed with GalNAc (1FIH,
copy A) (16). C, rattlesnake venom lectin complexed with lactose
(1JZN) (17). D, tunicate lectin complexed with galactose (1TLG)
(18).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2007,
282,
17250-17258)
copyright 2007.
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