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PDBsum entry 2fjg
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Hormone/growth factor/immune system
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PDB id
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2fjg
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Contents |
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95 a.a.
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211 a.a.
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218 a.a.
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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-Function studies of two synthetic anti-Vascular endothelial growth factor fabs and comparison with the avastin fab.
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Authors
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G.Fuh,
P.Wu,
W.C.Liang,
M.Ultsch,
C.V.Lee,
B.Moffat,
C.Wiesmann.
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Ref.
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J Biol Chem, 2006,
281,
6625-6631.
[DOI no: ]
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PubMed id
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Abstract
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In the quest to discover new research tools and to develop better agents in the
fight against cancer, two antibodies, G6 and B20-4, were isolated from synthetic
antibody phage libraries. Unlike the AVASTINtrade mark antibody, a recently
approved agent for the treatment of patients with colorectal cancer, B20-4 and
G6 bind and block both human and murine vascular endothelial growth factor
(VEGF). Here we have analyzed and compared the binding epitopes on VEGF for
these three antibodies using alanine-scanning mutagenesis and structural
analyses. The epitopes recognized by both synthetic antibodies are conserved
between human and mouse VEGF, and they match closely to the receptor epitopes
both structurally and functionally. In contrast, the Avastin epitope overlaps
minimally with the receptor binding surface and centers around a residue that is
not conserved in mouse. Our structural and functional analyses elucidate the
cross-species reactivity of all three antibodies and emphasize the potential
advantages of antibody generation using phage display as the resulting
antibodies do not depend on sequence differences across species and
preferentially target natural protein-protein interaction surfaces.
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Figure 4.
FIGURE 4. G6 bound to VEGF (shown in red) and G6 in its
unbound form (green) superimposed on a number of Fab fragments
in two different views. Shown are B20-4 (yellow), the
Avastin-Fab (blue), and 4D5 (Protein Data Bank code 1FVC, in
white), which adopt canonical conformations, as well as a
selection of Fabs that have non-canonical conformations in
CDR-H2 (Protein Data Bank codes 1IND, 1BBJ, 1FIG, 6FAB, all
shown in white). Note the significant conformational shift of
the G6 CDR-H2 upon VEGF binding.
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Figure 5.
FIGURE 5. Common hot spot of VEGF for binding of VEGFR1,
G6, and B20-4. Depicted is the surface of VEGF. All residues
that form contacts with VEGFR1, G6, and B20-4 are colored
yellow, and all residues that when exchanged to alanine cause a
loss in binding affinity of >4-fold in all three complexes are
colored red. All residues that differ in the sequence between
mouse and human VEGF are green. Only 5 of the 10 residues that
differ in the receptor binding domain of human and murine VEGF
are labeled; the remaining 5 residues are disordered in the
crystal structure of the VEGF or more distant from the binding
interface of the molecules investigated here.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2006,
281,
6625-6631)
copyright 2006.
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