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PDBsum entry 1v7m
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Immune system/cytokine
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PDB id
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1v7m
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Contents |
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212 a.a.
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217 a.a.
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145 a.a.
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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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Structure of the receptor-Binding domain of human thrombopoietin determined by complexation with a neutralizing antibody fragment.
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Authors
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M.D.Feese,
T.Tamada,
Y.Kato,
Y.Maeda,
M.Hirose,
Y.Matsukura,
H.Shigematsu,
T.Muto,
A.Matsumoto,
H.Watarai,
K.Ogami,
T.Tahara,
T.Kato,
H.Miyazaki,
R.Kuroki.
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Ref.
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Proc Natl Acad Sci U S A, 2004,
101,
1816-1821.
[DOI no: ]
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PubMed id
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Abstract
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The cytokine thrombopoietin (TPO), the ligand for the hematopoietic receptor
c-Mpl, acts as a primary regulator of megakaryocytopoiesis and platelet
production. We have determined the crystal structure of the receptor-binding
domain of human TPO (hTPO(163)) to a 2.5-A resolution by complexation with a
neutralizing Fab fragment. The backbone structure of hTPO(163) has an
antiparallel four-helix bundle fold. The neutralizing Fab mainly recognizes the
C-D crossover loop containing the species invariant residue Q111. Titration
calorimetric experiments show that hTPO(163) interacts with soluble c-Mpl
containing the extracellular cytokine receptor homology domains with 1:2
stoichiometry with the binding constants of 3.3 x 10(9) M(-1) and 1.1 x 10(6)
M(-1). The presence of the neutralizing Fab did not inhibit binding of hTPO(163)
to soluble c-Mpl fragments, but the lower-affinity binding disappeared. Together
with prior genetic data, these define the structure-function relationships in
TPO and the activation scheme of c-Mpl.
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Figure 3.
Fig. 3. hTPO[163]-TN1-Fab complex. The C  traces
for the heavy and light chains of the variable domains of the
TN1-Fab are shown in green and blue. Only residues that interact
with hTPO[163] are shown. hTPO[163] is shown in the
Corey-Pauling-Koltun molecular model (CPK) with residues that
interact with the TN1-Fab highlighted as individually colored
CPK atoms. Regions of hTPO[163] that do not interact with the
TN1-Fab are shown as solid orange CPK.
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Figure 5.
Fig. 5. Determinants of specificity of TPO for c-Mpl.
Residues that are invariant within the TPO family but not
conserved in the EPO family are proposed to confer specificity
to the TPO-c-Mpl interaction. These residues fall into two
distinct clusters corresponding to the proposed high-affinity
(blue) and low-affinity (green) receptor interaction sites.
Residues that are invariant in the TPO/EPO family are shown in
black.
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Secondary reference #1
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Title
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Crystallization of the functional domain of human thrombopoietin using an antigen-Binding fragment derived from neutralizing monoclonal antibody.
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Authors
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R.Kuroki,
M.Hirose,
Y.Kato,
M.D.Feese,
T.Tamada,
H.Shigematsu,
H.Watarai,
Y.Maeda,
T.Tahara,
T.Kato,
H.Miyazaki.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2002,
58,
856-858.
[DOI no: ]
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PubMed id
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Figure 1.
Figure 1 Crystals of TPO[163]-Fab complex. Approximate
dimensions of the crystal are 0.2 × 0.2 × 0.02 mm.
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The above figure is
reproduced from the cited reference
with permission from the IUCr
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