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PDBsum entry 2jtd
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Cell adhesion
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PDB id
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2jtd
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References listed in PDB file
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Key reference
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Title
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Structural insight into the interaction between platelet integrin alphaiibbeta3 and cytoskeletal protein skelemin.
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Authors
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L.Deshmukh,
S.Tyukhtenko,
J.Liu,
J.E.Fox,
J.Qin,
O.Vinogradova.
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Ref.
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J Biol Chem, 2007,
282,
32349-32356.
[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 have
been manually determined.
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Abstract
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Skelemin is a large cytoskeletal protein critical for cell morphology. Previous
studies have suggested that its two-tandem immunoglobulin C2-like repeats
(SkIgC4 and SkIgC5) are involved in binding to integrin beta3 cytoplasmic tail
(CT), providing a mechanism for skelemin to regulate integrin-mediated signaling
and cell spreading. Using NMR spectroscopy, we have studied the molecular
details of the skelemin IgC45 interaction with the cytoplasmic face of integrin
alphaIIbbeta3. Here, we show that skelemin IgC45 domains form a complex not only
with integrin beta3 CT but also, surprisingly, with the integrin alphaIIb CT.
Chemical shift mapping experiments demonstrate that both membrane-proximal
regions of alphaIIb and beta3 CTs are involved in binding to skelemin. NMR
structural determinations, combined with homology modeling, revealed that SkIgC4
and SkIgC5 both exhibited a conserved Ig-fold and both repeats were required for
effective binding to and attenuation of alphaIIbbeta3 cytoplasmic complex. These
data provide the first molecular insight into how skelemin may interact with
integrins and regulate integrin-mediated signaling and cell spreading.
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Figure 1.
Composition of skelemin.A, skelemin contains one unique
region, one serine/proline-rich region, seven Ig-C2-like and
five FN-like domains. SkIgC4 and SkIgC5 domains, squared in this
figure, have been implicated in integrin binding. B, primary
sequences and alignment of skelemin Ig-C2 domains 4 and 5.
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Figure 2.
Summary of the spectral perturbations for integrin
β[3]/skelemin and α[IIb]/skelemin interactions. All
experiments were performed in 0.25× PBS (pH 6.2) buffer at
25 °C. A, expanded region of HSQC spectra of ^15N-labeled
β[3] tail in the absence (black) and presence of the unlabeled
skelemin IgC45 at different ratios: 1:1, green; 1:3, red; 1:5,
blue. Residues labeled indicate the most significant changes. B,
chemical shift changes of the β[3] tail upon SkIgC45 binding.
Bars are colored according to the different ratios as presented
in A. First nine residues (Lys^716-Arg^724) in 1:5 (blue) series
are undetectable because of extreme line-broadening and are
shown as bars with maximum values. C, chemical shift changes of
the β[3] tail upon binding to different skelemin constructs at
the ratio of 1:3. Bars are colored according to the interaction
with a particular domain of skelemin: green bars, interaction
with SkIgC4; blue bars, interaction with SkIgC5; red bars,
interaction with SkIgC45. The last bar in each series represents
chemical shifts of the Trp^739 side-chain HN; His^722 is
undetectable (probably because of the exchange with water) and
is not shown in green and blue series. Δδ(HN,N) in ppm refers
to the combined HN and N chemical shift changes, according to
the equation: Δδ(HN,N) = ((Δδ[HN]^2 + 0.2
(Δδ[N])^2)[½], where Δδ = δ[bound] - δ[free]. D,
HSQC spectra of ^15N/^2H-labeled skelemin IgC45 in the absence
(black) and presence (red) of the unlabeled β[3] tail. E, HSQC
spectra of ^15N-labeled α[IIb] in the absence (black) or
presence (red) of unlabeled SkIgC45 at the ratio of 1:5.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2007,
282,
32349-32356)
copyright 2007.
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