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PDBsum entry 1g1c
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Structural protein
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PDB id
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1g1c
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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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Structural evidence for a possible role of reversible disulphide bridge formation in the elasticity of the muscle protein titin.
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Authors
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O.Mayans,
J.Wuerges,
S.Canela,
M.Gautel,
M.Wilmanns.
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Ref.
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Structure, 2001,
9,
331-340.
[DOI no: ]
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PubMed id
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Abstract
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BACKGROUND: The giant muscle protein titin contributes to the filament system in
skeletal and cardiac muscle cells by connecting the Z disk and the central M
line of the sarcomere. One of the physiological functions of titin is to act as
a passive spring in the sarcomere, which is achieved by the elastic properties
of its central I band region. Titin contains about 300 domains of which more
than half are folded as immunoglobulin-like (Ig) domains. Ig domain segments of
the I band of titin have been extensively used as templates to investigate the
molecular basis of protein elasticity. RESULTS: The structure of the Ig domain
I1 from the I band of titin has been determined to 2.1 A resolution. It reveals
a novel, reversible disulphide bridge, which is neither required for correct
folding nor changes the chemical stability of I1, but it is predicted to
contribute mechanically to the elastic properties of titin in active sarcomeres.
From the 92 Ig domains in the longest isoform of titin, at least 40 domains have
a potential for disulphide bridge formation. CONCLUSIONS: We propose a model
where the formation of disulphide bridges under oxidative stress conditions
could regulate the elasticity of the I band in titin by increasing sarcomeric
resistance. In this model, the formation of the disulphide bridge could refrain
a possible directed motion of the two beta sheets or other mechanically stable
entities of the I1 Ig domain with respect to each other when exposed to
mechanical forces.
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Figure 1.
Figure 1. Overall Structure of the I1 Ig Domain(a) Ribbon
representation. b strands of the sheets ABDE and the A'CC'FG are
color coded in pink and cyan, respectively. The two loops B-C
and F-G, close to the N terminus, are colored in light green and
dark green, respectively. The two loops A'-B and E-F, close to
the C terminus, are colored in orange and brown,
respectively.(b) Same presentation as (a) but tilted. The
disulphide bridge connecting residues 37 (b strand C) and 62 (b
strand E) is shown in ball-and-stick representation. The 3
tryptophan residues (W39, W54, and W56) surrounding the
disulphide bridge are also included.(c) Stereoview of the
2F[o]-F[c] (a[calc]) electron density map of the disulphide
bridge region contoured at 1.5 s
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2001,
9,
331-340)
copyright 2001.
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