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PDBsum entry 1qvi
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Contractile protein
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PDB id
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1qvi
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Contents |
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806 a.a.
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141 a.a.
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155 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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Crystal structure of scallop myosin s1 in the pre-Power stroke state to 2.6 a resolution: flexibility and function in the head.
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Authors
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S.Gourinath,
D.M.Himmel,
J.H.Brown,
L.Reshetnikova,
A.G.Szent-Györgyi,
C.Cohen.
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Ref.
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Structure, 2003,
11,
1621-1627.
[DOI no: ]
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PubMed id
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Abstract
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We have extended the X-ray structure determination of the complete scallop
myosin head in the pre-power stroke state to 2.6 A resolution, allowing an
atomic comparison of the three major (weak actin binding) states of various
myosins. We can now account for conformational differences observed in crystal
structures in the so-called "pliant region" at the motor domain-lever
arm junction between scallop and vertebrate smooth muscle myosins. A hinge,
which may contribute to the compliance of the myosin crossbridge, has also been
identified for the first time within the regulatory light-chain domain of the
lever arm. Analysis of temperature factors of key joints of the motor domain,
especially the SH1 helix, provides crystallographic evidence for the existence
of the "internally uncoupled" state in diverse isoforms. The agreement
between structural and solution studies reinforces the view that the unwinding
of the SH1 helix is a part of the cross-bridge cycle in many myosins.
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Figure 1.
Figure 1. Stabilizing Interactions in the So-Called "Pliant
Region"--the MD/Lever Arm Junction--in Scallop S1(A) Displayed
here is a schematic comparison between the pliant regions of the
chicken smooth muscle MDE-MgADP·AlF[4] structure (Dominguez et
al., 1998) (gray, only the lever arm is shown) and scallop
S1-MgADP·VO[4] (the lever arm and motor domain are shown). These
structures are superimposed by fitting the residues (765-773)
immediately N-terminal to the "pliant region." The pliant region
is straight in all scallop S1 structures but is bent in the
chicken smooth muscle crystal structure (Dominguez et al., 1998)
(also see text). The lever arm heavy chain is shown as a ribbon
diagram in purple, and the motor domain is shown schematically
with its subdomains (the 50 kDa upper and lower subdomains in
red and pink, the N-terminal subdomain in blue, the converter in
green, and the pliant helix in yellow).(B) As in (A) but from a
perpendicular view and also showing the scallop light chains
schematically (ELC in magenta, and RLC in light blue).(C)
Magnified view of the pliant region of scallop S1 (in the same
orientation as in [B] and including the ELC in magenta) shows
the side chain interactions that appear to restrain the scallop
pliant region from bending (salt bridges in red dashed lines,
van der Waals contacts in blue dashed lines). These interactions
are absent from the smooth muscle MDE crystal structure as a
result of amino acid sequence differences from scallop myosin.
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2003,
11,
1621-1627)
copyright 2003.
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