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Three-dimensional structure of the M-region (bare zone) of vertebrate striated muscle myosin filaments by single-particle analysis.

Authors :
Al-Khayat HA
Kensler RW
Morris EP
Squire JM
Source :
Journal of molecular biology [J Mol Biol] 2010 Nov 12; Vol. 403 (5), pp. 763-76. Date of Electronic Publication: 2010 Sep 17.
Publication Year :
2010

Abstract

The rods of anti-parallel myosin molecules overlap at the centre of bipolar myosin filaments to produce an M-region (bare zone) that is free of myosin heads. Beyond the M-region edges, myosin molecules aggregate in a parallel fashion to yield the bridge regions of the myosin filaments. Adjacent myosin filaments in striated muscle A-bands are cross-linked by the M-band. Vertebrate striated muscle myosin filaments have a 3-fold rotational symmetry around their long axes. In addition, at the centre of the M-region, there are three 2-fold axes perpendicular to the filament long axis, giving the whole filament dihedral 32-point group symmetry. Here we describe the three-dimensional structure obtained by a single-particle analysis of the M-region of myosin filaments from goldfish skeletal muscle under relaxing conditions and as viewed in negative stain. This is the first single-particle reconstruction of isolated M-regions. The resulting three-dimensional reconstruction reveals details to about 55 Å resolution of the density distribution in the five main nonmyosin densities in the M-band (M6', M4', M1, M4 and M6) and in the myosin head crowns (P1, P2 and P3) at the M-region edges. The outermost crowns in the reconstruction were identified specifically by their close similarity to the corresponding crown levels in our previously published bridge region reconstructions. The packing of myosin molecules into the M-region structure is discussed, and some unidentified densities are highlighted.<br /> (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Details

Language :
English
ISSN :
1089-8638
Volume :
403
Issue :
5
Database :
MEDLINE
Journal :
Journal of molecular biology
Publication Type :
Academic Journal
Accession number :
20851129
Full Text :
https://doi.org/10.1016/j.jmb.2010.09.025