Interactions between actin and myosin filaments in skeletal muscle visualized in frozen-hydrated thin sections

Détails

ID Serval
serval:BIB_EFF5E7AAEB6E
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Interactions between actin and myosin filaments in skeletal muscle visualized in frozen-hydrated thin sections
Périodique
Biophysical Journal
Auteur(s)
Trus  B. L., Steven  A. C., McDowall  A. W., Unser  M., Dubochet  J., Podolsky  R. J.
ISSN
0006-3495 (Print)
Statut éditorial
Publié
Date de publication
04/1989
Volume
55
Numéro
4
Pages
713-24
Notes
Comparative Study
In Vitro
Journal Article --- Old month value: Apr
Résumé
For the purpose of determining net interactions between actin and myosin filaments in muscle cells, perhaps the single most informative view of the myofilament lattice is its averaged axial projection. We have studied frozen-hydrated transverse thin sections with the goal of obtaining axial projections that are not subject to the limitations of conventional thin sectioning (suspect preservation of native structure) or of equatorial x-ray diffraction analysis (lack of experimental phases). In principle, good preservation of native structure may be achieved with fast freezing, followed by low-dose electron imaging of unstained vitrified cryosections. In practice, however, cryosections undergo large-scale distortions, including irreversible compression; furthermore, phase contrast imaging results in a nonlinear relationship between the projected density of the specimen and the optical density of the micrograph. To overcome these limitations, we have devised methods of image restoration and generalized correlation averaging, and applied them to cryosections of rabbit psoas fibers in both the relaxed and rigor states. Thus visualized, myosin filaments appear thicker than actin filaments by a much smaller margin than in conventional thin sections, and particularly so for rigor muscle. This may result from a significant fraction of the myosin S1-cross-bridges averaging out in projection and thus contributing only to the baseline of projected density. Entering rigor incurs a loss of density from an annulus around the myosin filament, with a compensating accumulation of density around the actin filament. This redistribution of mass represents attachment of the fraction of cross-bridges that are visible above background. Myosin filaments in the "nonoverlap" zone appear to broaden on entering rigor, suggesting that on deprivation of ATP, cross-bridges in situ move outwards even without actin in their immediate proximity.
Mots-clé
Actins/*metabolism/ultrastructure Animals Freezing Microscopy, Electron/methods Muscles/*physiology/ultrastructure Myosins/*metabolism/ultrastructure Rabbits X-Ray Diffraction/methods
Pubmed
Web of science
Création de la notice
24/01/2008 11:25
Dernière modification de la notice
03/03/2018 22:35
Données d'usage