Evidence for pre- and post-power stroke of cross-bridges of contracting skeletal myofibrils.
Biophys J
; 100(4): 1024-33, 2011 Feb 16.
Article
de En
| MEDLINE
| ID: mdl-21320447
ABSTRACT
We examined the orientational fluctuations of a small number of myosin molecules (approximately three) in working skeletal muscle myofibrils. Myosin light chain 1 (LC1) was labeled with a fluorescent dye and exchanged with the native LC1 of skeletal muscle myofibrils cross-linked with 1-ethyl-3-[3(dimethylamino) propyl] carbodiimide to prevent shortening. We observed a small volume within the A-band (â¼10(-15) L) by confocal microscopy, and measured cyclic fluctuations in the orientation of the myosin neck (containing LC1) by recording the parallel and perpendicular components of fluorescent light emitted by the fluorescently labeled myosin LC1. Histograms of orientational fluctuations from fluorescent molecules in rigor were represented by a single Gaussian distribution. In contrast, histograms from contracting muscles were best fit by at least two Gaussians. These results provide direct evidence that cross-bridges in working skeletal muscle assume two distinct conformations, presumably corresponding to the pre- and post-power-stroke states.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Muscles squelettiques
/
Contraction musculaire
/
Myofibrilles
Limites:
Animals
Langue:
En
Journal:
Biophys J
Année:
2011
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique