IMR Press / FBL / Volume 14 / Issue 8 / DOI: 10.2741/3444

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Article
Insight into the actin-myosin motor from x-ray diffraction on muscle
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1 Institute of Immunology and Physiology, Russian Academy of Sciences, 91 Pervomayskaya ul. Yekaterinburg, 620041 Russia
2 Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, SW7 2AZ UK
3 Institute of Mechanics, Moscow University, 1 Mitchurinsky prosp. Moscow, 119992 Russia

Academic Editors: Marco Capitanio, Francesco Vanzi

Front. Biosci. (Landmark Ed) 2009, 14(8), 3188–3213; https://doi.org/10.2741/3444
Published: 1 January 2009
(This article belongs to the Special Issue Molecular motors)
Abstract

The origin of reflections in the x-ray diffraction pattern from striated muscle and their use for understanding the structural organization of the contractile machinery are presented and discussed. Results of x-ray diffraction experiments obtained by a number of research groups using a variety of protocols revealed structural changes in contracting muscles which are interpreted in terms of molecular movements that underlie force generation. Some of these data are in line with the widely accepted 'lever arm' hypothesis which links force generation to a tilt of the light chain domain of the myosin head with respect to its motor domain. However, changes in the layer line intensities observed in response to various perturbations cannot be explained by tilting of the lever arm. Such changes, first revealed in response to temperature jumps, are interpreted as a transition of non-stereo-specifically attached myosin heads to a stereo-specifically bound state. The new 'roll and lock' model considers force-generation as a two-stage process: initial stereo-specific locking of myosin heads on actin is followed by the lever arm tilt.

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