A single myosin head moves along an actin filament with regular steps of 5.3 nanometres

Nature ◽  
10.1038/16403 ◽  
1999 ◽  
Vol 397 (6715) ◽  
pp. 129-134 ◽  
Author(s):  
Kazuo Kitamura ◽  
Makio Tokunaga ◽  
Atsuko Hikikoshi Iwane ◽  
Toshio Yanagida
Keyword(s):  
Actin Filament ◽  
Myosin Head

scholarly journals A Single Myosin Head Moves along an Actin Filament with Regular Steps during One Biochemical Cycle of ATP Hydrolysis

2000 ◽  
Vol 40 (2) ◽  
pp. 89-93 ◽  
Author(s):  
Kazuo KITAMURA ◽  
Atsuko H. IWANE ◽  
Makio TOKUNAGA
Keyword(s):  
Actin Filament ◽  
Atp Hydrolysis ◽  
Myosin Head

scholarly journals Mechanical model of muscle contraction 2. Kinematic and dynamic aspects of a myosin II head during the working stroke

2019 ◽  
Author(s):  
S. Louvet
Keyword(s):  
Actin Filament ◽  
Myosin Head ◽  
Myosin Ii ◽  
Tangential Force ◽  
Longitudinal Axis ◽  
Myosin Filament ◽  
Analytical Relationship ◽  
Shortening Velocity ◽  
Fixed Plane ◽  
Algorithmic Optimization

AbstractThe condition of a myosin II head during which force and movement are generated is commonly referred to as Working Stroke (WS). During the WS, the myosin head is mechanically modelled by 3 two by two articulated segments, the motor domain (S1a) strongly fixed to an actin molecule, the lever (S1b) on which a motor moment is exerted, and the rod (S2) pulling the myosin filament (Mfil). When the half-sarcomere (hs) is shortened or lengthened by a few nanometers, it is assumed that the lever of a myosin head in WS state moves in a fixed plane including the longitudinal axis of the actin filament (Afil). As a result, the 5 rigid segments, i.e. Afil, S1a, S1b, S2 and Mfil, follow deterministic and configurable trajectories. The orientation of S1b in the fixed plane is characterized by the angle θ. After deriving the geometric equations singularizing the WS state, we obtain an analytical relationship between the hs shortening velocity (u) and the angular velocity of the lever . The principles of classical mechanics applied to the 3 solids, S1a, S1b and S2, lead to a relationship between the motor moment exerted on the lever (MB) and the tangential force dragging the actin filament (TA). We distinguish θup and θdown, the two boundaries framing the angle θ during the WS, relating to up and down conformations. With the usual data assigned to the cross-bridge elements, a linearization procedure of the relationships between u and , on the one hand, and between MB and TA, on the other hand, is performed. This algorithmic optimization leads to theoretical values of θup and θdown equal to +28° (−28°) and −42° (+42°) respectively with a variability of ±5° in a hs on the right (left), data in accordance with the commonly accepted experimental values for vertebrate muscle fibers.

Actomyosin interaction in striated muscle

1997 ◽  
Vol 77 (3) ◽  
pp. 671-697 ◽  
Author(s):  
R. Cooke
Keyword(s):  
Actin Filament ◽  
Striated Muscle ◽  
Myosin Head ◽  
Three Dimensional ◽  
Step Length ◽  
Myosin Molecule ◽  
Actin Monomer ◽  
Active Fiber ◽  
Actomyosin Interaction ◽  
Dimensional Crystal

The mechanics of the actomyosin interaction have been extensively studied using the organized filament array of striated muscle. However, the extrapolation of these data to the events occurring at the level of a single actomyosin interaction has not been simple. Problems arise in part because an active fiber has an ensemble of myosin heads that are spread out through the various steps of the active cycle, and it is likely that only a small fraction of the heads are generating tension at any given time. More recently, two new approaches have greatly extended our knowledge of the actomyosin interaction. First, the three-dimensional crystal structures of both the actin monomer and the myosin head have been determined, and these structures have been fit to lower resolution images to give atomic models of the actin filament and of the actin filament decorated by myosin heads. Second, the technology to measure picoNewton forces and nanometer distances has provided direct determinations of the force and step length generated by a single myosin molecule interacting with a single actin filament. This review synthesizes the existing mechanical data obtained from the more-organized array of the muscle filament with the results obtained by these two technologies.

Proposed Modification of the Huxley—Simmons Model for Myosin Head Motion along an Actin Filament

1996 ◽  
Vol 182 (2) ◽  
pp. 147-159 ◽  
Author(s):  
Toshio Mitsui ◽  
Hisahiro Chiba
Keyword(s):  
Actin Filament ◽  
Myosin Head ◽  
Head Motion ◽  
Proposed Modification

Toward an alignment of the actin molecule within the actin filament

1983 ◽  
Vol 41 ◽  
pp. 450-451
Author(s):  
P.R. Smith ◽  
W.E. Fowler ◽  
U. Aebi
Keyword(s):  
Actin Filament ◽  
Diffraction Data ◽  
Quantitative Estimate ◽  
Molecular Model ◽  
Quantitative Comparison ◽  
Regulatory Proteins ◽  
Essential Information ◽  
X Ray ◽  
Maximum Resolution ◽  
Lack Of Information

An understanding of the specific interactions of actin with regulatory proteins has been limited by the lack of information about the structure of the actin filament. Molecular actin has been studied in actin-DNase I complexes by single crystal X-ray analysis, to a resolution of about 0.6nm, and in the electron microscope where two dimensional actin sheets have been reconstructed to a maximum resolution of 1.5nm. While these studies have shown something of the structure of individual actin molecules, essential information about the orientation of actin in the filament is still unavailable.The work of Egelman & DeRosier has, however, suggested a method which could be used to provide an initial quantitative estimate of the orientation of actin within the filament. This method involves the quantitative comparison of computed diffraction data from single actin filaments with diffraction data derived from synthetic filaments constructed using the molecular model of actin as a building block. Their preliminary work was conducted using a model consisting of two juxtaposed spheres of equal size.

Orientation of actin filaments during motion in motility assay

1995 ◽  
Vol 53 ◽  
pp. 52-53
Author(s):  
J. Borejdo ◽  
S. Burlacu
Keyword(s):  
Actin Filaments ◽  
Thin Filament ◽  
Striated Muscle ◽  
Myosin Head ◽  
Classical Method ◽  
Polarization Of Fluorescence ◽  
Single Protein ◽  
Intracellular Organelles ◽  
Change Orientation ◽  
Active Entity

Polarization of fluorescence is a classical method to assess orientation or mobility of macromolecules. It has been a common practice to measure polarization of fluorescence through a microscope to characterize orientation or mobility of intracellular organelles, for example anisotropic bands in striated muscle. Recently, we have extended this technique to characterize single protein molecules. The scientific question concerned the current problem in muscle motility: whether myosin heads or actin filaments change orientation during contraction. The classical view is that the force-generating step in muscle is caused by change in orientation of myosin head (subfragment-1 or SI) relative to the axis of thin filament. The molecular impeller which causes this change resides at the interface between actin and SI, but it is not clear whether only the myosin head or both SI and actin change orientation during contraction. Most studies assume that observed orientational change in myosin head is a reflection of the fact that myosin is an active entity and actin serves merely as a passive "rail" on which myosin moves.

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