scholarly journals Single turnovers of fluorescent ATP bound to bipolar myosin filament during actin filaments sliding

BIOPHYSICS ◽  
2013 ◽  
Vol 9 (0) ◽  
pp. 13-20
Author(s):  
Takahiro Maruta ◽  
Takahiro Kobatake ◽  
Hiroyuki Okubo ◽  
Shigeru Chaen
Keyword(s):  
Actin Filaments ◽  
Myosin Filament

Structure of Myosin Subfragment-1 from Electron Microscopy and Crystallography

1988 ◽  
Vol 46 ◽  
pp. 156-157
Author(s):  
Donald A. Winkelmann
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Actin Filaments ◽  
Light Chains ◽  
Myosin Filament ◽  
Primary Role ◽  
Heavy Chains ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
Globular Head

The primary role of the interaction of actin and myosin is the generation of force and motion as a direct consequence of the cyclic interaction of myosin crossbridges with actin filaments. Myosin is composed of six polypeptides: two heavy chains of molecular weight 220,000 daltons and two pairs of light chains of molecular weight 17,000-23,000. The C-terminal portions of the myosin heavy chains associate to form an α-helical coiled-coil rod which is responsible for myosin filament formation. The N-terminal portion of each heavy chain associates with two different light chains to form a globular head that binds actin and hydrolyses ATP. Myosin can be fragmented by limited proteolysis into several structural and functional domains. It has recently been demonstrated using an in vitro movement assay that the globular head domain, subfragment-1, is sufficient to cause sliding movement of actin filaments.The discovery of conditions for crystallization of the myosin subfragment-1 (S1) has led to a systematic analysis of S1 structure by x-ray crystallography and electron microscopy. Image analysis of electron micrographs of thin sections of small S1 crystals has been used to determine the structure of S1 in the crystal lattice.

scholarly journals Supercontracted state of vertebrate smooth muscle cell fragments reveals myofilament lengths.

1990 ◽  
Vol 111 (6) ◽  
pp. 2451-2461 ◽  
Author(s):  
J V Small ◽  
M Herzog ◽  
M Barth ◽  
A Draeger
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Cytoskeletal Proteins ◽  
Terminal Phase ◽  
Myosin Filament ◽  
Protein Loss ◽  
Whole Cells ◽  
Myosin Filaments ◽  
Central Bundle ◽  
Cell Fragments

Isolated cell preparations from chicken gizzard smooth muscle typically contain a mixture of cell fragments and whole cells. Both species are spontaneously permeable and may be preloaded with externally applied phalloidin and antibodies and then induced to contract with Mg ATP. Labeling with antibodies revealed that the cell fragments specifically lacked certain cytoskeletal proteins (vinculin, filamin) and were depleted to various degrees in others (desmin, alpha-actinin). The cell fragments showed a unique mode of supercontraction that involved the protrusion of actin filaments through the cell surface during the terminal phase of shortening. In the presence of dextran, to minimize protein loss, the supercontracted products were star-like in form, comprising long actin bundles radiating in all directions from a central core containing myosin, desmin, and alpha-actinin. It is concluded that supercontraction is facilitated by an effective uncoupling of the contractile apparatus from the cytoskeleton, due to partial degradation of the latter, which allows unhindered sliding of actin over myosin. Homogenization of the cell fragments before or after supercontraction produced linear bipolar dimer structures composed of two oppositely polarized bundles of actin flanking a central bundle of myosin filaments. Actin filaments were shown to extend the whole length of the bundles and their length averaged integral to 4.5 microns. Myosin filaments in the supercontracted dimers averaged 1.6 microns in length. The results, showing for the first time the high actin to myosin filament length ratio in smooth muscle are readily consistent with the slow speed of shortening of this tissue. Other implications of the results are also discussed.

Ultrastructure of the Striated Muscle of the Scallop (Placopecten magellanicus)

1968 ◽  
Vol 25 (7) ◽  
pp. 1339-1345 ◽  
Author(s):  
C. M. Morrison ◽  
P. H. Odense
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Actin Filaments ◽  
Striated Muscle ◽  
Adductor Muscle ◽  
Myosin Filament ◽  
Placopecten Magellanicus

The striated adductor muscle of the scallop Placopecten magellanicus is described. The fusiform uninucleate cells contain one fibril which is divided into A and I zones, and has Z and H bands. The A zone is 1.9 μ long, and in this zone apart from the H band about eight actin filaments surround each myosin filament. A sarcoplasmic reticulum envelops the fibril. Tubules of this reticulum are mainly oriented longitudinally and swellings from dyads with the sarcolemma.

scholarly journals X-ray Diffraction Studies on the Structural Origin of Dynamic Tension Recovery Following Ramp-Shaped Releases in High-Ca Rigor Muscle Fibers

2020 ◽  
Vol 21 (4) ◽  
pp. 1244
Author(s):  
Haruo Sugi ◽  
Maki Yamaguchi ◽  
Tetsuo Ohno ◽  
Hiroshi Okuyama ◽  
Naoto Yagi
Keyword(s):  
Muscle Contraction ◽  
Actin Filaments ◽  
Myosin Head ◽  
Muscle Fibers ◽  
Skinned Fibers ◽  
Myosin Filament ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tension Recovery ◽  
Pass Through

It is generally believed that during muscle contraction, myosin heads (M) extending from myosin filament attaches to actin filaments (A) to perform power stroke, associated with the reaction, A-M-ADP-Pi → A-M + ADP + Pi, so that myosin heads pass through the state of A-M, i.e., rigor A-M complex. We have, however, recently found that: (1) an antibody to myosin head, completely covering actin-binding sites in myosin head, has no effect on Ca2+-activated tension in skinned muscle fibers; (2) skinned fibers exhibit distinct tension recovery following ramp-shaped releases (amplitude, 0.5% of Lo; complete in 5 ms); and (3) EDTA, chelating Mg ions, eliminate the tension recovery in low-Ca rigor fibers but not in high-Ca rigor fibers. These results suggest that A-M-ADP myosin heads in high-Ca rigor fibers have dynamic properties to produce the tension recovery following ramp-shaped releases, and that myosin heads do not pass through rigor A-M complex configuration during muscle contraction. To obtain information about the structural changes in A-M-ADP myosin heads during the tension recovery, we performed X-ray diffraction studies on high-Ca rigor skinned fibers subjected to ramp-shaped releases. X-ray diffraction patterns of the fibers were recorded before and after application of ramp-shaped releases. The results obtained indicate that during the initial drop in rigor tension coincident with the applied release, rigor myosin heads take up applied displacement by tilting from oblique to perpendicular configuration to myofilaments, and after the release myosin heads appear to rotate around the helical structure of actin filaments to produce the tension recovery.

scholarly journals Unidirectional sliding of myosin filaments along the bundle of F-actin filaments spontaneously formed during superprecipitation.

1985 ◽  
Vol 101 (6) ◽  
pp. 2335-2344 ◽  
Author(s):  
S Higashi-Fujime
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Room Temperature ◽  
The Other ◽  
Reverse Direction ◽  
Myosin Filament ◽  
Bipolar Structure ◽  
Myosin Filaments ◽  
Direction Of Movement ◽  
Cold Spring

I reported previously (Higashi-Fujime, S., 1982, Cold Spring Harbor Symp. Quant. Biol., 46:69-75) that active movements of fibrils composed of F-actin and myosin filaments occurred after superprecipitation in the presence of ATP at low ionic strengths. When the concentration of MgCl2 in the medium used in the above experiment was raised to 20-26 mM, bundles of F-actin filaments, in addition to large precipitates, were formed spontaneously both during and after superprecipitation. Along these bundles, many myosin filaments were observed to slide unidirectionally and successively through the bundle, from one end to the other. The sliding of myosin filaments continued for approximately 1 h at room temperature at a mean rate of 6.0 micron/s, as long as ATP remained in the medium. By electron microscopy, it was found that most F-actin filaments decorated with heavy meromyosin pointed to the same direction in the bundle. Myosin filaments moved actively not only along the F-actin bundle but also in the medium. Such movement probably occurred along F-actin filaments that did not form the bundle but were dispersed in the medium, although dispersed F-actin filaments were not visible under the microscope. In this case, myosin filament could have moved in a reverse direction, changing from one F-actin filament to the other. These results suggested that the direction of movement of myosin filament, which has a bipolar structure and the potentiality to move in both directions, was determined by the polarity of F-actin filament in action.

scholarly journals The Kinetics Underlying the Velocity of Smooth Muscle Myosin Filament Sliding on Actin Filaments in vitro

2015 ◽  
Vol 108 (2) ◽  
pp. 9a
Author(s):  
Brian D. Haldeman ◽  
Richard K. Brizendine ◽  
Diego Alcala ◽  
Kevin C. Facemyer ◽  
Josh E. Baker ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Smooth Muscle Myosin ◽  
Myosin Filament ◽  
Muscle Myosin

scholarly journals Myosin filament polymerization and depolymerization in a model of partial length adaptation in airway smooth muscle

2011 ◽  
Vol 111 (3) ◽  
pp. 735-742 ◽  
Author(s):  
Gijs Ijpma ◽  
Ahmed M. Al-Jumaily ◽  
Simeon P. Cairns ◽  
Gary C. Sieck
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Actin Filaments ◽  
Isometric Force ◽  
Myosin Filament ◽  
Shortening Velocity ◽  
Partial Length ◽  
Myosin Filaments ◽  
Generating Capacity ◽  
Length Changes

Length adaptation in airway smooth muscle (ASM) is attributed to reorganization of the cytoskeleton, and in particular the contractile elements. However, a constantly changing lung volume with tidal breathing (hence changing ASM length) is likely to restrict full adaptation of ASM for force generation. There is likely to be continuous length adaptation of ASM between states of incomplete or partial length adaption. We propose a new model that assimilates findings on myosin filament polymerization/depolymerization, partial length adaptation, isometric force, and shortening velocity to describe this continuous length adaptation process. In this model, the ASM adapts to an optimal force-generating capacity in a repeating cycle of events. Initially the myosin filament, shortened by prior length changes, associates with two longer actin filaments. The actin filaments are located adjacent to the myosin filaments, such that all myosin heads overlap with actin to permit maximal cross-bridge cycling. Since in this model the actin filaments are usually longer than myosin filaments, the excess length of the actin filament is located randomly with respect to the myosin filament. Once activated, the myosin filament elongates by polymerization along the actin filaments, with the growth limited by the overlap of the actin filaments. During relaxation, the myosin filaments dissociate from the actin filaments, and then the cycle repeats. This process causes a gradual adaptation of force and instantaneous adaptation of shortening velocity. Good agreement is found between model simulations and the experimental data depicting the relationship between force development, myosin filament density, or shortening velocity and length.

scholarly journals The N terminus of myosin-binding protein C extends toward actin filaments in intact cardiac muscle

2021 ◽  
Vol 153 (3) ◽  
Author(s):  
Sheema Rahmanseresht ◽  
Kyoung H. Lee ◽  
Thomas S. O’Leary ◽  
James W. McNamara ◽  
Sakthivel Sadayappan ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Protein C ◽  
Myosin Head ◽  
Binding Protein ◽  
Myosin Filament ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
N Terminus ◽  
Myosin Binding ◽  
Terminal Domains

Myosin and actin filaments are highly organized within muscle sarcomeres. Myosin-binding protein C (MyBP-C) is a flexible, rod-like protein located within the C-zone of the sarcomere. The C-terminal domain of MyBP-C is tethered to the myosin filament backbone, and the N-terminal domains are postulated to interact with actin and/or the myosin head to modulate filament sliding. To define where the N-terminal domains of MyBP-C are localized in the sarcomere of active and relaxed mouse myocardium, the relative positions of the N terminus of MyBP-C and actin were imaged in fixed muscle samples using super-resolution fluorescence microscopy. The resolution of the imaging was enhanced by particle averaging. The images demonstrate that the position of the N terminus of MyBP-C is biased toward the actin filaments in both active and relaxed muscle preparations. Comparison of the experimental images with images generated in silico, accounting for known binding partner interactions, suggests that the N-terminal domains of MyBP-C may bind to actin and possibly the myosin head but only when the myosin head is in the proximity of an actin filament. These physiologically relevant images help define the molecular mechanism by which the N-terminal domains of MyBP-C may search for, and capture, molecular binding partners to tune cardiac contractility.

scholarly journals Fluctuation analysis of sliding movement of actin filaments along molluscan myosin filament.

2000 ◽  
Vol 40 (supplement) ◽  
pp. S200
Author(s):  
S. Takada ◽  
A. Yamada ◽  
Y. Imafuku ◽  
K. Tawada
Keyword(s):  
Actin Filaments ◽  
Myosin Filament ◽  
Fluctuation Analysis
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