Corrections - Myosin Subfragment 1 Binding to Relaxed Actin Filaments and Steric Model of Relaxation

Biochemistry ◽  
1981 ◽  
Vol 20 (17) ◽  
pp. 5094-5094
Author(s):  
John Murray ◽  
Annemarie Weber ◽  
Mary Knox
Keyword(s):  
Actin Filaments ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1

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.

Myosin subfragment 1 binding to relaxed actin filaments and steric model of relaxation

Biochemistry ◽  
1981 ◽  
Vol 20 (3) ◽  
pp. 641-649 ◽  
Author(s):  
John M. Murray ◽  
Annemarie Weber ◽  
Mary K. Knox
Keyword(s):  
Actin Filaments ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1

scholarly journals Regulation of the acto·myosin subfragment 1 interaction by troponin/tropomyosin. Evidence for control of a specific isomerization between two acto·myosin subfragment 1 states

1991 ◽  
Vol 279 (3) ◽  
pp. 711-718 ◽  
Author(s):  
D F A McKillop ◽  
M A Geeves
Keyword(s):  
Skeletal Muscle ◽  
Active Site ◽  
Actin Filaments ◽  
Thin Filaments ◽  
Closed State ◽  
Myosin Subfragment ◽  
Actomyosin Interaction ◽  
Binding Isotherms ◽  
Myosin Subfragment 1 ◽  
Site Binding

The co-operative binding of myosin subfragment 1 (S1) to reconstituted skeletal-muscle thin filaments has been examined by monitoring the fluorescence of a pyrene probe on Cys-374 of actin. The degree of co-operativity differs when phosphate, sulphate or ADP are bound to the S1 active site. Binding isotherms have been analysed according to the Geeves & Halsall [(1987) Biophys. J. 52, 215-220] model, which proposed that troponin and tropomyosin effected regulation of the actomyosin interaction by controlling an isomerization of the actomyosin complex. The data support the proposal that seven actin monomers associated with a single tropomyosin molecule act as a co-operative unit that can be in one of two states. In the ‘closed’ state myosin can bind to actin, but the subsequent isomerization is prevented. The isomerization is only allowed after the seven-actin unit is in the ‘open’ form. Ca2+ controls the proportion of actin filaments in the ‘closed’ and ‘open’ forms in the absence of myosin heads. The ratio of ‘closed’ to ‘open’ forms is approx. 50:1 in the absence of Ca2+ and 5:1 in its presence.

scholarly journals The visualization of actin filament polarity in thin sections. Evidence for the uniform polarity of membrane-associated filaments.

1978 ◽  
Vol 79 (3) ◽  
pp. 846-852 ◽  
Author(s):  
D A Begg ◽  
R Rodewald ◽  
L I Rebhun
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Intestinal Epithelial ◽  
Improved Method ◽  
Thin Sections ◽  
Myosin Subfragment ◽  
Brush Borders ◽  
Nonmuscle Cells ◽  
Myosin Subfragment 1 ◽  
Uniform Polarity

We have developed an improved method for visualizing actin filament polarity in thin sections. Myosin subfragment-1 (S-1)-decorated actin filaments display a dramatically enhanced arrowhead configuration when fixed in a medium which contains 0.2 % tannic acid. With the exception of brush borders from intestinal epithelial cells, the arrowhead periodicity of decorated filaments in a variety of nonmuscle cells is similar to that in isolated myofibrils. The periodicity of decorated filaments in brush borders is significantly smaller. Actin filaments which attach to membranes display a clear, uniform polarity, with the S-1 arrowheads pointing away from the plasma membrane, while those which comprise the stress fibers of myoblasts and CHO cells have antiparallel polarities. These observations are consistent with a sliding filament mechanism of cell motility.

Myosin subfragment-1 is sufficient to move actin filaments in vitro

Nature ◽  
1987 ◽  
Vol 328 (6130) ◽  
pp. 536-539 ◽  
Author(s):  
Yoko Yano Toyoshima ◽  
Stephen J. Kron ◽  
Elizabeth M. McNally ◽  
Kenneth R. Niebling ◽  
Chikashi Toyoshima ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1

scholarly journals A membrane cytoskeleton from Dictyostelium discoideum. III. Plasma membrane fragments bind predominantly to the sides of actin filaments.

1984 ◽  
Vol 99 (1) ◽  
pp. 71-78 ◽  
Author(s):  
C M Goodloe-Holland ◽  
E J Luna
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Dictyostelium Discoideum ◽  
Electron Micrographs ◽  
Actin Filaments ◽  
Lateral Movement ◽  
Heavy Meromyosin ◽  
Membrane Cytoskeleton ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1

The binding between sonicated Dictyostelium discoideum plasma membrane fragments and F-actin on Sephacryl S-1000 beads was found to be competitively inhibited by myosin subfragment-1. This inhibition is MgATP-sensitive, exhibits a Ki of approximately 5 X 10(-8) M, and is reciprocal, since membranes inhibit the binding of 125I-heavy meromyosin to F-actin on beads. These experiments demonstrate that membrane binding and S-1 binding to F-actin on beads are mutually exclusive and, therefore, that the membrane fragments bind predominantly to the sides, rather than to the ends, of the actin filaments. This conclusion is supported by electron micrographs that show many lateral associations between membrane fragments and bead-associated actin filaments. Such lateral associations could play an important role in the organization and lateral movement of membrane proteins by the cytomusculature.

scholarly journals Identification of actin filaments in the rhabdomeral microvilli of Drosophila photoreceptors.

1990 ◽  
Vol 110 (6) ◽  
pp. 1993-1998 ◽  
Author(s):  
K Arikawa ◽  
J L Hicks ◽  
D S Williams
Keyword(s):  
Actin Filament ◽  
Brush Border ◽  
Actin Filaments ◽  
Immunogold Labeling ◽  
Entire Length ◽  
Filamentous Actin ◽  
Fast Growing ◽  
Intestinal Brush Border ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1

The phototransductive microvilli of arthropod photoreceptors each contain an axial cytoskeleton. The present study shows that actin filaments are a component of this cytoskeleton in Drosophila. Firstly, actin was detected in the rhabdomeral microvilli and in the subrhabdomeral cytoplasm by immunogold labeling with antiactin. Secondly, the rhabdomeres were labeled with phalloidin, indicating the presence of filamentous actin. Finally, the actin filaments were decorated with myosin subfragment-1. The characteristic arrowhead complex formed by subfragment-1 decoration points towards the base of the microvilli, so that the fast growing end of each filament is at the distal end of the microvillus, where it is embedded in a detergent-resistant cap. Each microvillus contains more than one actin filament. Decorated filaments extend the entire length of each microvillus and project into the subrhabdomeral cytoplasm. This organization is comparable to that of the actin filaments in intestinal brush border microvilli. Similar observations were made with the photoreceptor microvilli of the crayfish, Procambarus. Our results provide an indication as to how any myosin that is associated with the rhabdomeres might function.

Potential use of Si-labeled colloidal gold for localization of F-actin

1987 ◽  
Vol 45 ◽  
pp. 776-777
Author(s):  
J. J. Bozzola ◽  
R. N. Peterson ◽  
U. Kamaph ◽  
L. Russell ◽  
J. Shriver
Keyword(s):  
Colloidal Gold ◽  
Actin Filaments ◽  
Animal Species ◽  
Polyclonal Antibodies ◽  
Filamentous Actin ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
Decoration Technique ◽  
Antibody Specificities ◽  
Potential Use

Filamentous actin has been localized in numerous plant and animal species using various immunocytochemical procedures as well as a decoration technique using myosin subfragment 1 (SI). In the latter case, the long F-actin strands appear as herringbones with stacked arrowheads of SI pointing in the same direction. Unfortunately, when the actin filaments occur as shorter oligomers, it may be difficult to discern this pattern against a complex background. Using immunocytochemical procedures, variabilities in labeling patterns encountered may be attributed to the use of polyclonal antibodies or to antibody specificities for various subclasses of actin. In an attempt to localize short segments of F-actin without the use of antibodies, we labeled colloidal gold particles with purified SI.In order to evaluate the efficacy of this procedure, purified SI and partially purified F-actin were obtained from rabbit skeletal muscle.

scholarly journals Elongation of the fertilization tubule in Chlamydomonas: new observations on the core microfilaments and the effect of transient intracellular signals on their structural integrity.

1983 ◽  
Vol 97 (2) ◽  
pp. 522-532 ◽  
Author(s):  
P A Detmers ◽  
U W Goodenough ◽  
J Condeelis
Keyword(s):  
Mating Type ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Time Course ◽  
Structural Integrity ◽  
Cytochalasin D ◽  
Ultrastructural Observation ◽  
Intracellular Signals ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1

Experimental manipulations of gametes of Chlamydomonas reinhardi and ultrastructural observation were used to examine the composition of the microfilaments in the fertilization tubule, their probable mode of formation, and their interaction with intracellular signals. Decoration with myosin subfragment-1 was used to demonstrate that the microfilaments in the fertilization tubule were actin filaments having uniform polarity: Myosin subfragment-1 arrowheads pointed away from the membrane at the tip of the process. Filaments were attached to the cone-shaped "doublet zone" at the base of the process by their pointed ends. Discrete attachment sites for filaments on the surface of the doublet zone were seen in stereo view. To test whether actin polymerization might accompany elongation of the fertilization tubule, mating gametes were exposed to cytochalasin D in an attempt to block actin polymerization. Treatment of mating type "plus" gametes with cytochalasin D prior to and during mating inhibited the appearance of actin filaments in fertilization tubules, suppressed fertilization tubule outgrowth, and lowered mating efficiency from 90 to 15%. The role of signals generated by flagellar adhesion in maintaining the structural integrity of the microfilament-doublet zone complex was examined by correlating flagellar disadhesion with the kinetics of breakdown of the complex. In zygotes, where flagellar disadhesion occurred after cell fusion, the complex disassembled within 3 h after mating. In gametes that had been agglutinated by isolated mating type "minus" flagella, microfilaments and fertilization tubules progressively disassembled over a 3-h time course following flagellar disadhesion. Disassembly of microfilaments was inhibited by maintaining flagellar agglutination, suggesting that signals generated by flagellar adhesion were necessary to maintain microfilaments intact.

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