Specificity and orientation of (iodoacetamido)proxyl spin-labeled myosin subfragment 1 decorating muscle fibers: localization of protein-bound spin labels using SDS-PAGE

Biochemistry ◽  
1990 ◽  
Vol 29 (33) ◽  
pp. 7733-7741 ◽  
Author(s):  
Katalin Ajtai ◽  
Laszlo Poto ◽  
Thomas P. Burghardt
1980 ◽  
Vol 58 (7) ◽  
pp. 797-801 ◽  
Author(s):  
Maryanne Vahey ◽  
Stylianos P. Scordilis

Proteins exhibiting all of the basic structural and biochemical characteristics of actin and myosin have been isolated from the parenchymal cells of the fruit of the tomato, Lycopersicon esculentum. Crude cytoplasmic extracts of these cells contain filaments that can be decorated by rabbit skeletal muscle myosin subfragment-1 (S-1). Polymerized tomato actin activates the Mg2+–ATPase of both skeletal and tomato myosin at physiological ionic strength. Tomato actin comigrates with skeletal actin on sodium dodecyl sulfate polyacrylamide gels (SDS-PAGE) indicating an apparent molecular weight of 45 000. High ionic strength extracts of tomato contain a myosin whose ATPase activity in 0.5 M KCl is maximal in the presence of K+-ethylenediaminetetraacetic acid (K+-EDTA) and is inhibited by Mg2+. Tomato myosin interacts with skeletal F-actin to form an actomyosin complex that can be dissociated by ATP. At low ionic strength the Mg2+–ATPase of the myosin can be activated by actin.


1982 ◽  
Vol 95 (1) ◽  
pp. 310-315 ◽  
Author(s):  
K Owaribe ◽  
H Masuda

Chicken retinal pigmented epithelial cells have circumferential microfilament bundles (CMBs) at the zonula adherens region. We have isolated these CMBs in intact form and characterized them structurally and biochemically. Pigmented epithelia obtained from 11-d-old chick embryos were treated with glycerol and Triton. Then, the epithelia were homogenized by passing them through syringe needles. Many isolated CMBs were found in the homogenate by phase-contrast microscopy. They formed polygons, mostly pentagons and hexagons, or fragments of polygons. Polygons were filled with meshwork structures, i.e. they were polygonal plates. Upon exposure to Mg-ATP, isolated CMBs showed clear and large contraction. The contraction was inhibited by treatment with N-ethylmaleimide-modified myosin subfragment-1. After purification by centrifugation with the density gradient of Percoll, CMBs were analyzed by SDS PAGE. The electrophoretic pattern gave three major components of 200, 55, and 42 kdaltons and several minor components. Electron microscopy showed that the polygons were composed of thick bundles of actin-containing microfilaments, and the meshworks were composed primarily of intermediate filaments.


2003 ◽  
Vol 43 (supplement) ◽  
pp. S129
Author(s):  
H. Iwamoto ◽  
T. Uyeda ◽  
E. Katayama ◽  
J. Wakayama ◽  
T. Tamura ◽  
...  

Author(s):  
Donald A. Winkelmann

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.


1989 ◽  
Vol 264 (18) ◽  
pp. 10810-10819
Author(s):  
K N Rajasekharan ◽  
M Mayadevi ◽  
M Burke

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