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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
4
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pubmed:dateCreated |
2004-3-25
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pubmed:abstractText |
It is well documented that muscle contraction results from cyclic rotations of actin-bound myosin cross-bridges. The role of actin is hypothesized to be limited to accelerating phosphate release from myosin and to serving as a rigid substrate for cross-bridge rotations. To test this hypothesis, we have measured actin rotations during contraction of a skeletal muscle. Actin filaments of rabbit psoas fiber were labeled with rhodamine-phalloidin. Muscle contraction was induced by a pulse of ATP photogenerated from caged precursor. ATP induced a single turnover of cross-bridges. The rotations were measured by anisotropy of fluorescence originating from a small volume defined by a narrow aperture of a confocal microscope. The anisotropy of phalloidin-actin changed rapidly at first and was followed by a slow relaxation to a steady-state value. The kinetics of orientation changes of actin and myosin were the same. Extracting myosin abolished anisotropy changes. To test whether the rotation of actin was imposed by cross-bridges or whether it reflected hydrolytic activity of actin itself, we labeled actin with fluorescent ADP. The time-course of anisotropy change of fluorescent nucleotide was similar to that of phalloidin-actin. These results suggest that orientation changes of actin are caused by dissociation and rebinding of myosin cross-bridges, and that during contraction, nucleotide does not dissociate from actin.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-10585941,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-11294650,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-11602582,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-12023239,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-12668452,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-1531296,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-1651780,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-230351,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-263688,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-4132695,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-470613,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-4939977,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-572853,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-6266539,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-9258508,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-9635762,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15041669-9726945
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0006-3495
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
86
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2308-17
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pubmed:dateRevised |
2009-11-19
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pubmed:meshHeading |
pubmed-meshheading:15041669-Actins,
pubmed-meshheading:15041669-Adenosine Triphosphate,
pubmed-meshheading:15041669-Animals,
pubmed-meshheading:15041669-Fluorescent Dyes,
pubmed-meshheading:15041669-Microscopy, Confocal,
pubmed-meshheading:15041669-Muscle, Skeletal,
pubmed-meshheading:15041669-Muscle Contraction,
pubmed-meshheading:15041669-Myosins,
pubmed-meshheading:15041669-Phalloidine,
pubmed-meshheading:15041669-Rabbits
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pubmed:year |
2004
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pubmed:articleTitle |
Changes in orientation of actin during contraction of muscle.
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pubmed:affiliation |
Department of Molecular Biology and Immunology, University of North Texas, Fort Worth, Texas, USA. jborejdo@hsc.unt.edu
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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