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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
3
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pubmed:dateCreated |
1980-3-17
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pubmed:abstractText |
The contracted pellets derived from a high-speed supernate of Dictyostelium discoideum (S3) were investigated to determine the functional activity associated with this specific subset of the cellular motile apparatus. A partially purified model system of gelation and contraction (S6) was prepared from the contracted pellets, and the presence of calcium- and pH-sensitive gelation and contraction in this model demonstrated that a functional cytoskeletal-contratile complex remained at least partially associated with the actin and myosin during contraction. Semi-quantitative assays of gelation and solation in the myosin-free preparation S6 included measurements of turbidity, relative viscosity, and strain birefringence. The extent of gelation was optimal at pH 6.8 and a free calcium ion concentration of approximately 3.0 x 10(-8) M. Solation was favored when the free calcium ion concentration was greater than 7.6 x 10(-7) M or when the pH was increased or decreased from pH 6.8. Gelation was reversibly inhibited by increasing the free calcium ion concentration to approxomately 4.6 x 10(-6) M at pH 6.8. The solation-gelation process of this model has been interpreted to involve the reversible cross-linking of actin filaments. The addition of purified D. discoideum myosin to S6 served to reconstitute calcium- and pH-regulated contraction. The results from this study indicate that contraction is coupled functionally to the local breakdown (solation) of the gel. Therefore, solation has been identified as a structural requirement for extensive shortening during contraction. We have called this concept the solation-contraction coupling hypothesis. Fractionation of a preparation derived from the contracted pellets yielded a fraction consisting of actin and a 95,000-dalton polypeptide that exhibited calcium-sensitive gelation at 28 degrees C and a fraction composed of actin and 30,000- and 18,000-dalton polypeptides that demonstrated calcium-sensitive genlation at 0 degrees C.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-1030705,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-1033188,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-1035911,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-1142428,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-1172503,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-131790,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-133352,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-137899,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-141454,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-143236,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-14907713,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-19555,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-204423,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-20447,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-23862,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-37189,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-4115981,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-4254541,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-4278009,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-4280006,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-4805006,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-5063250,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-53835,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-5432063,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-568144,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-629790,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-6480,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-721823,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-799215,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-844506,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-972388,
http://linkedlifedata.com/resource/pubmed/commentcorrection/42649-987247
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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 |
Dec
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pubmed:issn |
0021-9525
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
83
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
633-48
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pubmed:dateRevised |
2009-11-19
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pubmed:meshHeading |
pubmed-meshheading:42649-Calcium,
pubmed-meshheading:42649-Contractile Proteins,
pubmed-meshheading:42649-Cytoplasmic Streaming,
pubmed-meshheading:42649-Cytoskeleton,
pubmed-meshheading:42649-Dictyostelium,
pubmed-meshheading:42649-Gels,
pubmed-meshheading:42649-Hydrogen-Ion Concentration,
pubmed-meshheading:42649-Models, Biological,
pubmed-meshheading:42649-Myosins,
pubmed-meshheading:42649-Viscosity
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pubmed:year |
1979
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pubmed:articleTitle |
The contractile basis of ameboid movement. VI. The solation-contraction coupling hypothesis.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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