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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
34
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pubmed:dateCreated |
1987-1-7
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pubmed:abstractText |
Fluorescence changes using actin covalently labeled with N-(1-pyrenyl)iodoacetamide have been used to determine the effect of cytochalasin D on actin polymerization. A mechanism for the effect of cytochalasin D on actin polymerization is presented, which explains the experimental observation of a cytochalasin D-induced increase in the initial rate of polymerization and a decrease in the final extent of the reaction. Central to this mechanism is the Mg2+-dependent formation of cytochalasin D-induced dimers. The dimers serve as nuclei to enhance the polymerization rate. Binding of Mg2+ to a low affinity site on the dimer induces a conformational change which can be observed as a rapid fluorescence increase. A subsequent time-dependent fluorescence decrease observed prior to polymerization appears to represent ATP hydrolysis resulting in dissociation of the dimer and release of actin monomers containing ADP. We postulate that a slow rate of exchange of ATP for bound ADP relative to hydrolysis results in the accumulation of monomers containing ADP. As these monomers have a high critical concentration, the final extent of polymerization is reduced dramatically. The Mg2+ dependence of the final extent of polymerization in the presence of cytochalasin D is also explained in the context of this mechanism.
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pubmed:grant |
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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 |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
5
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pubmed:volume |
261
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
15974-80
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:3023337-Actins,
pubmed-meshheading:3023337-Adenosine Diphosphate,
pubmed-meshheading:3023337-Adenosine Triphosphate,
pubmed-meshheading:3023337-Calcium-Binding Proteins,
pubmed-meshheading:3023337-Cytochalasin D,
pubmed-meshheading:3023337-Cytochalasins,
pubmed-meshheading:3023337-Dose-Response Relationship, Drug,
pubmed-meshheading:3023337-Fluorescence,
pubmed-meshheading:3023337-Gelsolin,
pubmed-meshheading:3023337-Hydrolysis,
pubmed-meshheading:3023337-Kinetics,
pubmed-meshheading:3023337-Magnesium,
pubmed-meshheading:3023337-Microfilament Proteins,
pubmed-meshheading:3023337-Polymers,
pubmed-meshheading:3023337-Protein Conformation,
pubmed-meshheading:3023337-Time Factors
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pubmed:year |
1986
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pubmed:articleTitle |
Actin polymerization. The mechanism of action of cytochalasin D.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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