Abstract
Factors that are involved in actin polymerization, such as the Arp2/3 complex, have been found to be packaged into discrete, motile, actin-rich foci. Here we investigate the mechanism of actin-patch motility in S. pombe using a fusion of green fluorescent protein (GFP) to a coronin homologue, Crn1p. Actin patches are associated with cables and move with rates of 0.32 microm s(-1) primarily in an undirected manner at cell tips and also in a directed manner along actin cables, often away from cell tips. Patches move more slowly or stop when actin polymerization is attenuated by Latrunculin A or in arp3 and cdc3 (profilin) mutants. In a cdc8 (tropomyosin) mutant, actin cables are absent, and patches move with similar speed but in a non-directed manner. Patches are sites of Arp3-dependent F-actin polymerization in vitro. Rapid F-actin turnover rates in vivo indicate that patches and cables are maintained continuously by actin polymerization. Our studies give rise to a model in which actin patches are centres for actin polymerization that drive their own movement on actin cables using Arp2/3-based actin polymerization.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actin-Related Protein 2
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Actin-Related Protein 3
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Actins / metabolism*
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Bridged Bicyclo Compounds, Heterocyclic / pharmacology
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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Contractile Proteins*
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Cytoskeletal Proteins*
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Cytoskeleton / metabolism*
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Fluorescent Dyes / metabolism
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Genes, Reporter
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Green Fluorescent Proteins
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Kinetics
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Microfilament Proteins / genetics
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Microfilament Proteins / metabolism
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Microscopy, Confocal
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Microscopy, Video
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Polymers / metabolism
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Profilins
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Schizosaccharomyces / genetics
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Schizosaccharomyces / physiology*
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Schizosaccharomyces pombe Proteins*
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Temperature
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Thiazoles / pharmacology
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Thiazolidines
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Time Factors
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Tropomyosin / metabolism
Substances
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Actin-Related Protein 2
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Actin-Related Protein 3
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Actins
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Bridged Bicyclo Compounds, Heterocyclic
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Cdc8 protein, S pombe
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Cell Cycle Proteins
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Contractile Proteins
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Cytoskeletal Proteins
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Fluorescent Dyes
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Luminescent Proteins
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Microfilament Proteins
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Polymers
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Profilins
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Recombinant Fusion Proteins
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Schizosaccharomyces pombe Proteins
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Thiazoles
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Thiazolidines
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Tropomyosin
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cdc3 protein, S pombe
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coronin proteins
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Green Fluorescent Proteins
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latrunculin A