Abstract
Cytoplasmic dynein supports long-range intracellular movements of cargo in vivo but does not appear to be a processive motor protein by itself. We show here that the dynein activator, dynactin, binds microtubules and increases the average length of cytoplasmic-dynein-driven movements without affecting the velocity or microtubule-stimulated ATPase kinetics of cytoplasmic dynein. Enhancement of microtubule binding and motility by dynactin are both inhibited by an antibody to dynactin's microtubule-binding domain. These results indicate that dynactin acts as a processivity factor for cytoplasmic-dynein-based motility and provide the first evidence that cytoskeletal motor processivity can be affected by extrinsic factors.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenosine Triphosphatases / metabolism
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Adenosine Triphosphate / metabolism
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Adenosine Triphosphate / pharmacology
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Animals
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Antibodies / pharmacology
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Binding Sites / physiology
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Biological Transport / drug effects
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Biological Transport / physiology
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Chick Embryo
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Cytoplasm / enzymology
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Dynactin Complex
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Dyneins / immunology
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Dyneins / metabolism
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Kinetics
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Microspheres
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Microtubule-Associated Proteins / chemistry
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Microtubule-Associated Proteins / immunology
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Microtubule-Associated Proteins / metabolism*
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Microtubules / chemistry
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Microtubules / metabolism*
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Molecular Motor Proteins / chemistry
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Molecular Motor Proteins / immunology
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Molecular Motor Proteins / metabolism*
Substances
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Antibodies
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Dynactin Complex
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Microtubule-Associated Proteins
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Molecular Motor Proteins
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Adenosine Triphosphate
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Adenosine Triphosphatases
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Dyneins