title: Dynactin increases the processivity of the cytoplasmic dynein motor.
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.
authors.affiliation: Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: King
authors.forename: T A
authors.initials: TA
authors.lastname: Schroer
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001665:Binding Sites / Q000502:physiology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002642:Chick Embryo; D003593:Cytoplasm / Q000201:enzymology; D000072159:Dynactin Complex; D004398:Dyneins / Q000276:immunology / Q000378:metabolism; D007700:Kinetics; D008863:Microspheres; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004398:Dyneins