title: Dynein, dynactin, and kinesin II's interaction with microtubules is regulated during bidirectional organelle transport.
abstract: The microtubule motors, cytoplasmic dynein and kinesin II, drive pigmented organelles in opposite directions in Xenopus melanophores, but the mechanism by which these or other motors are regulated to control the direction of organelle transport has not been previously elucidated. We find that cytoplasmic dynein, dynactin, and kinesin II remain on pigment granules during aggregation and dispersion in melanophores, indicating that control of direction is not mediated by a cyclic association of motors with these organelles. However, the ability of dynein, dynactin, and kinesin II to bind to microtubules varies as a function of the state of aggregation or dispersion of the pigment in the cells from which these molecules are isolated. Dynein and dynactin bind to microtubules when obtained from cells with aggregated pigment, whereas kinesin II binds to microtubules when obtained from cells with dispersed pigment. Moreover, the microtubule binding activity of these motors/dynactin can be reversed in vitro by the kinases and phosphatase that regulate the direction of pigment granule transport in vivo. These findings suggest that phosphorylation controls the direction of pigment granule transport by altering the ability of dynein, dynactin, and kinesin II to interact with microtubules.
authors.affiliation: Department of Biology, University of California at Riverside, Riverside, California 92521, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Reese
authors.forename: L T
authors.initials: LT
authors.lastname: Haimo
mesh_terms: D000818:Animals; D001692:Biological Transport; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism; D016547:Kinesins; D008547:Melanophores; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009124:Muscle Proteins / Q000378:metabolism; D015388:Organelles / Q000502:physiology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010860:Pigments, Biological / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D012995:Solubility; D014981:Xenopus; D029867:Xenopus Proteins
chemical_list: D002135:Calcium-Binding Proteins; D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins; D009124:Muscle Proteins; D010860:Pigments, Biological; C499376:XKLP3 protein, Xenopus; D029867:Xenopus Proteins; C074152:kinesin-II; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; D004398:Dyneins; D016547:Kinesins