title: Interaction of CK1δ with γTuSC ensures proper microtubule assembly and spindle positioning.
abstract: Casein kinase 1δ (CK1δ) family members associate with microtubule-organizing centers (MTOCs) from yeast to humans, but their mitotic roles and targets have yet to be identified. We show here that budding yeast CK1δ, Hrr25, is a γ-tubulin small complex (γTuSC) binding factor. Moreover, Hrr25's association with γTuSC depends on its kinase activity and its noncatalytic central domain. Loss of Hrr25 kinase activity resulted in assembly of unusually long cytoplasmic microtubules and defects in spindle positioning, consistent with roles in regulation of γTuSC-mediated microtubule nucleation and the Kar9 spindle-positioning pathway, respectively. Hrr25 directly phosphorylated γTuSC proteins in vivo and in vitro, and this phosphorylation promoted γTuSC integrity and activity. Because CK1δ and γTuSC are highly conserved and present at MTOCs in diverse eukaryotes, similar regulatory mechanisms are expected to apply generally in eukaryotes.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720.
authors.forename: Yutian
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158.
authors.forename: Michelle
authors.initials: M
authors.lastname: Moritz
authors.affiliation: Department of Chemical Physiology, Scripps Research Institute, La Jolla, CA 92037.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Han
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, CO 80309.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Giddings
authors.affiliation: Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lyon
authors.affiliation: Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158.
authors.forename: Justin
authors.initials: J
authors.lastname: Kollman
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, CO 80309.
authors.forename: Mark
authors.initials: M
authors.lastname: Winey
authors.affiliation: Department of Chemical Physiology, Scripps Research Institute, La Jolla, CA 92037.
authors.forename: John
authors.initials: J
authors.lastname: Yates
authors.affiliation: Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158.
authors.forename: David A
authors.initials: DA
authors.lastname: Agard
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 gbarnes@berkeley.edu drubin@berkeley.edu.
authors.forename: David G
authors.initials: DG
authors.lastname: Drubin
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 gbarnes@berkeley.edu drubin@berkeley.edu.
authors.forename: Georjana
authors.initials: G
authors.lastname: Barnes
mesh_terms: D047389:Casein Kinase I / Q000378:metabolism; D048148:Casein Kinase Idelta / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D003599:Cytoskeleton / Q000378:metabolism; D022101:Microtubule-Organizing Center / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D010766:Phosphorylation; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D004718:Saccharomycetales / Q000166:cytology / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D014404:Tubulin; D047389:Casein Kinase I; D048148:Casein Kinase Idelta; C070775:HRR25 protein, S cerevisiae