title: De novo formation of basal bodies in Naegleria gruberi: regulation by phosphorylation.
abstract: The de novo formation of basal bodies in Naegleria gruberi was preceded by the transient formation of a microtubule (MT)-nucleating complex containing gamma-tubulin, pericentrin, and myosin II complex (GPM complex). The MT-nucleating activity of GPM complexes was maximal just before the formation of visible basal bodies and then rapidly decreased. The regulation of MT-nucleating activity of GPM complexes was accomplished by a transient phosphorylation of the complex. Inhibition of dephosphorylation after the formation of basal bodies resulted in the formation of multiple flagella. 2D-gel electrophoresis and Western blotting showed a parallel relationship between the MT-nucleating activity of GPM complexes and the presence of hyperphosphorylated gamma-tubulin in the complexes. These data suggest that the nucleation of MTs by GPM complexes precedes the de novo formation of basal bodies and that the regulation of MT-nucleating activity of GPM complexes is essential to the regulation of basal body number.
authors.affiliation: Department of Biology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Hong-Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Jeong-Gu
authors.initials: JG
authors.lastname: Kang
authors.forename: Shigehiko
authors.initials: S
authors.lastname: Yumura
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Walsh
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Cho
authors.forename: Joohun
authors.initials: J
authors.lastname: Lee
mesh_terms: D000818:Animals; D000941:Antigens / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005407:Flagella / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D046911:Macromolecular Substances; D022101:Microtubule-Organizing Center / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D024462:Myosin Type II / Q000378:metabolism; D009253:Naegleria / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D014404:Tubulin / Q000378:metabolism
chemical_list: D000941:Antigens; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D014404:Tubulin; C086178:pericentrin; D010744:Phosphoric Monoester Hydrolases; D024462:Myosin Type II