title: Association of p34cdc2/cyclin B complex with microtubules in starfish oocytes.
abstract: The microtubular cytoskeleton exhibits a dramatic reorganization, progressing from interphase radial arrays to a mitotic spindle at the G2/M transition. Although this reorganization has been suspected to be caused by maturation promoting factor (MPF: p34cdc2/cyclin B complex), little is known about how p34cdc2 kinase controls microtubule networks. We provide evidence of the direct association of the p34cdc2/cyclin B complex with microtubules in starfish oocytes. Anti-cyclin B staining of detergent-treated oocytes, isolated asters and meiotic spindles revealed fluorescence associated with microtubule fibers, chromosomes and centrosomes. Microtubules prepared from starfish oocytes were associated with cyclin B and p34cdc2 proteins. Microtubule-bound p34cdc2 and cyclin B were released from microtubules by a high-salt solution and possessed a complex form as shown by the adsorption to suc1-beads and by immunoprecipitation with the anti-cyclin B antibody. The p34cdc2/cyclin B complex associated to microtubules had high histone H1 kinase activity at meiotic metaphase. However, it was not necessary for the p34cdc2/cyclin B complex to be active for microtubule binding, as an inactive form in immature oocytes was also observed to bind to microtubules. The coprecipitation of suc1-column purified p34cdc2/cyclin B with purified porcine brain microtubules in the presence of starfish oocyte microtubule-associated proteins (MAPs) indicates that the association of p34cdc2/cyclin B with microtubules in vitro is mediated by MAPs.
authors.affiliation: Laboratory of Cell and Developmental Biology, Faculty of Biosciences, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ookata
authors.forename: S
authors.initials: S
authors.lastname: Hisanaga
authors.forename: E
authors.initials: E
authors.lastname: Okumura
authors.forename: T
authors.initials: T
authors.lastname: Kishimoto
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D008540:Meiosis; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D013215:Starfish / Q000378:metabolism; D013379:Substrate Specificity; D013552:Swine; D014404:Tubulin / Q000378:metabolism
chemical_list: D016213:Cyclins; D008869:Microtubule-Associated Proteins; D014404:Tubulin; D016203:CDC2 Protein Kinase