title: Greatwall kinase and cyclin B-Cdk1 are both critical constituents of M-phase-promoting factor.
abstract: Maturation/M-phase-promoting factor is the universal inducer of M-phase in eukaryotic cells. It is currently accepted that M-phase-promoting factor is identical to the kinase cyclin B-Cdk1. Here we show that cyclin B-Cdk1 and M-phase-promoting factor are not in fact synonymous. Instead, M-phase-promoting factor contains at least two essential components: cyclin B-Cdk1 and another kinase, Greatwall kinase. In the absence of Greatwall kinase, the M-phase-promoting factor is undetectable in oocyte cytoplasm even though cyclin B-Cdk1 is fully active, whereas M-phase-promoting factor activity is restored when Greatwall kinase is added back. Although the excess amount of cyclin B-Cdk1 alone, but not Greatwall kinase alone, can induce nuclear envelope breakdown, spindle assembly is abortive. Addition of Greatwall kinase greatly reduces the amount of cyclin B-Cdk1 required for nuclear envelope breakdown, resulting in formation of the spindle with aligned chromosomes. M-phase-promoting factor is thus a system consisting of one kinase (cyclin B-Cdk1) that directs mitotic entry and a second kinase (Greatwall kinase) that suppresses the protein phosphatase 2A-B55 which opposes cyclin B-Cdk1.
authors.affiliation: Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hara
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Abe
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tanaka
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Eiichi
authors.initials: E
authors.lastname: Okumura
authors.forename: Takeo
authors.initials: T
authors.lastname: Kishimoto
mesh_terms: D000818:Animals; D047288:Asterina / Q000166:cytology / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism*; D005260:Female; D016200:Maturation-Promoting Factor / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D019926:Cyclin B; D029867:Xenopus Proteins; C544010:MASTL protein, Xenopus; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor