title: Dephosphorylation and activation of a p34cdc2/cyclin B complex in vitro by human CDC25 protein.
abstract: Oocytes arrested in the G2 phase of the cell cycle contain a p34cdc2/cyclin B complex which is kept in an inactive form by phosphorylation of its p34cdc2 subunit on tyrosine, threonine and perhaps serine residues. The phosphatase(s) involved in p34cdc2 dephosphorylation is unknown, but the product of the fission yeast cdc25+ gene, and its homologues in budding yeast and Drosophila are probably positive regulators of the transition from G2 to M phase. We have purified the inactive p34cdc2/cyclin B complex from G2-arrested starfish oocytes. Addition of the purified bacterially expressed product of the human homologue of the fission yeast cdc25+ gene (p54CDC25H) triggers p34cdc2 dephosphorylation and activates H1 histone kinase activity in this preparation. We propose that the cdc25+ gene product directly activates the p34cdc2-cyclin B complex.
authors.affiliation: CNRS and INSERM, BP 5051, Montpellier, France.
authors.forename: U
authors.initials: U
authors.lastname: Strausfeld
authors.forename: J C
authors.initials: JC
authors.lastname: Labbé
authors.forename: D
authors.initials: D
authors.lastname: Fesquet
authors.forename: J C
authors.initials: JC
authors.lastname: Cavadore
authors.forename: A
authors.initials: A
authors.lastname: Picard
authors.forename: K
authors.initials: K
authors.lastname: Sadhu
authors.forename: P
authors.initials: P
authors.lastname: Russell
authors.forename: M
authors.initials: M
authors.lastname: Dorée
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D016213:Cyclins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005786:Gene Expression Regulation; D066298:In Vitro Techniques; D016200:Maturation-Promoting Factor / Q000096:biosynthesis; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011506:Proteins / Q000494:pharmacology*; D013215:Starfish; D014162:Transfection; D020687:cdc25 Phosphatases
chemical_list: D016213:Cyclins; D011506:Proteins; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor; D020687:cdc25 Phosphatases