title: Dephosphorylation of the inhibitory phosphorylation site S287 in Xenopus Cdc25C by protein phosphatase-2A is inhibited by 14-3-3 binding.
abstract: Cdc25C phosphatase induces mitosis by dephosphorylating and activating Cdc2/cyclin B protein kinase. Phosphorylation of Xenopus Cdc25C at serine 287 creates a binding site for a 14-3-3 protein and restrains activation during interphase. Here, we show that dephosphorylation of S287 is catalysed by protein phosphatase-2A in Xenopus egg extracts. 14-3-3 protein binding to Cdc25C inhibits dephosphorylation of S287, providing a mechanism to maintain phosphorylation of that site during interphase. The rate of dephosphorylation of S287 is not increased in mitotic extracts, indicating that the phosphorylation status of the site is likely to be controlled through modulation of kinases or 14-3-3 binding activity.
authors.affiliation: Biomedical Research Centre, Level 5, Ninewells Hospital and Medical School, University of Dundee, UK.
authors.forename: James R A
authors.initials: JR
authors.lastname: Hutchins
authors.forename: Dina
authors.initials: D
authors.lastname: Dikovskaya
authors.forename: Paul R
authors.initials: PR
authors.lastname: Clarke
mesh_terms: D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D007399:Interphase; D008938:Mitosis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*; D014981:Xenopus / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D018797:Cell Cycle Proteins; D011993:Recombinant Fusion Proteins; D012694:Serine; D014446:Tyrosine 3-Monooxygenase; D016203:CDC2 Protein Kinase; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D020687:cdc25 Phosphatases