title: cdc25+ encodes a protein phosphatase that dephosphorylates p34cdc2.
abstract: To determine how the human cdc25 gene product acts to regulate p34cdc2 at the G2 to M transition, we have overproduced the full-length protein (cdc25Hs) as well as several deletion mutants in bacteria as glutathione-S-transferase fusion proteins. The wild-type cdc25Hs gene product was synthesized as an 80-kDa fusion protein (p80GST-cdc25) and was judged to be functional by several criteria: recombinant p80GST-cdc25 induced meiotic maturation of Xenopus oocytes in the presence of cycloheximide; p80GST-cdc25 activated histone H1 kinase activity upon addition to extracts prepared from Xenopus oocytes; p80GST-cdc25 activated p34cdc2/cyclin B complexes (prematuration promoting factor) in immune complex kinase assays performed in vitro; p80GST-cdc25 stimulated the tyrosine dephosphorylation of p34cdc2/cyclin complexes isolated from Xenopus oocyte extracts as well as from overproducing insect cells; and p80GST-cdc25 hydrolyzed p-nitrophenylphosphate. In addition, deletion analysis defined a functional domain residing within the carboxy-terminus of the cdc25Hs protein. Taken together, these results suggest that the cdc25Hs protein is itself a phosphatase and that it may function directly in the tyrosine dephosphorylation and activation of p34cdc2 at the G2 to M transition.
authors.affiliation: Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
authors.forename: M S
authors.initials: MS
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Ogg
authors.forename: M
authors.initials: M
authors.lastname: Xu
authors.forename: L L
authors.initials: LL
authors.lastname: Parker
authors.forename: D J
authors.initials: DJ
authors.lastname: Donoghue
authors.forename: J L
authors.initials: JL
authors.lastname: Maller
authors.forename: H
authors.initials: H
authors.lastname: Piwnica-Worms
mesh_terms: D000818:Animals; D001483:Base Sequence; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002460:Cell Line; D005982:Glutathione Transferase / Q000378:metabolism; D016200:Maturation-Promoting Factor / Q000502:physiology; D008540:Meiosis; D008969:Molecular Sequence Data; D009596:Nitrophenols / Q000378:metabolism; D009865:Oocytes / Q000502:physiology; D009943:Organophosphorus Compounds / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D014981:Xenopus; D020687:cdc25 Phosphatases
chemical_list: D009596:Nitrophenols; D009943:Organophosphorus Compounds; D011506:Proteins; D011993:Recombinant Fusion Proteins; C008644:nitrophenylphosphate; D014443:Tyrosine; D005982:Glutathione Transferase; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor; D010749:Phosphoprotein Phosphatases; D020687:cdc25 Phosphatases