Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
In Xenopus embryos, the cell cycle is abbreviated to a rapid alternation between interphase and mitosis. The onset of each M phase is induced by the periodic activation of the cdc2 kinase which is triggered by a threshold level of cyclins and apparently involves dephosphorylation of p34cdc2. We have prepared post-ribosomal supernatants from eggs sampled during interphase (interphase extracts) and just before the first mitosis of the early embryonic cell cycle (prophase extracts). In 'interphase extracts', the cdc2 kinase never activates spontaneously upon incubation at room temperature whereas in 'prophase extracts' it does. We show here that in 'interphase extracts', specific inhibition of type 2A phosphatase by okadaic acid induces cdc2 kinase activation. This requires a subthreshold level of cyclin and the presence of a particulate factor in the extract. Inhibition of type 1 phosphatases by inhibitor 1 and inhibitor 2 never results in cdc2 kinase activation. These results demonstrate that during the period of cyclin accumulation, cdc2 kinase activation is inhibited by a type 2A phosphatase. In 'prophase extracts', spontaneous activation of the cdc2 kinase is inhibited by beta-glycerophosphate and NaF, but not by okadaic acid, inhibitor 1 and inhibitor 2 or divalent cation chelation. This demonstrates that when enough cyclin has accumulated, cdc2 kinase activation involves a protein phosphatase which must be distinct from the type 1 and 2A phosphatases, and from the calcium-dependent (type 2B) and magnesium-dependent (type 2C) phosphatases.
Arion,
cdc2 is a component of the M phase-specific histone H1 kinase: evidence for identity with MPF.
1988, Pubmed,
Xenbase
Arion,
cdc2 is a component of the M phase-specific histone H1 kinase: evidence for identity with MPF.
1988,
Pubmed
,
Xenbase Beach,
Functionally homologous cell cycle control genes in budding and fission yeast.
1982,
Pubmed Bialojan,
Inhibitory effect of a marine-sponge toxin, okadaic acid, on protein phosphatases. Specificity and kinetics.
1988,
Pubmed Booher,
Involvement of a type 1 protein phosphatase encoded by bws1+ in fission yeast mitotic control.
1989,
Pubmed Booher,
The fission yeast cdc2/cdc13/suc1 protein kinase: regulation of catalytic activity and nuclear localization.
1989,
Pubmed Brizuela,
p13suc1 acts in the fission yeast cell division cycle as a component of the p34cdc2 protein kinase.
1987,
Pubmed Brizuela,
Activation of human CDC2 protein as a histone H1 kinase is associated with complex formation with the p62 subunit.
1989,
Pubmed Cohen,
An improved procedure for identifying and quantitating protein phosphatases in mammalian tissues.
1989,
Pubmed Cohen,
Protein phosphatase-1 and protein phosphatase-2A from rabbit skeletal muscle.
1988,
Pubmed Cohen,
The structure and regulation of protein phosphatases.
1989,
Pubmed Cohen,
Protein phosphatases come of age.
1989,
Pubmed Cyert,
Regulation of MPF activity in vitro.
1988,
Pubmed
,
Xenbase da Cruz e Silva,
Identification of a novel protein phosphatase catalytic subunit by cDNA cloning.
1988,
Pubmed da Cruz e Silva,
A second catalytic subunit of type-2A protein phosphatase from rabbit skeletal muscle.
1987,
Pubmed Doonan,
The bimG gene of Aspergillus nidulans, required for completion of anaphase, encodes a homolog of mammalian phosphoprotein phosphatase 1.
1989,
Pubmed Draetta,
Activation of cdc2 protein kinase during mitosis in human cells: cell cycle-dependent phosphorylation and subunit rearrangement.
1988,
Pubmed Dunphy,
Fission yeast p13 blocks mitotic activation and tyrosine dephosphorylation of the Xenopus cdc2 protein kinase.
1989,
Pubmed
,
Xenbase Dunphy,
The Xenopus cdc2 protein is a component of MPF, a cytoplasmic regulator of mitosis.
1988,
Pubmed
,
Xenbase Evans,
Cyclin: a protein specified by maternal mRNA in sea urchin eggs that is destroyed at each cleavage division.
1983,
Pubmed Felix,
A post-ribosomal supernatant from activated Xenopus eggs that displays post-translationally regulated oscillation of its cdc2+ mitotic kinase activity.
1989,
Pubmed
,
Xenbase Foulkes,
In vivo actions of protein phosphatase inhibitor-2 in Xenopus oocytes.
1982,
Pubmed
,
Xenbase Gautier,
Purified maturation-promoting factor contains the product of a Xenopus homolog of the fission yeast cell cycle control gene cdc2+.
1988,
Pubmed
,
Xenbase Gautier,
Dephosphorylation and activation of Xenopus p34cdc2 protein kinase during the cell cycle.
1989,
Pubmed
,
Xenbase Goris,
Okadaic acid, a specific protein phosphatase inhibitor, induces maturation and MPF formation in Xenopus laevis oocytes.
1989,
Pubmed
,
Xenbase Gould,
Tyrosine phosphorylation of the fission yeast cdc2+ protein kinase regulates entry into mitosis.
1989,
Pubmed Haystead,
Effects of the tumour promoter okadaic acid on intracellular protein phosphorylation and metabolism.
1989,
Pubmed Huchon,
Protein phosphatase-1 is involved in Xenopus oocyte maturation.
1981,
Pubmed
,
Xenbase Karsenti,
Phosphorylation changes associated with the early cell cycle in Xenopus eggs.
1987,
Pubmed
,
Xenbase Labbe,
Purification of MPF from starfish: identification as the H1 histone kinase p34cdc2 and a possible mechanism for its periodic activation.
1989,
Pubmed
,
Xenbase Labbe,
Activation at M-phase of a protein kinase encoded by a starfish homologue of the cell cycle control gene cdc2+.
1988,
Pubmed
,
Xenbase Labbé,
MPF from starfish oocytes at first meiotic metaphase is a heterodimer containing one molecule of cdc2 and one molecule of cyclin B.
1989,
Pubmed Labbé,
An M-phase-specific protein kinase of Xenopus oocytes: partial purification and possible mechanism of its periodic activation.
1988,
Pubmed
,
Xenbase Maller,
Regulation of amphibian oocyte maturation.
1985,
Pubmed
,
Xenbase McGowan,
Protein phosphatase-2C from rabbit skeletal muscle and liver: an Mg2+-dependent enzyme.
1988,
Pubmed Meijer,
Cyclin is a component of the sea urchin egg M-phase specific histone H1 kinase.
1989,
Pubmed Meijer,
Protein phosphorylation and oocyte maturation. II. Inhibition of starfish oocyte maturation by intracellular microinjection of protein phosphatases 1 and 2A and alkaline phosphatase.
1986,
Pubmed Minshull,
Translation of cyclin mRNA is necessary for extracts of activated xenopus eggs to enter mitosis.
1989,
Pubmed
,
Xenbase Moreno,
Regulation of p34cdc2 protein kinase during mitosis.
1989,
Pubmed Morla,
Reversible tyrosine phosphorylation of cdc2: dephosphorylation accompanies activation during entry into mitosis.
1989,
Pubmed Murray,
Cyclin synthesis drives the early embryonic cell cycle.
1989,
Pubmed
,
Xenbase Murray,
The role of cyclin synthesis and degradation in the control of maturation promoting factor activity.
1989,
Pubmed
,
Xenbase Nurse,
Gene required in G1 for commitment to cell cycle and in G2 for control of mitosis in fission yeast.
1981,
Pubmed Ohkura,
The fission yeast dis2+ gene required for chromosome disjoining encodes one of two putative type 1 protein phosphatases.
1989,
Pubmed Picard,
Involvement of protein phosphatases 1 and 2A in the control of M phase-promoting factor activity in starfish.
1989,
Pubmed Picard,
Role of protein synthesis and proteases in production and inactivation of maturation-promoting activity during meiotic maturation of starfish oocytes.
1985,
Pubmed Pines,
Molecular cloning and characterization of the mRNA for cyclin from sea urchin eggs.
1987,
Pubmed
,
Xenbase Pines,
Isolation of a human cyclin cDNA: evidence for cyclin mRNA and protein regulation in the cell cycle and for interaction with p34cdc2.
1989,
Pubmed Russell,
The mitotic inducer nim1+ functions in a regulatory network of protein kinase homologs controlling the initiation of mitosis.
1987,
Pubmed Simanis,
The cell cycle control gene cdc2+ of fission yeast encodes a protein kinase potentially regulated by phosphorylation.
1986,
Pubmed Stewart,
The MgATP-dependent protein phosphatase and protein phosphatase 1 have identical substrate specificities.
1981,
Pubmed
