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Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cdc2 gene product, a 34-kDa phosphoprotein with serine/threonine protein kinase activity, has been implicated as the key component in the regulation of the eucaryotic cell cycle. Activation of the cdc2 protein kinase is regulated by its phosphorylation state and by interaction with other proteins. We have mutagenized the fission yeast cdc2 gene to obtain conditionally dominant negative alleles. One of these mutants, named DL2, is characterized in this report. Overexpression of the mutant protein in a wild-type cdc2 background is lethal and leads to arrest in the G2 phase of the cell cycle. The mutant phenotype is the result of a single amino acid change in the GDSEID motif of the protein, a region of identity in all cdc2 homologs, and results in a nonfunctional protein that shows an altered content of phosphothreonine. Multicopy suppressors of the dominant negative phenotype have been isolated, and one of these has been shown to encode the cdc13 cyclin B gene product.
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PMID:A dominant negative allele of p34cdc2 shows altered phosphoamino acid content and sequesters p56cdc13 cyclin. 153 72

Numatrin is a nuclear matrix phosphoprotein whose synthesis and abundance were shown to be regulated during the cell cycle in mitogen-stimulated lymphocytes (Feuerstein, N., and Mond, J. (1987) J. Biol. Chem. 262, 11389-11397). We examined the effect of (a) CTD-kinase, which contains the cdc2 catalytic component (p34) in a complex with a p58 subunit (cdc2/p58) and (b) the M phase-specific histone H1 kinase, which contains the cdc2 kinase in association with a p62 subunit (cdc2/p62), on phosphorylation of numatrin. We show that both cdc2 kinase complexes can phosphorylate numatrin. However, cdc2/p58 at conditions that caused a similar effect to cdc2/p62 on phosphorylation of histone H1 (dpm/micrograms of substrate/micrograms of enzyme) was found to have a 5-25-fold higher catalytic activity in the phosphorylation of numatrin. Analysis of the tryptic phosphopeptide map of numatrin phosphorylated by these cdc2 kinase complexes showed that both kinase complexes phosphorylated two major identical peptides, but minor additional peptides were differentially phosphorylated by each of these kinases. This indicates that under certain experimental conditions cdc2/p58 and cdc2/p62 may express some differences in their catalytic activity. In vitro phosphorylation by CTD kinase of a whole nuclear protein extract from murine fibroblasts showed that numatrin is the most prominent substrate for CTD kinase in this nuclear extract. CTD kinase cdc2/p58 was found to induce significantly the phosphorylation of five other discrete nuclear substrates. Particularly, two nuclear proteins at 75 kDa/pI approximately 6.5 and 85 kDa/pI approximately 5.3, which were not Coomassie Blue stainable, were found to be markedly phosphorylated by CTD kinase. The results of this study call for further study of the role of CTD kinase cdc2/p58 in the phosphorylation of numatrin under physiological conditions and to further characterization of the other nuclear substrates for CTD kinase.
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PMID:Phosphorylation of numatrin and other nuclear proteins by cdc2 containing CTD kinase cdc2/p58. 187 52

The cdc2 gene of the fission yeast Schizosaccharomyces pombe encodes a 34 kDa phosphoprotein with serine/threonine protein kinase activity that acts as the key component in regulation of the eukaryotic cell cycle. We used a repressible promoter fused to the cdc2 cDNA to isolate conditionally dominant negative mutants of cdc2. One of these mutants, DL5, is described in this paper. Overexpression of the mutant protein in a wild-type cdc2 background is lethal and confers cell cycle arrest with a typical cdc- phenotype. Sequencing of the mutant cdc2 gene revealed a single amino acid substitution in a region highly conserved in cdc2-like proteins. The mutant protein exhibits no protein kinase activity, but is able to bind a component(s) required for an active protein kinase complex and thereby prevents binding of this component(s) to the co-existing wild-type cdc2 protein. We also demonstrate that S. pombe p34cdc2 contains no phosphoserine.
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PMID:Expression of a dominant negative allele of cdc2 prevents activation of the endogenous p34cdc2 kinase. 203 6

Fission yeast cell division is initiated by the cdc2/cdc13-cyclin protein kinase which in its catalytically active state comprises the mitotic inducer. During interphase the cdc2/cyclin complex is assembled in an inactive state that requires cdc25+ gene function for M-phase activation. The cdc25+ product, a 76 kd phosphoprotein, is shown to oscillate in abundance during the cell cycle, reaching a peak at G2/M, and to be sensitive to nitrogen starvation. The level of cdc25 is subject to feedback regulation involving both cdc25 and cdc2.
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PMID:Fission yeast cdc25 is a cell-cycle regulated protein. 217 10

In this paper, we review our findings concerning the control of meiosis reinitiation in starfish oocytes and discuss recent advances that lead to characterization of the maturation promoting factor (MPF) responsible for G2-M transition. It is now agreed that appearance of this factor, which triggers nuclear envelope breakdown, chromosome condensation and metaphase spindle formation, corresponds to the activation of a M-phase specific H1-kinase. MPF has been shown to be constituted of equimolar amounts of a 34 kDa catalytic subunit protein homologous to the yeast cdc2/CDC28 gene product and a cyclin protein homologous to the yeast cdc13 gene product. "In vivo" and "in vitro" studies based on the use of inhibitors of protein synthesis, protein kinases, phosphoprotein phosphatases and proteases lead to a better understanding of the complex series of events which regulate activation and inactivation of MPF. In the unfertilized metaphase 2-arrested vertebrate oocyte, it has also been shown that stabilization of MPF depends on the kinase activity of the c-mos protooncogene. This review attempts to illustrate how the significant progress made in the understanding of the regulation of cell cycle transverse directly resulted from the convergence of observations in multidisciplinary studies in yeast genetics, development and oncogenesis. It also offers a model for considering the highly integrated events which, starting at the level of the plasma membrane, may eventually result in early cell differentiation.
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PMID:Meiosis reinitiation as a model system for the study of cell division and cell differentiation. 220 65

The cdc2+ gene function plays a central role in the control of the mitotic cell cycle of the fission yeast Schizosaccharomyces pombe. Recessive temperature-sensitive mutations in the cdc2 gene cause cell cycle arrest when shifted to the restrictive temperature, while a second class of mutations within the cdc2 gene causes a premature advancement into mitosis. Previously the cdc2+ gene has been cloned and has been shown to encode a 34 kDa phosphoprotein with in vitro protein kinase activity. Here we describe the cloning of 11 mutant alleles of the cdc2 gene using two simple methods, one of which is presented here for the first time. We have sequenced these alleles and find a variety of single amino acid substitutions mapping throughout the cdc2 protein. Analysis of these mutations has identified a number of regions within the cdc2 protein that are important for cdc2+ activity and regulation. These include regions which may be involved in the interaction of the cdc2+ gene product with the proteins encoded by the wee1+, cdc13+ and suc1+ genes.
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PMID:Molecular cloning and sequence analysis of mutant alleles of the fission yeast cdc2 protein kinase gene: implications for cdc2+ protein structure and function. 267 50

The cdc2+ gene function has an important role in controlling the commitment of the fission yeast cell to the mitotic cycle and the timing of mitosis. We have raised antibodies against the cdc2+ protein using synthetic peptides and have demonstrated that it is a 34 kd phosphoprotein with protein kinase activity. The protein level and phosphorylation state remain unchanged during the mitotic cycle of rapidly growing cells. When cells cease to proliferate and arrest in G1 the protein becomes dephosphorylated and loses protein kinase activity. Exit from the mitotic cycle and entry into stationary phase may be controlled in part by modulation of the cdc2 protein kinase activity by changes in its phosphorylation state.
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PMID:The cell cycle control gene cdc2+ of fission yeast encodes a protein kinase potentially regulated by phosphorylation. 351 12

ERF (ETS2 Repressor Factor) is a novel member of the ets family of genes, which was isolated by virtue of its interaction with the ets binding site (EBS) within the ETS2 promoter. The 2.7 kb ubiquitously expressed ERF mRNA encodes a 548 amino acid phosphoprotein that exhibits strong transcriptional repressor activity on promoters that contain an EBS. The localization of the DNA-binding domain of the protein at the N-terminus and th repression domain at the C-terminus is reminiscent of the organization of ELK1-like members of the ets family; however, there is no significant homology between ERF and ELK1 or any other ets member outside the DNA-binding domain. The repressor activity of ERF can antagonize the activity of other ets genes that are known transcriptional activators. Furthermore, ERF can suppress the ets-dependent transforming activity of the gag-myb-ets fusion oncogene of ME26 virus. Although ERF protein levels remain constant throughout the cell cycle, the phosphorylation level of the protein is altered as a function of the cell cycle and after mitogenic stimulation. The ERF protein is also hyperphosphorylated in cells transformed by the activated Ha-ras and v-src genes and the transcription repressor activity of ERF is decreased after co-transfection with activated Ha-ras or the kinase domain of the c-Raf-1 gene, indicating that ERF activity is probably regulated by the ras/MAPK pathway. Consistent with the in vivo phosphorylation and inactivation by ras, ERF is efficiently phosphorylated in vitro by Erk2 and cdc2/cyclin B kinases, at sites similar to those detected in vivo. Furthermore, a single mutation at position 526 results in the loss of a specific phosphopeptide both in in vivo and in vitro (by Erk2) labeling. Substitution of Thr526 for glutamic acid also decreases the repression ability of ERF. Our data suggest a model in which modulation of ERF activity is involved in the transcriptional regulation of genes activated during entry into G1 phase. Obstruction of the ERF repressor function by the transactivating members of the ets family of genes (i.e.gag-myb-ets) may be essential for the control of genes involved in cell proliferation and may also underlie their tumorigenic effects.
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PMID:ERF: an ETS domain protein with strong transcriptional repressor activity, can suppress ets-associated tumorigenesis and is regulated by phosphorylation during cell cycle and mitogenic stimulation. 758 8

Using anti-phosphotyrosine immunoaffinity chromatography, we have searched for serine/threonine kinases that are directly regulated by tyrosine phosphorylation in v-src-transformed rat 3Y1 fibroblasts. Tyrosine phosphoprotein preparations from v-src-transformed cells contain a kinase activity that phosphorylates histone H1 in vitro on serine residues and this activity is present at a 20-fold greater level than that in parental cell preparations. This activity elutes from a MonoQ FPLC column as a single peak and gel filtration chromatography suggests that the kinase has a molecular mass of approximately 55 kDa. Tyrosine phosphatase treatment inactivates the histone H1 kinase and this result indicates that the specific activity of the kinase is regulated by tyrosine phosphorylation. Experiments with cells transformed with a temperature-sensitive mutant of the v-src oncogene demonstrate that the tyrosine phosphorylation of the histone H1 kinase is an early event in v-src transformation. The kinase is distinct from known cdc2 family members that contain the PSTAIR motif, because the kinase can be separated almost completely from these proteins by immunoprecipitation with an antibody against p34cdc2. The profile of antibody reactivity and sensitivity to modulators of protein kinases suggests that this activity is distinct from known second messenger-regulated kinases and from previously characterized MAP kinases.
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PMID:Activation of a histone H1 kinase by tyrosine phosphorylation in v-src-transformed fibroblasts. 767 71

We show that the fission yeast dis2 protein phosphatase, which is highly similar to mammalian type 1 phosphatase, is a phosphoprotein containing phosphoserine (phospho-S) and threonine (phospho-T). It has several phosphorylation sites, two of which locate in the C-terminus. Phospho-T was abolished in the alanine substitution mutant at the C-terminal T316, which is conserved as a residue in the cdc2 consensus, TPPR, in a number of type 1-like phosphatases. In G2-arrested cdc2-L7 cells, the degree of T316 phosphorylation was reduced, whereas it was enhanced in metaphase-arrested nuc2-663 mutant cells. Phospho-T was produced in dis2 by fission yeast cdc2 kinase, but not in the substitution mutant A316, indicating that the T316 residue was the site for cdc2 kinase in vitro. Phosphatase activity of wild type dis2 was reduced by incubation with cdc2 kinase, but that of mutant dis2-A316 was not. Phosphorylation of T316 hence has a potential significance in cell cycle control in conjunction with cdc2 kinase activation and inactivation. Overexpression phenotypes of wild type dis2+, sds21+ and mutant dis2-A316, sds21-TPPR genes were consistent with negative regulation of dis2 by phosphorylation. This type of regulation would explain why cells harboring the dis2-11 mutation enter mitosis but fail to exit from it.
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PMID:Phosphorylation of dis2 protein phosphatase at the C-terminal cdc2 consensus and its potential role in cell cycle regulation. 795 97


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