Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CK2”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources
PubMed1999

Molecular surface sequence analysis of several E. coli enzymes and implications for existence of casein kinase-2 bacterial predecessor.

Casein kinase-2 (CK2) is known as pleiotropic eukaryotic protein kinase that phosphorylates significant number of cellular proteins. Not all functions of the protein were registered up to the present time. However, it is known that this Ser/Thr-specific kinase is involved in the cell cycle progression and is essentially required for the eukaryotic cell viability. Fully automated molecular surface analysis procedure for identification of functionally significant surface residues and sequences on the base of protein spatial structure was elaborated. Using the elaborated procedure, several E. coli enzymes spatial structures and sequences were investigated. It was found that most of the casein kinase 2 potential sites found in sequences of enzymes are accessible for modification. Four of the 5 structures studied have CK2 consensus sites that may definitely influence the activity of the enzyme upon phosphorylation. Some of the potential "CK2-sites" has amino acid contents characteristic for physiological substrates of casein kinase 2 in eukaryotes. The main point of the elaborated method and the structural evidence for existence of a putative casein kinase E. coli predecessor or a protein with similar kinase activity are discussed. Physiological, biochemical, structural and evolutionary aspects of the existence of the putative predecessor are considered.

Adenylate Kinase↗
PubMed1999

Mutations in the C-terminal domain of topoisomerase II affect meiotic function and interaction with the casein kinase 2 beta subunit.

Topoisomerase II is a major target of the protein kinase casein kinase 2 (PK CK2) in vivo. All major phosphorylation acceptor sites in the yeast enzyme are found in the C-terminal 350aa. The acceptor sites are generally clustered such that there is more than one modified Ser or Thr within a short peptide. Mutagenesis of the predicted acceptor sites have confirmed that five of the eight predicted sites are targeted in vitro and in vivo by PK CK2. Mutation to nonphosphorylatable, neutral residues provokes at most a 10% increase in mitotic doubling time. Truncation of the enzyme leaves the enzyme catalytically active, but slightly lengthens the doubling time during mitotic growth and impedes progress through meiosis. Since this could reflect the loss of interaction with an important ligand, we have examined whether the C-terminal domain of the yeast enzyme mediates interaction with the regulatory beta subunit of PK CK2, which was previously reported to bind topoisomerase II. We find that point mutation of the phospho-acceptor sites does not abrogate the interaction with a small region of PK CK2beta, while truncation at aa1276 or aa1236 does. The site of interaction within PK CK2beta does not coincide with the highly negatively charged spermine binding site.

Amino Acid Sequence↗
PubMed1999

Diazenes: modificators of tumor cell resistance to cisplatin.

Most studies indicate that modulation of glutathione metabolism may be one of the most promising means of reversing clinical drug resistance. Five new diazene compounds have been synthesized: JK-279, JK-835, JK-913, JK-925 and LV-57 that should, according to their structure and biochemical properties, lower the GSH concentration. In the present study, we examined the influence of diazenes on cisplatin resistance in human cervical (HeLa) and laryngeal carcinoma (HEp2) cells as well as in their cisplatin-resistant sublines (HeLaCA and CK2, respectively). Intracellular GSH content was examined spectrophotometrically by the procedure developed by Tietze. The cell sensitivity to drugs was determined using a modified colorimetric MTT assay. Results show that all examined diazenes lowered GSH concentration. This decrease was insignificant for JK-835 and JK-925 in HeLa and HeLaCA cells, and JK-925 in CK2 cells. In human cervical carcinoma HeLa and HeLaCA cells, JK-279 was mostly active in sensitizing the cells to cisplatin, especially in drug-resistant cells. JK-913, JK-835 and LV-57 reverted partially resistance to cisplatin in HEp2 cells, while none of the diazenes was active in CK2 cells. In conclusion, diazene JK-279 may be useful in the combined treatment (cisplatin + diazene) for the certain type of cancer.

Antineoplastic Agents↗
PubMed2002

Analysis of the carboxypeptidase D cytoplasmic domain: Implications in intracellular trafficking.

Metallocarboxypeptidase D (CPD) is a type 1 transmembrane protein that functions in the processing of proteins that transit the secretory pathway. Previously, CPD was found to be enriched in the trans Golgi network (TGN) and to cycle between this compartment and the cell surface. In the present study, the roles of specific regions of the CPD cytosolic tail in intracellular trafficking were investigated in the AtT-20 cell line. When the CPD transmembrane region and cytosolic tail are attached to the C-terminus of albumin, this protein is retained in the TGN and cycles to the cell surface. Deletion analysis indicates that a C-terminal region functions in TGN-retention; removal of 10 amino acids from the C-terminus greatly increases the amount of fusion protein that enters nascent vesicles, which bud from the Golgi, but does not affect the half-life of the fusion protein or the ability of cell surface protein to return to the TGN. Because the 10-residue deletion disrupts a casein kinase 2 (CK2) consensus site, the two Thr in this site (TDT) were mutated to either Ala (ADA) or Glu (EDE). Neither mutation has an increased rate of budding from the TGN, although the ADA mutant has a shorter half-life than either the wild type sequence or the EDE mutant. Adaptor protein-1 and -2 bind to most of the deletion mutants, the EDE point mutant, and the CK2-phosphorylated CPD tail, but not to the wild type tail. Taken together, these results suggest that CPD localization to the TGN requires both static retention involving the C-terminal domain and phosphorylation at a CK2 site, which regulates the binding of adaptor proteins.

Adaptor Protein Complex alpha Subunits↗
PubMed2005

[Screening ubiquitin/ribosomal protein S27a by yeast two-hybridization system].

BACKGROUND & OBJECTIVE: Protein kinase CK2, a kind of ubiquitous eukaryotic messenger-independent protein serine/threonine kinase, plays a vital role in cell differentiation and proliferation, signal transduction and procession. Activity of CK2 in hematopoietic cells is 2-8 folds higher than that in relevant normal tissues, moreover changes of CK2 activity are correlated to tumor growth. In order to investigate the mechanism of its effect on hematopoietic cells, we used yeast two-hybridization screening the proteins interacting with protein kinase CK2alpha' subunit from HL-60 cells cDNA library. METHODS: The target CK2alpha' cDNA was obtained by amplifying recombinant plasmid pTHCK2A', containing human protein kinase CK2alpha' subunit cDNA, through polymerase chain reaction (PCR). Pst I/Nde I-digested PCR products were directionally cloned into DNA-BD vector pGBKT7, which had also been digested by Pst I/Nde I. The recombinant plasmid was named yeast two-hybridization BD bait plasmid, and confirmed by DNA sequencing, and auto-activated experiments. Total RNA of HL-60 cells was extracted, CLONTECH switching mechanism at 5' end of RNA transcript method was used to construct a cDNA library in yeast cells. Library plasmid was named AD plasmid. BD plasmid and AD plasmid were co-transformed into competent yeast AH109. Yeast two-hybridization was used to screen positive clones. RESULTS: Six proteins, interacting with human protein kinase CK2alpha' subunit, were screened. DNA sequencing and homology comparison showed that one of the proteins was highly homologous with ubiquitin/ribosomal protein S27a (99.8%). CONCLUSION: Using yeast two-hybridization system could screen out ubiquitin/ribosomal protein S27a, which may interact with human protein kinase CK2alpha' subunit, from HL-60 cells.

Base Sequence↗
PubMed2005

Phosphorylation of mdm2 at serine 269 impairs its interaction with the retinoblastoma protein.

We previously reported that protein kinase CK2 phosphorylates the human mdm2 (hdm2) protein at serine residue 269. This phosphorylation site is located in the central acidic, highly-conserved region of mdm2, which is responsible for the interaction with a number of proteins. Studying the influence of phosphorylation of mdm2 by CK2 upon interaction with some of these binding partners, we found that the retinoblastoma (Rb) protein bound more strongly to the unphosphorylated mdm2 than to its CK2-phosphorylated counterpart. An S269 phosphospecific antibody was generated, and reacted with a 60 kDa subpopulation of mdm2 in human cells. We created a mutant mdm2 with a serine to aspartic acid exchange at position 269, which was used to transfect mdm2-/- cells. Cells transfected with the S269D mutant exhibited a different growth behavior than wild-type mdm2-expressing cells, which might be attributed to the altered Rb-mdm2 interaction.

Casein Kinase II↗
PubMed1991

[LDH and CK isoenzyme patterns in the blood plasma of horses with elevated CK, LDH and AST activities].

The distribution of LDH and CK isoenzymes in blood plasma of ten clinically sound Thoroughbreds with reasonable performance and without elevated clinico-chemical blood variables (reference group) was compared with 57 Thoroughbreds, which had histories of mild locomotor disturbances and/or poor performance and had elevated CK, LDH and/or AST activities (trial group). The trial group was subdivided according to the number of altered blood variables and in the groups with two as well as three altered blood variables also according to the extent of alteration of the total CK activity. The pattern of LDH and CK isoenzyme distribution in the blood plasma of the reference group was the following: 22% LDH1, 36% LDH2, 34% LDH3, 6% LDH4 and 2% LDH5 as well as 75% CK1 and 15% CK2. The remaining 10% of the plasma electropherogram could not be alloted to any one of the two CK bands. All trial groups built showed a similar pattern of changes in their isoenzyme distribution independent on kind and combination of altered enzyme activities. The shares of CK1, LDH4 and LDH5 were significantly increased whilst the shares of CK2, LDH1 and LDH2 decreased. A multiple analysis of variance demonstrated that only increased total CK activities had a pronounced effect on distribution of LDH and CK isoenzyme patterns in the trial group (p less than 0.01 for LDH2, LDH3, LDH4, CK1 and p less than 0.05 for CK2). The conclusion of the study was that the altered distribution pattern of LDH and CK isoenzymes of the trial group signalized an increased skeletal muscle membrane leakage.

Animals↗
PubMedDate not supplied

Hyperthermic modulation of resistance to cis-diamminedichloroplatinum (II) in human larynx carcinoma cells.

The aim of the present study was to examine the effect of hyperthermia on cisplatin resistance in two sublines of human larynx carcinoma HEp2 cells. Hyperthermia was tumouricidal for both parental and cisplatin resistant cells, but cisplatin resistant cells were more sensitive to the heat at 43 and 44 degrees C. In combined cisplatin-hyperthermia treatment, heat chemosensitization was observed for parental, as well as for cisplatin resistant cells. At 42 degrees C, and at 43 degrees C, the thermal enhancement ratio (TER) for cisplatin toxicity was higher in resistant than in parental cells. The heating at 42 degrees C decreased the resistance factors in CA3 and CK2 cells from 2.2 and 3.5 to 1.8 and 2.2 respectively. At 43 degrees C, the resistance factors were decreased to 1.7 for CA3 cells and 2.0 for CK2 cells. The heating at 43 degrees C increased intracellular platinum accumulation in all cell lines examined. This effect was more pronounced in resistant, than in parental cells, causing complete reversal of the reduced platinum accumulation found at 37 degrees C in resistant cells. In conclusion, the resistance to cisplatin was partially reversed by hyperthermia in CA3 and CK2 cells. Increased drug accumulation was one of the mechanisms involved in hyperthermic potentiation of cisplatin toxicity and partial reversal of cisplatin resistance in human larynx carcinoma HEp2 cells.

Cell Survival↗
PubMed1997

Protein phosphorylation sites regulate the function of the bipartite NLS of nucleolin.

Nucleolin is a major component of the nucleolus. In Xenopus laevis, a maternal store of nucleolin is accumulated in the multiple nucleoli generated during oogenesis. This maternal nucleolin is distributed throughout the cytoplasm of the egg during oocyte maturation and after fertilization it is gradually reaccumulated in the nuclei of the embryo. Cytoplasmic localization of nucleolin coincides with massive phosphorylation by p34cdc2 kinase, and nuclear translocation is accompanied by net dephosphorylation. Multiple phosphorylation consensus sites for the cell cycle-dependent p34cdc2 kinase and for protein kinase CK2 are clustered in the N-terminal domain of nucleolin. To assess the efficiency of the bipartite nuclear localization signal, we have constructed fusion proteins consisting of maltose binding protein (MBP) and the nuclear localization signal of nucleolin. In addition, either an acidic domain of nucleolin without phosphorylation sites, or an acidic domain containing 4 CK2 sites, or a cluster of 5 cdc2 sites was fused to the MBP-nuclear localization signal (MBP-NLS). Nuclear translocation of these constructs was tested in an in vitro system consisting of Xenopus egg extract and sperm nuclei. Nuclear targetting of MBP by the bipartite nuclear localization signal of nucleolin became significantly more efficient after addition of either CK2 sites or cdc2 sites to the MBP-NLS construct. Yet the cdc2 sites play a dual role. They enhance nuclear translocation exclusively in their dephosphorylated state and promote cytoplasmic localization when phosphorylated, thereby providing a powerful cell cycle-dependent regulatory element of the nuclear localization signal.

Animals↗
PubMed2007

Phosphatase PTEN is inactivated in bovine aortic endothelial cells exposed to cyclic strain.

Hemodynamic forces, including cyclic strain (CS) and shear stress (SS), have been recognized as important modulators of vascular cell morphology and function. PTEN (also known as MMAC1/TEP1) is a lipid phosphatase that leads to a decrease in intracellular phosphatidylinositol 3,4,5 trisphosphate (PIP3) and therefore can modulate the stimulating effect of phosphatidylinositol 3-kinase (PI3K). In this study, we focused on the upstream regulators of the PI3K-Akt pathway by assessing Akt, PTEN, casein kinase 2 (CK2) (a kinase that catalyzes phosphorylation of PTEN), and PI3K activity in endothelial cells (EC) exposed to CS. The activity of phospho-PTEN (n = 4) and phospho-CK2 (n = 4) increased in a time-dependent fashion, reaching maximal activity by 10 min of CS stimulation. The peak of phospho-Akt activity (n = 4) occurred later, at 60 min. Akt activity was altered by transfection of EC with dominant negative PTEN plasmids. Furthermore, CS increased PIP3 immunoreactivity in a time-dependent manner, reaching maximal activity after 60 min of CS stimulation, and these effects were affected by transfection of EC with dominant negative PTEN plasmids. Inhibition of PTEN activity had no effect on CS-mediated cell proliferation but inhibited CS-mediated suppression of apoptosis.

Animals↗
PubMed2000

A method of immobilization on the solid support of complex and simple enzymes retaining their activity.

Immobilization of native proteins, retaining their activity, on the solid support is often crucial for a variety of biochemical assays involving protein-protein interactions. In this study we describe a technique which allows binding of both complex (protein kinase CK2) and simple (calf intestine alkaline phosphatase, CIP) enzymes to the solid support without denaturization of the proteins. This method is based on the covalent cross-linking of the enzymes to the bifunctional resin, containing the secondary amino and thiol groups, in a coupling reaction with the imidoester dimethyl pimelimidate hydrochloride. Both enzymes in their bound form were active in the specific biochemical assays. We also found that the CK2 and CIP resins did not change their activity for at least 3 months, and the quality of these resins were not affected by high salts or reducing agents. Thus, this method can be recommended for general use to generate active enzymes coupled to the solid support.

Animals↗
PubMed1999

Determination of a putative phosphate-containing peptide in calreticulin.

Calreticulin is an abundant endo/sarcoplasmic reticulum (ER/SR) protein that may carry out multiple functions inside cells. Except for calreticulin, all of the major ER/SR Ca2+-binding proteins are substrates for protein kinase CK2 in vitro, which led us to hypothesize that native calreticulin might exist in the phosphorylated form. To investigate this possibility, we purified calreticulin from cardiac microsomes and verified its identity by immunoblot analysis and sequencing of tryptic peptides. Purified calreticulin, like cardiac calsequestrin, contained endogenous phosphate as determined by a Malachite green assay for phosphate. Previous analyses of cardiac calsequestrin have localized phosphate to a single tryptic peptide containing serine phosphate on sites phosphorylated by protein kinase CK2. Using a similar procedure, we analyzed calreticulin tryptic peptides with Malachite green, localizing phosphate binding to a single calreticulin peptide 367LKEEEEDKK. As this peptide contains no phosphorylatable residues, our results suggest that calreticulin may tightly bind phosphate or a phosphate-containing molecule at this site.

Animals↗
PubMed2000

Susceptibility of the prion protein to enzymic phosphorylation.

Ten protein kinases have been assayed for their ability to phosphorylate in vitro the recombinant bovine PrP (25-242) (rbPrP). Substantial phosphorylation was observed with PKC, CK2, and two tyrosine kinases, Lyn and c-Fgr. With regard to CK2, phosphorylation occurs at Ser 154 with a stoichiometry of about 0.1 mol phosphate/mol rbPrP, which is doubled by mild heat treatment of rbPrP. Heat also reduces the overall protein ellipticity, suggesting that reversibly unfolded conformers are more susceptible to phosphorylation. Our data disclose the possibility that phosphorylation might modulate PrP biological activity.

Animals↗
PubMed2001

Possible implication of the Golgi apparatus casein kinase in the phosphorylation of vesicle docking protein p115 Ser-940: a study with peptide substrates.

Phosphorylation of human vescicle docking protein p115 at Ser-942 (homologous to Ser-940 in rat p115) promotes its dissociation from the Golgi membrane. Here we show that a peptide encompassing the 934--950 sequence of p115 is unaffected or poorly phosphorylated by a variety of Ser/Thr protein kinases with the notable exception of the Golgi apparatus casein kinase (G-CK) which phosphorylates it with an efficiency comparable to that of its optimal peptide substrates. In contrast phosphorylation of the p115 peptide by protein kinase CK2 is negligible compared to that of the specific peptide substrates of this kinase. Phosphorylation by G-CK is abolished if a conserved cluster of acidic residues at position between n + 4 and n + 9 (EDDDDE) is replaced by a neutral stretch (GAGAGA). These data strongly support the view that G-CK but not the other two classes of ubiquitous "casein kinases" (CK1 and CK2) is the natural phosphorylating agent of p115.

Amino Acid Sequence↗
PubMed2001

Profiling of protein kinases in the neoplastic transformation of human ovarian surface epithelium.

OBJECTIVE: The aim of this study was to study the pattern of protein kinase expression in a culture model of epithelial ovarian carcinogenesis. METHODS: Cultures of normal human ovarian surface epithelium (OSE), OSE from women with BRCA1 mutations, a cell culture model of preneoplastic (SV40 T-antigen-immortalized, nontumorigenic) and neoplastic (SV40-E-cadherin transfected, tumorigenic) OSE, and three ovarian cancer cell lines were used to represent OSE phenotypes of different genetic backgrounds and at different, progressive stages of neoplastic transformation. The protein kinase network signaling was studied by Western blotting, simultaneously using multiple antibodies for specific protein kinases. RESULTS: High levels of cGMP-dependent protein kinase were found in normal and preneoplastic OSE, but were absent in neoplastic OSE. In contrast, expression of MEK6 was detected exclusively in neoplastic OSE. The expressions of casein kinase II (CK2), p38 mitogen-activated protein kinase (MAPK), cyclin-dependent kinase, and the phosphatidylinositol 3-kinase (PI3K) effectors Akt2 and p70 S6 kinase (S6K) were several-fold higher in neoplastic OSE than in normal OSE, whereas the expressions of the MAPKs extracellular signal-regulated kinases ERK1 and -2 were unchanged. Importantly, constitutive phosphorylation of Akt2 and p70 S6K, as found in neoplastic OSE, was also observed in overtly normal OSE from women with predisposing BRCA1 gene mutations. CONCLUSIONS: These data demonstrate that different repertoires of downstream signaling proteins, particularly those of the MEK6-p38 MAPK-CK2 pathway and the PI3K pathway, are correlated with phenotypic manifestations of a cell culture model of OSE at progressive stages in the development of ovarian cancer. Changes in PI3K effectors are already found in overtly normal OSE from women with BRCA1 mutations.

Animals↗
PubMed2002

Functional analysis of a carboxyl-terminal phosphorylation mutant of the bovine papillomavirus E1 protein.

The papillomavirus E1 protein is essential for viral DNA replication, and phosphorylation of E1 appears to regulate protein function and DNA replication. Serine 584 of bovine papillomavirus E1 is in a conserved motif resembling a CK2 consensus site, and is phosphorylated by CK2 in vitro. Mutation of serine 584 to alanine eliminates replication of the viral genome in transient replication assays. Wild-type and mutant E1 proteins were expressed from recombinant baculoviruses and used to assess biochemical functions of the amino acid 584 substitution. Helicase enzyme activity, E1 binding to the viral E2 protein and to cellular DNA polymerase alpha-primase were all unaffected in the mutant protein. Binding of E1 to viral replication origin DNA sequences was reduced in the mutant, but not eliminated. The carboxyl-terminal region of the protein appears to play a role in regulating E1 function, and adds to a complex picture emerging for papillomavirus DNA replication control.

Amino Acid Substitution↗
PubMed1976

Effects of cadmium on carbonic anhydrase activity and hemoglobin content of rat testes.

The cadmilm-induced (Cd) damage of mammalian testes is thought to be correlated with an inhibition of carbonic anhydrase (CAH) by Cd. Since Cd causes dose-dependent changes in blood flow of the testes, an inhibition of CAH in the testes could be simulated by a decrease of CAH-rich erythrocytes. Therefore, CAH activities and hemoglobin (Hb) content were determined in blood and testes of untreated and Cd-treated Sprague-Dawley rats as well as in testes perfused via the testicular artery. Cd was intraperitoneally applied as CdCl2 in single doses of 1.5, 3.0, and 5.0 mg Cd2+/kg b.w., respectively. 1. The experiments on perfused testes clearly demonstrated that the CAH activities originate from erythrocytes rather than from a tissue located enzyme. 2. The alterations in blood circulation occurring shortly (0.25-1.0 h) after the Cd administration were characterized by a dose-dependent, transient decrease (1.5 mg Cd2+/kg) as well as an increase (3.0 and 5.0 mg Ck2+, respectively) of the Hb content in the testes. 3. Independent of these minor alterations in a later state (14-24 h after 1.5 mg Ck2+/kg, 7-14 h after 3.0 mg Cd2+/kg, and 1-3 after 5.0 mg Cd2+/kg), Cd induced the well known hemorrhagic alterations of the testes with a high increase of Hb content and CAH activity. 4. By means of the correlations between CAH activities and Hb content in blood and testes an inhibition of the CAH by Cd as the primary cause for the tissue damage of the testes could largely be excluded.

Animals↗
PubMed1997

Mitosis-specific phosphorylation of gar2, a fission yeast nucleolar protein structurally related to nucleolin.

The nucleolar protein gar2 of fission yeast is structurally related to the multifunctional nucleolar protein nucleolin from vertebrates and has been shown to be implicated in production of 18S rRNA. gar2 contains several potential casein kinase 2 (CK2) phosphorylation sites and a single putative p34(cdc2 )phosphorylation site in the consensus S50PKK. Here, we show that, like nucleolin, gar2 is phosphorylated in vitro by both highly purified CK2 from CHO cells and p34(cdc2 )from starfish oocytes. Moreover, the substitution of alanine for the N-terminal serine 50 abolishes phosphorylation by p34(cdc2 )in vitro. We also provide evidence that gar2 is phosphorylated in vitro by a p13(suc1)-Sepharose-bound kinase from Schizosaccharomyces pombe extracts that displays cell cycle-regulated activity similar to that of the p34(cdc2(kinase. In vivo 32P labeling of cells indicates that gar2 is a phosphoprotein and that incorporation of phosphate on residue 50 occurs specifically at mitosis. Taken together, these results lead us to propose that gar2 is likely to be an in vivo substrate for the mitotic p34(cdc2 )kinase. However, this posttranslational modification of the gar2 protein does not appear to be essential for normal production of 18S rRNA.

Alanine↗