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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein kinase CKII is composed of two catalytic (alpha or alpha') subunits and two regulatory (beta) subunits. The CKIIbeta subunit is thought to mediate the tetramer formation and interact with other target proteins. Previously we have shown that CKIIbeta interacts with ribosomal proteins L5 and L41, DNA topoisomerase IIbeta, and SAG/CKBBP1. In this study, the two-hybrid system was used to define the subregions of CKIIbeta that are involved in the interaction with L5, L41, topoisomerase IIbeta, SAG/CKBBP1, and unknown proteins, CKBBP2 and CKBBP3. The results indicated that the region between residues 1 and 167 of CKIIbeta is common binding site for L5, topoisomerase IIbeta, SAG/CKBBP1, and L41. The region between amino acids 19 and 167 of CKIIbeta is sufficient for the interaction with CKBBP3. The region between residues 67 and 130 of CKIIbeta is a minimal fragment that is required for interaction with CKBBP2. Overlay experiments showed that the region between residues 1 and 167 of CKIIbeta interacts with L5, L41, and SAG/CKBBP1 in vitro. These results suggest that the binding sites of CKIIbeta for these target proteins are not located within a small linear sequence stretch, but rather are created by a three-dimensional structure.
Mol Cells 2001 Oct 31
PMID:Mapping of the interaction domain of the protein kinase CKII beta subunit with target proteins. 1171 May 15

Salinity is an important limiting factor in plant growth and development. We have cloned a catalytic subunit of the sugar beet protein kinase CK2 (BvCKA2) by functional expression in yeast of a NaCl-induced cDNA library. BvCKA2 was able to increase the yeast tolerance to NaCl and to functionally complement the cka1 cka2 yeast double mutant upon over-expression. Southern blot analysis indicated that, in sugar beet, the BCKA2 gene is a member of a multigene family. The mRNA levels of BvCKA2 were up-regulated in response to NaCl stress which suggests that protein kinase CK2 may be involved in the plant response to salt stress.
Plant Mol Biol 2001 Nov
PMID:A catalytic subunit of the sugar beet protein kinase CK2 is induced by salt stress and increases NaCl tolerance in Saccharomyces cerevisiae. 1172 43

We have demonstrated previously that Nopp44/46, an abundant nucleolar phosphoprotein of Trypanosoma brucei, is associated with a protein kinase. In many organisms multiple nucleolar proteins are phosphorylated by the protein kinase CK2, formerly known as casein kinase II. Here we report the identification of two T. brucei genes, CK2a1and CK2a2, which encode protein kinases bearing signature motifs common to CK2 catalytic subunits. The protein specified by CK2a1, designated CK2alpha, was capable of associating with Nopp44/46 as assessed by yeast two-hybrid analysis. An epitope-tagged version of CK2alpha expressed in T. brucei colocalized with Nopp44/46, with a largely nucleolar localization. This localization contrasts with the predominantly nuclear localization of mammalian CK2. When expressed in Escherichia coli, TbCK2alpha was catalytically active and phosphorylated Nopp44/46. Together these data demonstrate that TbCK2alpha is a Nopp44/46-associated kinase. Competition assays revealed that, unlike most CK2s, TbCK2alpha discriminates highly between ATP and GTP. This distinction may be associated with the substitution of glutamic acid and alanine for the di-asparagine motif thought to participate in purine interaction.
Mol Biochem Parasitol 2002 Jan
PMID:Molecular cloning of Trypanosoma brucei CK2 catalytic subunits: the alpha isoform is nucleolar and phosphorylates the nucleolar protein Nopp44/46. 1175 90

Transcriptional corepressors of the Groucho/transducin-like Enhancer of split (Gro/TLE) family regulate a number of developmental pathways in both invertebrates and vertebrates. They form transcription repression complexes with members of several DNA-binding protein families and participate in the regulation of the expression of numerous genes. Despite their pleiotropic roles, little is known about the mechanisms that regulate the functions of Gro/TLE proteins. It is shown here that Gro/TLEs become hyperphosphorylated in response to neural cell differentiation and interaction with the DNA-binding cofactor Hairy/Enhancer of split 1 (Hes1). Hyperphosphorylation of Gro/TLEs is correlated with a tight association with the nuclear compartment through interaction with chromatin, suggesting that hyperphosphorylated Gro/TLEs may mediate transcriptional repression via chromatin remodeling mechanisms. Pharmacological inhibition of protein kinase CK2 reduces the Hes1-induced hyperphosphorylation of Gro/TLEs and causes a decrease in the chromatin association of the latter. Moreover, the transcription repression activity of Gro/TLEs is reduced by protein kinase CK2 inhibition. Consistent with these observations, Gro/TLEs are phosphorylated in vitro by purified protein kinase CK2. Taken together, these results implicate protein kinase CK2 in Gro/TLE functions. They suggest further that this kinase is involved in a hyperphosphorylation mechanism activated by Hes1 that promotes the transcription repression functions of Hes1-Gro/TLE protein complexes.
Mol Cell Biol 2002 Jan
PMID:Role for Hes1-induced phosphorylation in Groucho-mediated transcriptional repression. 1175 36

The dramatic segregation of the nucleolar components in winter-acclimatized carp is the most striking cellular-phenotypical feature observed during the seasonal adaptation of this fish toward the circannual changes in its habitat. Our studies also show that the carp habitat temperature and photoperiod winter conditions provoke a remarkable reduction of both rRNA transcription and the processing of their precursors. To gain knowledge on the mechanisms involved in the regulation of nucleolar activity during the seasonal adaptation process, we studied the behavior of some genes, specifically snoRNA U3 and protein kinase CK2. Consistent with the reduction in the synthesis and processing of pre-rRNA observed during the cold season, the level of CK2beta expression decreases in winter when compared to that attained in summer. Similarly, in winter, liver and kidney cells contain lower levels of CK2beta subunit protein compared to summer. CK2 is associated with or modifies different factors and enzymes involved in the nucleolar activity; therefore, its higher or lower content could be part of the molecular mechanisms underlying the nucleolar seasonal changes that occur during the compensatory acclimatization process.
Mol Cell Biochem 2001 Nov
PMID:Environmental reprogramming of the expression of protein kinase CK2beta subunit in fish. 1182 60

We have recently reported that protein kinase CK2 phosphorylates both in vivo and in vitro residue serine-46 of the cell cycle regulating protein Cdc28 of budding yeast Saccharomyces cerevisiae, confirming a previous observation that the same site is phosphorylated in Cdc2/Cdk1, the human homolog of Cdc28. In addition, S. cerevisiae in which serine-46 of Cdc28 has been mutated to alanine show a decrease of 33% in both cell volume and protein content, providing the genetic evidence that CK2 is involved in the regulation of budding yeast cell division cycle, and suggesting that this regulation may be brought about in G1 phase of the mammalian cell cycle. Here, we extended this observation reporting that the mutation of serine-46 of Cdc28 to glutamic acid doubles, at least in vitro, the H1-kinase activity of the Cdc28/cyclin A complex. Since this mutation has only little effects on the cell size of the cells, we hypothesize multiple roles of yeast CK2 in regulating the G1 transition in budding yeast.
Mol Cell Biochem 2001 Nov
PMID:Mutation at the CK2 phosphorylation site on Cdc28 affects kinase activity and cell size in Saccharomyces cerevisiae. 1182 61

In plants, protein kinase CK2 is involved in different processes that control many aspects of metabolism and development. In mammals and yeast the enzyme is a heterotetramer composed of two types of subunits. During years the subunit composition of the maize protein kinase CK2 enzyme has been a source of controversy. We have recently characterized the maize holoenzyme subunits. Our results show that multiple catalytic and regulatory subunits are expressed in maize and are able to specifically interact with other alpha and beta subunits suggesting a high level of heterogeneity in the typical heterotetrameric structure. Here, we summarize data available on plant CK2 enzymes, in order to clarify the distinctive features and functions of plant protein kinase CK2.
Mol Cell Biochem 2001 Nov
PMID:Distinctive features of plant protein kinase CK2. 1182 62

To shed light on the structural features underlying high constitutive activity of protein kinase CK2 a number of mutants of the human CK2alpha-subunit altered in the interactions between the N-terminal segment and the activation loop have been generated and shown to be defective in catalytic activity. In particular the truncated mutant delta2-12 displays under standard conditions an almost complete loss of catalytic activity accounted for by a dramatic rise in its Km forATP (from 10 to 206 microM) and a reduced Kcat. Such a drop in efficiency is paralleled by conformational disorganization, as judged from Superdex 75 gel filtration profile. Both catalytic properties and gel filtration behaviour similar to those of wild type CK2alpha were restored upon association with the regulatory beta-subunit, suggesting that constitutive activity is conferred to CK2alpha and to CK2 holoenzyme through different molecular mechanisms. In the holoenzyme an assumable release of tension at the backbone of Ala-193 (as seems to be indicated by a comparison of the crystal structures of maize CK2alpha alone vs. a CK2alpha-beta peptide complex) may result in the ability of the activation loop to adopt its proper conformation independently of interactions with the N-terminal segment.
Mol Cell Biochem 2001 Nov
PMID:Generation of mutants of CK2alpha which are dependent on the beta-subunit for catalytic activity. 1182 64

We have previously reported the participation of the protein kinase CK2 in the mechanism by which salicylic acid activates transcription of genes, such as those coding for glutathion S-transferases, in tobacco. With the purpose of further studying the participation of CK2 in this signal transduction pathway, we isolated and sequenced the cDNA from the NtCK2A gene, coding for the catalytic alpha subunit of CK2 from tobacco. The NtCK2A cDNA was isolated by screening of a tobacco cDNA library with a heterologous probe from Arabidopsis thaliana, followed by 3' RACE to obtain the 3' region. Sequence analysis of the NtCK2A cDNA showed a high level of identity between this CK2alpha protein sequence and the corresponding sequences of other plant species such as Arabidopsis and maize (92-95% identity), or those of animal species such as human and Xenopus laevis (75% identity). The expression of the NtCK2A gene in different tissues from tobacco plants was analyzed by Northern blot. High levels of expression of this gene were observed in proliferating tissues such as shoot and root apical meristems. A recombinant CK2alpha protein was obtained after expression of the NtCK2A cDNA in Escherichia coli. The ability of this recombinant CK2alpha subunit to phosphorylate casein was inhibited by heparin and stimulated by the CK2beta subunit from Xenopus laevis.
Mol Cell Biochem 2001 Nov
PMID:Cloning and characterization of the cDNA coding for the catalytic alpha subunit of CK2 from tobacco. 1182 63

The phosphorylation of HIV-1 Rev by protein kinase CK2 is strictly dependent on the regulatory beta subunit of the kinase and is deeply affected by conformational changes of the substrate outside the phosphorylation site. Here we show that Rev modulates a variety of CK2 properties, including autophosphorylation, catalytic activity toward calmodulin, and susceptibility to polycationic effectors, whose common denominator is the involvement of the beta subunit. Rev's two major CK2 sites are located at its N-terminus, immediately adjacent to a helix-loop-helix motif. By comparing the behaviour of full-size Rev with that of synthetic peptides reproducing, with suitable modifications, its N-terminal 26 amino acids including the phosphoacceptor site (Ser 5, Ser 8) and amphipathic helix-1, it appears that the functional interaction of the N-terminal portion of Rev with the N-terminal domain of the beta subunit must rely on both electrostatic and hydrophobic interactions. The former mainly involve Rev's arginine-rich domain (residues 35-50) in helix-2, while the latter are mostly mediated by residues 12-24 of helix-1. These data disclose the possibility that, besides displaying protective, regulatory and targeting properties with respect to the catalytic subunit, the CK2 beta subunit also plays a role as a docking site for a subset of CK2 substrates.
Mol Cell Biochem 2001 Nov
PMID:HIV-1 Rev transactivator: a beta-subunit directed substrate and effector of protein kinase CK2. 1182 66


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