39 research outputs found
Dissection of the dual function of the β-subunit of protein kinase CK2 (‘casein kinase-2’): a synthetic peptide reproducing the carboxyl-terminal domain mimicks the positive but not the negative effects of the whole protein
No full textThe dual function of the regulatory beta-subunit of protein kinase CK2 is highlighted by its ability to abolish calmodulin phosphorylation in contrast to its stimulatory effect on the phosphorylation of peptide substrates, Here we show that a synthetic peptide reproducing the C-terminal region of the beta-subunit (beta[170-215]) stimulates to a similar extent the phosphorylation of either the peptide substrate or calmodulin and also protects the catalytic alpha-subunit against thermal inactivation as efficiently as full-length beta-subunit. These data show that the positive and negative functions of the beta-subunit reside in physically separated domains and that the elements responsible for positive regulation are located in the C-terminal region
Protein kinase CK2β regulates peripheral B cell development
No full textSerine-threonine kinase CK2 is involved in oncogenesis of B-cell derived tumors chronic lymphocytic leukemia and multiple myeloma. To gain insights into its role in B-lymphocytes, we generated CK2β conditional knockout mice in B-cells. Non B-cell lineages were normal in CD19-CRE CK2βflox/flox mice. In the bone marrow, CD19-CRE CK2βflox/flox mice displayed a reduction of B-cells and the B220high IgMhigh recirculating population was found dramatically reduced. B-cell progenitors were apparently not affected by CK2β loss. On the contrary, B220+ CD19+ B-cells in peripheral blood, lymph-nodes, spleen and peritoneal cavity were markedly reduced. However, splenic IgDlow IgMhigh B-cell subset was reduced whereas we observed an increase of the IgDhigh IgMlow population, indicating an imbalance between the frequency of follicular (FO) and marginal zone (MZ) B-cells. Detailed FO and MZ B-cell populations analysis showed that FO B-cells were reduced by approximately 35-40% (from 72% to 45%), whereas MZ B-cells were increased up to three folds (from 8.5% to 23%). Histological analysis of CD19-CRE CK2βflox/flox spleens revealed a reduction of the size of follicles, absence of spontaneous germinal centers and an expansion of the interfollicular-marginal zone areas. In vitro class switch recombination assays demonstrated a moderate impairment in IgG1 and IgG3 class switch. In vitro cell cycle analysis experiments suggested an impairment in G1-S and S-G2 transition of CD19-CRE CK2βflox/flox B cells. Results of in vivo experiments testing T-cell dependent and T-cell independent responses will be described.
Our study places CK2β as a novel regulator of B-lymphocyte development and survival
A-Raf kinase is a new interacting partner of protein kinase CK2 β subunit
No full textAbstractIn a search for protein kinase CK2 β subunit binding proteins using the two-hybrid system, more than 1000 positive clones were isolated. Beside clones for the α′ and β subunit of CK2, there were clones coding for a so far unknown protein, whose partial cDNA sequence was already deposited in the EMBL database under the accession numbers R08806 and Z17360, for the ribosomal protein L5 and for A-Raf kinase. All isolated clones except the one for CK2 β showed no interaction with the catalytic α subunit of CK2. A-Raf kinase is a new interesting partner of CK2 β. The isolated A-Raf clone represented amino acids 268–606, but also a full length A-Raf clone interacted with CK2 β. At the site of CK2 β, residue 175 and amino acids between residues 194 and 200 are likely to be involved in direct interaction.© 1997 Federation of European Biochemical Societies
Extraribosomal function of the acidic ribosomal P1-protein YP1α from Saccharomyces cerevisiae
No full textThe yeast acidic ribosomal P-proteins YP1α, YP1β, YP2a and YP2b were studied for a possible transactivation potential beside their ribosomal function. The fusions of P-proteins with the GAL4 DNA-binding domain were assayed toward their transcriptional activity with the aid of reporter genes in yeast. Two of the P-proteins, YP1α and YP1β, exhibited transactivation potential, however, only YP1α can be regarded as a potent transactivator. This protein was able to transactivate a reporter gene associated with two distinct promoter systems, GAL1 or CYC1. Additionally, truncated proteins of YP1α and YP1β were analyzed. The N-terminal part of YP1α fused to GAL4-BD showed transactivation potential but the C-terminal part did not. Our results suggest a putative extraribosomal function for these ribosomal proteins which consequently may be classified as "moonlighting" proteins
Aldosterone rapidly activates Src kinase in M-1 cells involving the mineralocorticoid receptor and HSP84
No full textAbstractWe investigated the effect of aldosterone on Src kinase. In the kidney cell line, M-1 aldosterone leads to a >2-fold transient activation of Src kinase seen as early as 2 min after aldosterone administration. Maximal Src kinase activation was measured at an aldosterone concentration of 1 nM. In parallel to activation, autophosphorylation at Tyr-416 of Src kinase increased. Src kinase activation was blocked by spironolactone. Aldosterone led to increased association of Src with HSP84. Furthermore, rapamycin blocked aldosterone-induced Src activation. We conclude that Src activation by aldosterone is mediated through the mineralocorticoid receptor and HSP84
An Exploratory Long-Term Open Source Activity Analysis: Implications from Empirical Findings on Activity Statistics
No full textInternational audienceOpen source software (OSS) activities are diverse and difficult to capture. The author attempts a web service-based observation of OSS activities. Small community factor is discussed from a social viewpoint
Structure of protein kinase CK2: Dimerization of the human β-subunit
No full textAbstractProtein kinase CK2 has been shown to be elevated in all so far investigated solid tumors and its catalytic subunit has been shown to serve as an oncogene product. CK2 is a hetero-tetrameric serine-threonine kinase composed of two catalytic (α and/or α′) and two regulatory β-subunits. Using the two-hybrid system we could show that the α- or α′-subunits of CK2 can interact with the β-subunits of CK2, but not with other α- or α′-subunits. By comparison, the β-subunit of CK2 can interact with another β-subunit. Important amino acids for successful dimerization of the β-subunit were localized between amino acid residues 156 and 165. Furthermore, we identified residues between amino acid 170 and 180 which antagonize the dimerization
Abstract 4541: Highly sensitive kinase assays combining Carna Biosciences QSS Assist ELISA reagents with the Meso Scale Discovery MULTI-ARRAY platform.
No full textCrystal structure of a C-terminal deletion mutant of human protein kinase CK2 catalytic subunit
No full textUdgivelsesdato: 2003-Jul-25Protein kinase CK2 (formerly called: casein kinase 2) is a heterotetrameric enzyme composed of two separate catalytic chains (CK2alpha) and a stable dimer of two non-catalytic subunits (CK2beta). CK2alpha is a highly conserved member of the superfamily of eukaryotic protein kinases. The crystal structure of a C-terminal deletion mutant of human CK2alpha was solved and refined to 2.5A resolution. In the crystal the CK2alpha mutant exists as a monomer in agreement with the organization of the subunits in the CK2 holoenzyme. The refined structure shows the helix alphaC and the activation segment, two main regions of conformational plasticity and regulatory importance in eukaryotic protein kinases, in active conformations stabilized by extensive contacts to the N-terminal segment. This arrangement is in accordance with the constitutive activity of the enzyme. By structural superimposition of human CK2alpha in isolated form and embedded in the human CK2 holoenzyme the loop connecting the strands beta4 and beta5 and the ATP-binding loop were identified as elements of structural variability. This structural comparison suggests that the ATP-binding loop may be the key region by which the non-catalytic CK2beta dimer modulates the activity of CK2alpha. The beta4/beta5 loop was found in a closed conformation in contrast to the open conformation observed for the CK2alpha subunits of the CK2 holoenzyme. CK2alpha monomers with this closed beta4/beta5 loop conformation are unable to bind CK2beta dimers in the common way for sterical reasons, suggesting a mechanism to protect CK2alpha from integration into CK2 holoenzyme complexes. This observation is consistent with the growing evidence that CK2alpha monomers and CK2beta dimers can exist in vivo independently from the CK2 holoenzyme and may possess physiological roles of their own
Protein kinase CK2: evidence for a protein kinase CK2β subunit fraction, devoid of the catalytic CK2α subunit, in mouse brain and testicles
No full textAbstractThe highest CK2 activity was found in mouse testicles and brain, followed by spleen, liver, lung, kidney and heart. The activity values were directly correlated with the protein expression level of the CK2 subunits α (catalytic) and β (regulatory). The α′ subunit was only detected in brain and testicles. By contrast, Northern blot analyses of the CK2α mRNA revealed a somewhat different picture. Here, the strongest signals were obtained for brain, liver, heart and lung. In kidney, spleen and testicles mRNAs were only weakly detectable. For CK2α′ mRNA distribution strong signals were observed for lung, liver and testicles. In the case of CK2β mRNA the highest signals were found for testicles, kidney, brain and liver. The amount of CK2β mRNA in testicles was estimated to be about 6-fold higher than in brain. The strongest CK2β signals in the Western blot were found for testicles and brain. The amount of CK2β protein in brain in comparison to the other organs (except testicles) was estimated to be ca. 2–3-fold higher whereas the ratio of CK2β between testicles and brain was estimated to be 3–4-fold. Results from the immunoprecipitation experiments support the notion for the existence of free CK2β population and/or CK2β in complex with other protein(s) present in brain and testicles. In all other mouse organs investigated, i.e. heart, lung, liver, kidney and spleen, no comparable amount of free CK2β was observed. This is the first physiological evidence for the existence of a ‘free CK2β’ (or in complex with proteins other than CK2α) in normal animal tissue apart from the hitherto dogmatic association with CK2α in a tetrameric holoenzyme complex
