Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

Occludin is a protein component of the membrane domain of tight junctions, and has been shown to be phosphorylated in vivo in cultured cells and Xenopus laevis embryos. However, nothing is known about the identity of specific occludin kinase(s) and occludin phosphorylation site(s). Furthermore, nothing is known about the interaction of occludin with cingulin, a cytoplasmic plaque component of tight junctions. Here we report the isolation and sequencing of a complete X. laevis occludin cDNA, and experiments aimed at mapping X. laevis occludin in vitro phosphorylation site(s) and characterizing occludin interaction with cingulin. The sequence of Xenopus occludin is homologous to that of occludins from other species, with identities ranging from 41% to 58%. Bacterially expressed domain E of Xenopus occludin (amino acids 247-493) was a good substrate for protein kinase CK2 (stoichiometry 10.8%, Km 8.4 microM) but not for CK1 kinase, protein kinase A, cdc2 kinase, MAP kinase or syk kinase. Residues Thr375 and Ser379 were identified as potential CK2 phosphorylation sites in this region based on sequence analysis. Mutation of Ser379 to aspartic acid or alanine reduced phosphorylation by CK2 by approximately 50%, and double mutation of Ser379 into aspartic acid and Thr375 into aspartic acid essentially abolished phosphorylation. Glutathione S-transferase (GST) pull-down experiments using extracts of Xenopus A6 epithelial cells showed that constructs of GST fused to wild-type and mutant forms of the C-terminal region of X. laevis occludin associate with several polypeptides, and immunoblot analysis showed that one of these polypeptides is cingulin. GST pull-down experiments using in vitro translated, full-length Xenopus cingulin indicated that cingulin interacts directly with the C-terminal region of occludin.
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PMID:Xenopus laevis occludin. Identification of in vitro phosphorylation sites by protein kinase CK2 and association with cingulin. 1049 Oct 82

Cells require optimum protein synthetic activity in order to support cell proliferation, maintain homeostatic and metabolic integrity, and repair damage. Since growth depends on protein synthesis through ribosome biogenesis, the control of biosynthesis of ribosomes is necessarily a key element for control of growth. Nucleolin is a major nucleolar protein of exponentially growing eukaryotic cells, which is directly involved in the regulation of ribosome biogenesis and maturation. The highly conserved nucleolin contains three major domains through which it controls the organization of nucleolar chromatin, packaging of pre-RNA, rDNA transcription, and ribosome assembly. Numerous reports have implicated the involvement of nucleolin either directly or indirectly in the regulation of cell proliferation and growth, cytokinesis, replication, embryogenesis, and nucleogenesis. Nucleolin, an RNA binding protein, is also an autoantigen, a transcriptional repressor, and a switch region targeting factor. In addition, nucleolin exhibits autodegradation, DNA and RNA helicase activities, and DNA-dependent ATPase activity. An interesting aspect of nucleolin action is that it is a target for regulation by proteolysis, methylation, ADP-ribosylation, and phosphorylation by CKII, cdc2, PKC-xi, cyclic AMP-dependent protein kinase, and ecto-protein kinase. For these and other reasons, nucleolin is fundamental to the survival and proliferation of cells. Considerable progress has been made in recent years with the identification of new nucleolin binding proteins that may mediate these many nucleolin-dependent functions. Nucleolin also functions as a cell surface receptor, where it acts as a shuttling protein between cytoplasm and nucleus, and thus can even provide a mechanism for extracellular regulation of nuclear events. Exploration of the regulation of this multifaceted protein in a remarkable number of diverse functions is challenging.
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PMID:Molecular dissection of nucleolin's role in growth and cell proliferation: new insights. 1054 74

The CDK (cyclin-dependent kinase) family of enzymes is required for the G(1)-to-S-phase and G(2)-to-M-phase transitions during the cell-division cycle of eukaryotes. We have shown previously that the protein kinase CKII catalyses the phosphorylation of Ser-39 in Cdc2 during the G(1) phase of the HeLa cell-division cycle [Russo, Vandenberg, Yu, Bae, Franza and Marshak (1992) J. Biol. Chem. 267, 20317-20325]. To identify a functional role for this phosphorylation, we have studied the homologous enzymes in the budding yeast Saccharomyces cerevisiae. The S. cerevisiae homologue of Cdc2, Cdc28, contains a consensus CKII site (Ser-46), which is homologous with that of human Cdc2. Using in vitro kinase assays, metabolic labelling, peptide mapping and phosphoamino acid analysis, we demonstrate that this site is phosphorylated in Cdc28 in vivo as well in vitro. In addition, S. cerevisiae cells in which Ser-46 has been mutated to alanine show a decrease in both cell volume and protein content of 33%, and this effect is most pronounced in the stationary phase. Because cell size in S. cerevisiae is regulated primarily at the G(1) stage, we suggest that CKII contributes to the regulation of the cell cycle in budding yeast by phosphorylation of Cdc28 as a checkpoint for G(1) progression.
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PMID:Phosphorylation of Cdc28 and regulation of cell size by the protein kinase CKII in Saccharomyces cerevisiae. 1099 56

We review here signalling complexes that we have defined using X-ray analysis in our laboratory. They include growth factors and their receptors: nerve growth factor (NGF) and its hetero-hexameric 7S NGF storage complex, hepatocyte growth factor/scatter factor (HGF/SF) NK1 dimers and fibroblast growth factor (FGF1) in complex with its receptor (FGFR2) ectodomain and heparin. We also review our recent structural studies on intracellular signalling complexes, focusing on phosducin transducin GPry, CK2 protein kinase and its complexes, and the cyclin D-dependent kinase, Cdk6, bound to the cell cycle inhibitor p19INK4d. Comparing the structures of these complexes with others we show that the surface area buried in signalling interactions does not always give a good indication of the strength of the interactions. We show that conformational changes are often important in complexes with intermediate buried surface areas of 1500 to 2000 A2, such as Cdk6INK4 interactions. Some interactions involve recognition of continuous epitopes, where there is no necessity for a tertiary structure and very often the binding conformation is induced during the process of interaction, for example phosducin binding to the betagamma subunits (Gtbetagamma) of the heterotrimeric G protein transducin.
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PMID:Protein-protein interactions in receptor activation and intracellular signalling. 1107 27

DNA helicases catalyse the transient opening of duplex DNA during nucleic acid transactions. Here we report the isolation of a second nuclear DNA helicase (65 kDa) from Pisum sativum (pea) designated pea DNA helicase 65 (PDH65). The enzyme was immunoaffinity purified using an antihuman DNA helicase I (HDH I) antibody column. The purified PDH65 showed ATP- and Mg(2+)-dependent DNA and RNA unwinding activities, as well as ssDNA-dependent ATPase activity. The direction of DNA unwinding was 3' to 5' along the bound strand. Antibodies against HDH I recognized the purified PDH65, and immunodepletion with these antibodies removed the DNA and RNA unwinding and ATPase activities from purified preparations of PDH65. The DNA and RNA unwinding activities were upregulated after phosphorylation of PDH65 with CK2 and cdc2 protein kinases. By incorporation of BrUTP into pea root tissue, followed by double immunofluorescence labelling and confocal microscopy, PDH65 was shown to be localized within the dense fibrillar component of pea root nucleoli in the regions around the rDNA transcription sites. These observations suggest that PDH65 may be involved both in rDNA transcription and in the early stages of pre-rRNA processing.
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PMID:A pea homologue of human DNA helicase I is localized within the dense fibrillar component of the nucleolus and stimulated by phosphorylation with CK2 and cdc2 protein kinases. 1116 78

Cyclin dependent kinases are regulated by phosphorylation and dephosphorylation of the catalytic cdk subunits, by assembly with specific cyclins and by specific inhibitor molecules. Recently, it turned out that cyclins are also phosphoproteins, which means that they are also potential targets for a regulation by phosphorylation and dephosphorylation. Here, we show that cyclin H was phosphorylated by protein kinase CK2. Like most other CK2 substrates cyclin H was much better phosphorylated by the CK2 holoenzyme than by the alpha-subunit alone. By using point mutants derived from the cyclin H sequence we mapped the CK2 phosphorylation site at threonine 315 at the C-terminal end of cyclin H. Phosphorylation at this position had no influence on the assembly of the cyclin H/cdk7/Mat1 complex. However, phosphorylation at amino acid 315 of cyclin H turned out to be critical for a full cyclin H/cdk7/Mat1 kinase activity when the CTD peptide of RNA polymerase II or cdk2 was used as a substrate.
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PMID:The cyclin H/cdk7/Mat1 kinase activity is regulated by CK2 phosphorylation of cyclin H. 1214 Jul 53

The protein kinase CK2 holoenzyme is composed of two regulatory beta- and two catalytic alpha- or alpha(')-subunits. There is ample evidence for the binding of individual subunits of CK2 to various cellular proteins and, moreover, for functions of the individual subunits, which are different from their roles in the holoenzyme. Here, we report that the regulatory cyclin H subunit of the cyclin H/cdk7/Mat1 complex was associated with a protein kinase activity, which shows some similarity with protein kinase CK2. Coimmunoprecipitation experiments supported the existence of complexes of cyclin H and CK2 in mammalian cells. Far Western blot experiments revealed that cyclin H bound to the alpha-subunit but not the alpha(')- and beta-subunits of CK2. Immunofluorescence analysis showed that cyclin H and CK2alpha were colocated in the nucleus. Although cyclin H functions as the regulatory subunit for the cyclin H/cdk7/Mat1 complex, it could not substitute the regulatory beta-subunit of CK2 in its regulatory function of the CK2 activity.
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PMID:Cyclin H is a new binding partner for protein kinase CK2. 1214 20

The immunomodulatory cytokine interleukin-16 (IL-16) represents the secreted C-terminus of a larger precursor, pro-IL-16. Following cleavage by caspase 3, the residual N-terminal domain translocates into the nucleus, inducing G(0)/G(1) cell cycle arrest. We have previously identified a classical bipartite nuclear localization sequence (NLS) in the N-terminal domain of pro-IL-16. We now show that N-terminal to the NLS domain of pro-IL-16 are protein kinase CK2 substrate and cdc2 kinase substrate sites which, along with the NLS, constitute a dual phosphorylation-regulated CcN motif which regulates nuclear localization of pro-IL-16. In addition, we demonstrate that mutation of either site is associated with impairment of the N-terminal domain's ability to induce G(0)/G(1) cell cycle arrest. This is the first description of a functional CcN motif in a cytokine precursor.
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PMID:Prointerleukin-16 contains a functional CcN motif that regulates nuclear localization. 3114 19

p53 is one of the most important regulators of cell proliferation and differentiation and of programmed cell death, triggering growth arrest and/or apoptosis in response to different cellular stress signals. The sequence-specific DNA-binding function of p53 protein can be activated by several different stimuli that modulate the C-terminal domain of this protein. The predominant mechanism of activation of p53 sequence-specific DNA binding is phosphorylation at specific sites. For example, phosphorylation of p53 by PKC (protein kinase C) occurs in undamaged cells, resulting in masking of the epitope recognized by monoclonal antibody PAb421, and presumably promotes steady-state levels of p53 activity in cycling cells. In contrast, phosphorylation by cdk2 (cyclin-dependent kinase 2)/cyclin A and by the protein kinase CK2 are both enhanced in DNA-damaged cells. We determined whether one mechanism to account for this mutually exclusive phosphorylation may be that each phosphorylation event prevents modification by the other kinase. We used non-radioactive electrophoretic mobility shift assays to show that C-terminal phosphorylation of p53 protein by cdk2/cyclin A on Ser315 or by PKC on Ser378 can efficiently stimulate p53 binding to DNA in vitro, as well as binding of the monoclonal antibody Bp53-10, which recognizes residues 371-380 in the C-terminus of p53. Phosphorylation of p53 by CK2 on Ser392 induces its DNA-binding activity to a much lower extent than phosphorylation by cdk2/cyclin A or PKC. In addition, phosphorylation by CK2 strongly inhibits PKC-induced activation of p53 DNA binding, while the activation of p53 by cdk2/cyclin A is not affected by CK2. The presence of CK2-mediated phosphorylation promotes PKC binding to its docking site within the p53 oligomerization domain, but decreases phosphorylation by PKC, suggesting that competition between CK2 and PKC does not rely on the inhibition of PKC-p53 complex formation. These results indicate the crucial role of p53 C-terminal phosphorylation in the regulation of its DNA-binding activity, but also suggest that antagonistic relationships exist between different stress signalling pathways.
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PMID:Activation of the DNA-binding ability of latent p53 protein by protein kinase C is abolished by protein kinase CK2. 1464 Sep 83

Progesterone stimulates G2-arrested Xenopus oocytes to synthesize Mos, a MAPK kinase kinase required for the coordinated activation of cdc2 and the G2/Meiosis I (MI) transition. Mos leads to activation of MAPK, Rsk, and the inhibition of the cdc2 inhibitor Myt1. Previous work identified CK2 beta as a Mos-interacting protein, and suggested that CK2 beta acts as a negative regulator by setting a threshold above which newly made Mos must accumulate to activate MAPK. However, it had not been demonstrated that CK2 beta directly inhibits Mos. We report here that Mos (52-115) is required for CK2 beta binding and can serve as a portable binding domain. To test whether CK2 beta acts at the level of Mos or on a downstream component, we took advantage of previous work that showed injection of Mos arrests rapidly dividing embryonic cells. We find that coinjection of CK2 beta and Mos into embryonic cells inhibits the ability of Mos to arrest cell division. In contrast, CK2 beta does not inhibit the mitotic arrest induced by injection of active Rsk. These results argue that CK2 beta directly binds and inhibits Mos rather than a downstream component, and support that CK2 beta functions as a molecular buffer that prevents premature MAPK activation and oocyte maturation.
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PMID:CK2 beta, which inhibits Mos function, binds to a discrete domain in the N-terminus of Mos. 1506 67


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