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)

The addition of recombinant interleukin 2 (rIL-2) to anti-CD3-activated murine G0 phase T cells results in an increased level of tyrosine phosphorylation of a single 97-kDa protein. The degree of tyrosine phosphorylation paralleled the amount of rIL-2 added and correlated with the extent of DNA synthesis. IL-2 treatment resulted in a transient increase in p56lck kinase activity without detectable modification of its level of tyrosine phosphorylation and gel mobility. When G0 T cells were activated by phorbol dibutyrate in the absence of IL-2, the high-affinity IL-2 receptor (IL-2R) expressed failed to induce a proliferative signal, and neither the tyrosine phosphorylation of the 97-kDa protein nor the transient increase in p56lck kinase activity was detected. Northern analysis of the total RNA extracted from these cells showed the accumulation of IL-2R alpha chain-specific mRNA but neither c-myc nor cdc2 mRNA was expressed. The addition of 100 nM rIL-2 to T cells activated by phorbol dibutyrate was able to induce a proliferative response, and under these conditions tyrosine phosphorylation of the 97-kDa protein, the transient increase in p56lck kinase activity, and specific mRNA for IL-2R alpha chain, c-myc, and cdc2 were detected. Unstimulated G0 T cells responded to 100 nM rIL-2 in the same manner as phorbol dibutyrate-activated cells. Irrespective of the signal-transducing structures involved, the IL-2-induced proliferative response closely correlates with an increase in p56lck kinase activity along with the tyrosine phosphorylation of a 97-kDa protein.
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PMID:Murine T-lymphocyte proliferation induced by interleukin 2 correlates with a transient increase in p56lck kinase activity and the tyrosine phosphorylation of a 97-kDa protein. 768 94

Abnormally phosphorylated tau protein is a major component of the cytoskeletal pathology of Alzheimer's disease (AD) found in the neurofibrillary tangle (NFT) and neuritic plaque (NP). Identification of the kinase responsible for this phosphorylation has been difficult. In the test tube, several proline-directed kinases, particularly mitogen-activated protein (MAP) and cdc2 kinase, phosphorylate tau on sites that appear to mimic the abnormally phosphorylated sites in AD. Important unanswered issues include: 1) whether this phosphorylation event occurs in the tightly regulated environment of a living cell; 2) whether this phosphorylation of tau affects its functional properties; and 3) what is the subcellular relationship of proline-directed kinases and tau. We show here that tau can be phosphorylated in cultured hippocampal neurons by the MAP kinase p44mpk, and phosphorylation of tau compromises its functional ability to assemble microtubules. We show further that MAP kinase copurifies with microtubule fractions where it is tyrosine phosphorylated and presumably active. These studies address and raise several important issues regarding the regulation of tau phosphorylation in normal and AD brain.
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PMID:p44mpk MAP kinase induces Alzheimer type alterations in tau function and in primary hippocampal neurons. 768 58

Transformation of cells in culture by polyomavirus is mediated by one of its early gene products, middle-sized tumor antigen (MTAg). This protein forms multiple complexes with cellular enzymes such as tyrosine kinases (pp60c-src), a phosphatidylinositol 3-kinase, and phosphatase 2A. Association with MTAg leads to the activation of pp60c-src through interference with phosphorylation at Tyr-527, a site negatively regulating src kinase activity. MTAg abrogates mitosis-specific activation of pp60c-src, resulting in constitutive high kinase activity of the enzyme throughout all phases of the cell cycle. Here we report that MTAg is transiently modified during mitosis, resulting in an increase in its apparent molecular size on SDS/acrylamide gels. Similarly, MTAg isolated from interphase cells and phosphorylated by the cell cycle-regulated serine/threonine kinase p34cdc2 in vitro has increased molecular mass. The large molecular mass form of the protein can be converted to the authentic 56-kDa form upon dephosphorylation by potato acid phosphatase. Two putative phosphorylation sites for a cdc2-like kinase were identified as Thr-160 and -291, respectively. Conversion of Thr-160 to Ala resulted in a transformation-defective mutant protein that was still capable of associating with pp60c-src, phosphatidylinositol 3-kinase, and phosphatase 2A, while the corresponding mutant in position 291 was wild type with respect to all parameters measured so far. These data suggest that phosphorylation by p34cdc2 or a related cell cycle-regulated kinase modulates the interaction of MTAg with cellular targets that are crucial for cell transformation.
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PMID:Mitosis-specific phosphorylation of polyomavirus middle-sized tumor antigen and its role during cell transformation. 769 Jan 42

Tyrosine phosphorylation status was investigated during mouse mammary tumor development using non-tumorigenic and tumorigenic hyperplastic outgrowth lines. These outgrowth lines were compared with normal mammary glands from pregnant mice and with their corresponding tumors. The levels of total tyrosine phosphorylation in proteins of hyperplastic and neoplastic tissues were 4.7- and 3.4-fold higher than in the normal gland respectively. These results indicate that increases in tyrosine phosphorylation occur in the earliest stages of neoplastic development and are not restricted to neoplastic cells per se. These results led to the identification of the specific proteins showing high levels of tyrosine phosphorylation. Of the eight molecular weight bands of proteins exhibiting detectable levels of tyrosine phosphorylation, the only proteins exhibiting consistently different degrees of phosphorylation between hyperplasias and tumors were of approximately 34 kDa. In a series of six different hyperplasias with tumorigenic potentials ranging from 0 to 93%, the extent of tyrosine phosphorylation of 34 kDa proteins correlated inversely with tumorigenic potential. The levels of p34cdc2 and p33cdk2 proteins were examined, using antibodies specific for the cdc2 and cdk2 proteins. The amounts of p34cdc2 and p33cdk2 proteins were low in non-tumorigenic (TM3 and TM2L) compared to tumorigenic hyperplasias and correlated inversely with tyrosine phosphorylation of 34 kDa proteins during tumor development. Thus in the non-tumorigenic hyperplasias (TM2L and TM3) the majority of p34cdc2 was phosphorylated on tyrosine, in contrast to the p34cdc2 in tumorigenic (TM2H) hyperplasias and tumors. Two-dimensional PAGE analysis of mammary tumor samples with antibodies specific to cdc2, cdk2 and phosphorylated tyrosine revealed one p34cdc2 form, two p33cdk2 isoforms and two phosphotyrosine isoforms of about 33-34 kDa. The results suggest that the high levels of tyrosine phosphorylation in cdc2 and cdk2 reflect the low tumorigenic potential of a subset of mammary preneoplastic hyperplasias. This interpretation is in accord with current concepts on the role of tyrosine phosphorylation in the regulation of the cyclin-dependent kinases.
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PMID:Tyrosine phosphorylation in mouse mammary hyperplasias. 772 75

We have studied changes in cyclin A- and B1-dependent kinases during apoptosis induced in human promyelocytic leukemia (HL60) cells treated with the topoisomerase I inhibitor camptothecin. We found that cyclin B1/Cdc2 kinase activity transiently increases within 30 min after camptothecin treatment. This increase is followed by a rapid inactivation of the cyclin B1/Cdc2 kinase that is associated with Cdc2 tyrosine phosphorylation without any change in Cdc2 or cyclin B1 protein levels. The DNA polymerase inhibitor aphidicolin abrogates camptothecin-induced changes in cyclin B1/Cdc2 kinase activity, indicating that DNA replication-induced DNA damage is essential for both Cdc2 alterations and apoptosis activation. Apoptosis and the initial cyclin B1/Cdc2 kinase activation were amplified using synchronized S-phase cells, and cyclin A/cdk2 kinase did not change under these conditions. The same transient activation and subsequent inactivation of cyclin B1/Cdc2 kinase were observed after DNA damage by etoposide or bis-(2-chloroethyl)methylamine hydrochloride. These observations suggest that DNA damage promotes the transient and unscheduled stimulation of cyclin B1/Cdc2 kinase activity in HL60 cells prior to apoptosis.
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PMID:Unscheduled activation of cyclin B1/Cdc2 kinase in human promyelocytic leukemia cell line HL60 cells undergoing apoptosis induced by DNA damage. 781 49

While testing purines related to the non-specific protein kinase inhibitors N6-dimethylaminopurine and N6-(delta 2-isopentenyl)adenine as potential inhibitors of the p34cdc2/cyclin B kinase, we discovered a compound with high specificity, 2-(2-hydroxyethylamino)-6- benzylamino-9-methylpurine (olomoucine). Kinetic analysis of kinase inhibition reveals that olomoucine behaves as a competitive inhibitor for ATP and as a non-competitive inhibitor for histone H1 (linear inhibition for both substrates). The kinase specificity of this inhibition was investigated for 35 highly purified kinases (including p34cdk4/cyclin D1, p40cdk6/cyclin D3, cAMP-dependent and cGMP-dependent kinases, eight protein kinase C isoforms, calmodulin-dependent kinase II, myosin light-chain kinase, mitogen-activated S6 kinase, casein kinase 2, double-stranded RNA-activated protein kinase, AMP-stimulated kinase, eight tyrosine kinases). Most kinases are not significantly inhibited. Only the cell-cycle regulating p34cdc2/cyclin B, p33cdk2/cyclin A and p33cdk2/cyclin E kinases, the brain p33cdk5/p35 kinase and the ERK1/MAP-kinase (and its starfish homologue p44mpk) are substantially inhibited by olomoucine (IC50 values are 7, 7, 7, 3 and 25 microM, respectively). The cdk4/cyclin D1 and cdk6/cyclin D3 kinases are not significantly sensitive to olomoucine (IC50 values greater than 1 mM and 150 microM, respectively). N6-(delta 2-Isopentenyl)adenine is confirmed as a general kinase inhibitor with IC50 values of 50-100 microM for many kinases. The purine specificity of cyclin-dependent kinase inhibition was investigated: among 81 purine derivatives tested, only C2, N6 and N9-substituted purines exert a strong inhibitory effect on the p34cdc2/cyclin B kinase. An essentially similar sensitivity to this olomoucine family of compounds was observed for the brain-specific cdk5/p35 kinase. Structure/activity relationship studies allow speculation on the interactions of olomoucine and its analogues with the kinase catalytic subunit. Olomoucine inhibits in vitro M-phase-promoting factor activity in metaphase-arrested Xenopus egg extracts, inhibits in vitro DNA synthesis in Xenopus interphase egg extracts and inhibits the licensing factor, an essential replication factor ensuring that DNA is replicated only once in each cell cycle. Olomoucine inhibits the starfish oocyte G2/M transition in vivo. Through its unique selectivity olomoucine provides an anti-mitotic reagent that may preferentially inhibit certain steps of the cell cycle.
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PMID:Inhibition of cyclin-dependent kinases by purine analogues. 792 96

We examined the effect of suramin, an anticancer agent and a functional analog of naturally occuring glycosaminoglycans, on p34cdc2 kinase. We find that suramin strongly inhibits the catalytic activity of purified p34cdc2 kinase (IC50 approximately 4 microM), whereas it only weakly inhibits the p13-agarose precipitated kinase activity from nuclear and cytoplasmic extracts of the asynchronous H69 human small cell lung cancer cells. We also find that the tyrosine phosphorylation of p34cdc2 kinase in the nuclear extract is increased about twice when the extracts are preincubated with 50 microM of suramin prior to the p13-agarose precipitation. We propose that this increase might result from the inhibitory effect of suramin towards p34cdc2-specific tyrosine phosphatases. These results suggest both a direct and an indirect effect of suramin on p34cdc2 kinase. We also find that heparin is a potent inhibitor of purified cdc2 kinase (IC50 approximately 3.5 micrograms/ml). Therefore, glycosaminoglycans might be physiological regulators of p34cdc2 kinase in vivo.
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PMID:Effect of suramin on p34cdc2 kinase in vitro and in extracts from human H69 cells: evidence for a double mechanism of action. 794 7

MPM-2 antigens, a discrete set of phosphoproteins that contain similar phosphoepitopes recognized by the monoclonal antibody MPM-2, are phosphorylated during M-phase induction. Our previous studies suggested that certain MPM-2 antigens are involved in the appearance of maturation-promoting factor (MPF) activity. Because the central mitotic regulator cdc2 kinase has been shown to exhibit MPF activity, we explored the possibility that certain MPM-2 antigens are regulators of cdc2 kinase. We found that MPM-2 binding of its antigens would inhibit the autoamplification of cdc2 kinase in Xenopus oocytes and interfere with cyclin-activation of cdc2 kinase in Xenopus interphase egg extract. Immunodepletion of MPM-2 antigens from cyclin-induced M-phase egg extract caused the inactivation of cdc2 kinase, which was accompanied by an inhibitory phosphorylation of p34cdc2 on Thr 14 and Tyr 15, indicating that at least one MPM-2 antigen is a positive regulator of p34cdc2 dephosphorylation. We then showed that cdc25 from M-phase arrested egg extract is an MPM-2 antigen. These results suggest that phosphorylation of the epitope recognized by MPM-2 may be a crucial event in the activation of cdc25 and that the kinase(s) that phosphorylates this MPM-2 epitope may be an important regulator of cdc2 kinase activation.
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PMID:cdc25 is one of the MPM-2 antigens involved in the activation of maturation-promoting factor. 801

The key regulator of entry into mitosis is the serine/threonine kinase p34cdc2. This kinase is regulated both by association with cyclins and by phosphorylation at several sites. Phosphorylation at Tyr 15 and Thr 14 are believed to inhibit the kinase activity of cdc2. In Schizosaccharomyces pombe, the wee1 (and possibly mik1) protein kinase catalyzes phosphorylation of Tyr 15. It is not clear whether these or other, as yet unidentified, protein kinases phosphorylate Thr 14. In this report we show, using extracts of Xenopus eggs, that the Thr 14-directed kinase is tightly membrane associated. Specifically, we have shown that a purified membrane fraction, in the absence of cytoplasm, can promote phosphorylation of cdc2 on both Thr 14 and Tyr 15. In contrast, the cytoplasm can phosphorylate cdc2 only on Tyr 15, suggesting the existence of at least two distinctly localized subpopulations of cdc2 Tyr 15-directed kinases. The membrane-associated Tyr 15 and Thr 14 kinase activities behaved similarly during salt or detergent extraction and were similarly regulated during the cell cycle and by the checkpoint machinery that delays mitosis while DNA is being replicated. This suggests the possibility that a dual-specificity membrane-associated protein kinase may catalyze phosphorylation of both Tyr 15 and Thr 14.
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PMID:Membrane localization of the kinase which phosphorylates p34cdc2 on threonine 14. 804 20

1H-NMR and 31P-NMR spectroscopy were employed to assess the electrostatic consequences of phosphorylation of single and multiple tyrosine residues in peptides derived from the core and tail autophosphorylation regions of the human insulin receptor tyrosine-kinase domain. In both peptides, phosphorylation was accompanied by changes in the resonances from basic side-chains; those from acidic residues were unaffected. Tyrosine phosphorylation caused increases of up to one in the pKa values of histidine residues situated up to eight residues away in the primary sequence. Titration curve analysis by Hill plots suggested some cooperativity of histidine and phosphate ionizations. Behaviour closely analogous to that of the insulin receptor tail peptide was observed during changes in phosphorylation of the intact insulin receptor kinase domain, suggesting that the electrostatic dissemination effects seen for the isolated peptide are retained by the peptide sequence in the context of the much larger protein. Similar changes in the behaviour of basic residues were also observed upon tyrosine phosphorylation of a cdc2-derived peptide, suggesting that this potential of phosphorylation events to propagate directed structural changes may find a widespread utility in the activation of protein kinases and in the transduction of phosphorylation-based signalling.
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PMID:Phosphorylation effects on flanking charged residues. Structural implications for signal transduction in protein kinases. 807 32


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