Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A peptide derived from p34cdc2, cdc2(6-20)NH2 with the amino acid sequence of KVEKIGEGTYGVVYK-amide, was found to be a specific and efficient substrate for a pp60c-src-related protein tyrosine kinase from bovine spleen (STK). Glu-12 and Thr-14 were identified to be substrate specificity determinants in this peptide (Cheng, H.-C., Litwin, C. M. E., Hwang, D. M., and Wang, J. H. (1991) J. Biol. Chem. 266, 17919-17925). In this study, we demonstrated the presence of cdc2(6-20)NH2 peptide tyrosine kinase activity in the membrane fractions of bovine brain, spleen, thymus, lung, liver, and kidney. Hydroxylapatite column chromatography of thymus membrane extract revealed four protein tyrosine kinases, TK-I, TK-II, TK-III, and TK-IV, with different relative activities toward cdc2(6-20)NH2 and a general tyrosine kinase substrate, poly(Glu/Tyr). Only TK-I and TK-II showed significant activity toward cdc2(6-20)NH2, they were suggested as belonging to the src-family by virtue of their cross-reactivity with an antibody against a synthetic peptide corresponding to a conserved sequence of src-family kinases. Further immunological characterization using antibodies specific to individual src-related protein tyrosine kinases suggested that TK-I, TK-II, and STK are bovine homologs of p56lck, p55fyn, and p56lyn, respectively. Substrate specificity and kinetic characterization of src-family tyrosine kinases including human platelet pp60c-src, bovine p56lyn, p56lck, and p55fyn, as well as several non-src-related tyrosine kinases including epidermal growth factor receptor, p43v-abl, TK-III, and TK-IV showed that all the src-family tyrosine kinases but none of the other kinases displayed efficient cdc2(6-20)NH2 phosphorylation. In all cases, the high efficiency of cdc2(6-20)NH2 peptide phosphorylation could be markedly attenuated when Glu-12 and Thr-14 of the peptide were substituted, respectively, by valine and serine.
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PMID:A synthetic peptide derived from p34cdc2 is a specific and efficient substrate of src-family tyrosine kinases. 157 58

A protein tyrosine kinase has been purified from the particulate fraction of bovine spleen to a specific activity of 0.217 mumol/min/mg at 100 microM ATP and 3 mM [Val5] angiotensin II. Both the angiotensin phosphorylation activity and immunoreactivity towards an antibody preparation raised against a synthetic peptide containing the autophosphorylation site of pp60c-src, Cys-src(403-421), were monitored during the purification. The purified sample displayed three closely spaced protein bands with molecular weights of 50-55 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All bands could be phosphorylated exclusively on tyrosine residues under autophosphorylation conditions. All reacted on immunoblots with an antibody raised against a synthetic peptide corresponding to the consensus autophosphorylation site of members of the pp60c-src family of tyrosine kinases. Tryptic phosphopeptide maps of the three proteins were essentially indistinguishable. The results suggest that the purified enzyme preparation contained mainly three closely related pp60c-src-family protein tyrosine kinases or a pp60src-family protein tyrosine kinase modified posttranslationally to give three closely spaced protein bands on sodium dodecyl sulfate gel. Neither of these proteins appears to be pp60c-src or p56lck. The spleen protein tyrosine kinase was found to phosphorylate a p34cdc2 kinase peptide, Cys-cdc2(8-20), which contained the regulatory tyrosine residue Tyr-15 about 20 times better than [Val5]angiotensin II or Cys-src(403-421) peptide at a peptide substrate concentration of 1 mM. In contrast, epidermal growth factor receptor kinase partially purified from A431 cells did not show preference for Cys-cdc2(8-20) as its substrate. Although Cys-cdc2(8-20) contained two tyrosine residues, only the tyrosine corresponding to Tyr-15 in p34cdc2 was phosphorylated by the spleen tyrosine kinase. The observation suggests that the primary structure surrounding Tyr-15 of p34cdc2 contains substrate structural determinants specific for the spleen tyrosine kinase.
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PMID:Purification and characterization of a pp60c-src-related tyrosine kinase that effectively phosphorylates a synthetic peptide derived from p34cdc2. 170 31

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

Activation of the multicomponent interleukin-2 receptor (IL-2R) complex leads to a rapid increase in tyrosine phosphorylation of a number of cellular proteins including the IL-2R beta and IL-2R gamma chains of the IL-2R and the RAF-1 serine threonine kinase. In addition, phosphatidylinositol 3-kinase (PI-3K) protein and activity can be immunoprecipitated with anti-phosphotyrosine and anti-IL-2R beta antibodies from IL-2-activated but not resting T lymphocytes. We have demonstrated that the SH2 (SRC homology 2) domains of the 85 kDa subunit of PI-3K are sufficient to mediate binding of the PI-3K complex to tyrosine phosphorylated, but not non-phosphorylated IL-2R beta, suggesting that tyrosine phosphorylation is an integral component of the activation of PI-3K by the IL-2R. Since none of the members of the IL-2R complex contains an intrinsic tyrosine kinase domain, IL-2-induced tyrosine phosphorylation must be the consequence of activation of intracellular tyrosine kinases. SRC family members including lck, lyn and fyn have been demonstrated to associate with IL-2R beta through binding of the kinase domain to the acidic domain of IL-2R beta. However, we have demonstrated that the serine rich (SD) region of the cytosolic domain of IL-2R beta is also required for association of a tyrosine kinase with the IL-2R complex and that IL-2 can induce proliferation and tyrosine phosphorylation in cell lines which lack the known SRC family kinases expressed by T lymphocytes. Thus members of other kinase families besides SRC may also be involved in mediating IL-2 signal transduction. Biochemical studies and studies of cells expressing mutant IL-2 receptors indicate that IL-2-induced tyrosine kinase activation initiates a complex signaling cascade. The cascade includes SRC family kinase members such as lck, fyn, and lyn, activation of Raf-1 and PI-3K, and ras, and increased expression of the fos, fra-1, and jun protooncogenes. In addition, ligation of the IL-2R leads to rapid increases in myc expression and more delayed increases in the expression of the cdc2 and cdk2 kinases and the cyclins through a tyrosine phosphorylation independent pathway. Whether other biochemical processes initiated by IL-2R ligation, including activation of the MAP2, p70S6 and p90RSK serine threonine kinases, activation of NF-kappa B, and increased expression of Raf-1, Pim-1, bcl-2, IL-2R alpha and IL-2R beta, are consequences of the IL-2-induced tyrosine kinase cascade remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Transmembrane signaling by the interleukin-2 receptor: progress and conundrums. 826 Jun 51

To determine if nitration of tyrosine residues by peroxynitrite (PN), which can be generated endogenously, can disrupt the phosphorylation of tyrosine residues in proteins involved in cell signaling networks, we studied the effect of PN-promoted nitration of tyrosine residues in a pentadecameric peptide, cdc2(6-20)NH2, on the ability of the peptide to be phosphorylated. cdc2(6-20)NH2 corresponds to the tyrosine phosphorylation site of p34cdc2 kinase, which is phosphorylated by lck kinase (lymphocyte-specific tyrosine kinase, p56lck). PN nitrates both Tyr-15 and Tyr-19 of the peptide in phosphate buffer (pH 7.5) at 37 degrees C. Nitration of Tyr-15. which is the phosphorylated amino acid residue, inhibits completely the phosphorylation of the peptide. The nitration reaction is enhanced by either Fe(III)EDTA or Cu(II)-Zn(II)-superoxide dismutase (Cu,Zn-SOD). The kinetic data are consistent with the view that reactions of Fe(111)EDTA or Cu,Zn-SOD with the cis form of PN yield complexes in which PN decomposes more slowly to form N02+, the nitrating agent. Thus, the nitration efficiency of PN is enhanced. These results are discussed from the point of view that PN-promoted nitration will result in permanent impairment of cyclic cascades that control signal transduction processes and regulate cell cycles.
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PMID:Peroxynitrite disables the tyrosine phosphorylation regulatory mechanism: Lymphocyte-specific tyrosine kinase fails to phosphorylate nitrated cdc2(6-20)NH2 peptide. 862 43

Tolerance in vivo and its in vitro counterpart, anergy, are defined as the state in which helper T lymphocytes are alive but incapable of producing IL-2 and expanding in response to optimal antigenic stimulation. Anergy is induced when the T cell receptor (TCR) is engaged by antigen in the absence of costimulation or IL-2. This leads to unique intracellular signaling events that stand in contrast to those triggered by coligation of the TCR and costimulatory receptors. Specifically, anergy is characterized by lack of activation of lck, ZAP 70, Ras, ERK, JNK, AP-1, and NF-AT. In contrast, anergizing stimuli appear to activate the protein tyrosine kinase fyn, increase intracellular calcium levels, and activate Rap1. Moreover, anergizing TCR signals result in increased intracellular concentrations of the second messenger cAMP. This second messenger upregulates the cyclin-dependent kinase (cdk) inhibitor p27kip1, sequestering cyclin D2-cdk4, and cyclin E/cdk2 complexes and preventing progression of T cells through the G1 restriction point of the cell cycle. In contrast, costimulation through CD28 prevents p27kip1 accumulation by decreasing the levels of intracellular cAMP and promotes p27kip1 down-regulation due to direct degradation of the protein via the ubiquitin-proteasome pathway. Subsequent autocrine action of IL-2 leads to further degradation of p27kip1 and entry into S phase. Understanding the biochemical and molecular basis of T cell anergy will allow the development of new assays to evaluate the immune status of patients in a variety of clinical settings in which tolerance has an important role, including cancer, autoimmune diseases, and organ transplantation. Precise understanding of these biochemical and molecular events is necessary in order to develop novel treatment strategies against cancer. One of the mechanisms by which tumors down-regulate the immune system is through the anergizing inactivation of helper T lymphocytes, resulting in the absence of T cell help to tumor-specific CTLs. Although T-cells specific for tumor associated antigens are detected in cancer patients they often are unresponsive. Reversal of the defects that block the cell cycle progression is mandatory for clonal expansion of tumor specific T cells during the administration of tumor vaccines. Reversal of the anergic state of tumor specific T cells is also critical for the sufficient expansion of such T cells ex vivo for adoptive immunotherapy. On the other hand, understanding the molecular mechanisms of anergy will greatly improve our ability to design novel clinical therapeutic approaches to induce antigen-specific tolerance and prevent graft rejection and graft-versus-host disease. Such treatment approaches will allow transplantation of bone marrow and solid organs between individuals with increasing HLA disparity and therefore expand the donor pool, enable reduction in the need for nonspecific immunosuppression, minimize the toxicity of chemotherapy, and reduce the risk of opportunistic infections.
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PMID:Helper T cell anergy: from biochemistry to cancer pathophysiology and therapeutics. 1143 20

Despite the identification of several oncogenic driver mutations leading to constitutive JAK-STAT activation, the cellular and molecular biology of myeloproliferative neoplasms (MPN) remains incompletely understood. Recent discoveries have identified underlying disease-modifying molecular aberrations contributing to disease initiation and progression. Here, we report that deletion of Nol3 (Nucleolar protein 3) in mice leads to an MPN resembling primary myelofibrosis (PMF). Nol3-/- MPN mice harbor an expanded Thy1+LSK stem cell population exhibiting increased cell cycling and a myelomonocytic differentiation bias. Molecularly, this phenotype is mediated by Nol3-/--induced JAK-STAT activation and downstream activation of cyclin-dependent kinase 6 (Cdk6) and MycNol3-/- MPN Thy1+LSK cells share significant molecular similarities with primary CD34+ cells from PMF patients. NOL3 levels are decreased in CD34+ cells from PMF patients, and the NOL3 locus is deleted in a subset of patients with myeloid malignancies. Our results reveal a novel genetic PMF-like mouse model and identify a tumor suppressor role for NOL3 in the pathogenesis of myeloid malignancies.
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PMID:A myeloid tumor suppressor role for NOL3. 2823 69