Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of a 70,000 dalton-heat shock protein (hsp70) is one of several heat shock proteins induced in HeLa cells during the incubation in medium containing zinc sulphate. The synthesis of hsp70 was increased in the presence of 200 microM zinc sulphate and above, but not at 100 microM zinc sulphate. On the other hand, the synthesis of metallothionein was activated in the presence of 100 microM zinc sulphate and above. Uptake of zinc into the cells depended on the concentration of zinc sulphate in the medium. The separation of intracellular zinc into three fractions by gel filtration chromatography; high molecular, metallothionein, and low molecular fractions, showed that zinc in the low molecular weight and metallothionein fractions was elevated in the presence of 100 microM zinc sulphate in the medium, whereas increase in the zinc content of the high molecular weight fraction occurred at 200 microM zinc sulphate and above. Inhibition of cell growth and cellular protein synthesis was also observed at 200 microM zinc sulphate and above, but not at 100 microM. From these findings, since the induction of hsp70 synthesis and inhibition of cell growth occurred concomitantly with the increase of zinc in the high and low molecular weight fractions, hsp70 seemed not to function in the detoxification of zinc, but it may participate in the repair of zinc-induced damage.
Mol Cell Biochem 1992 Jun 26
PMID:Characteristic induction of 70,000 da-heat shock protein and metallothionein by zinc in HeLa cells. 164 Sep 29

NADP-dependent glutamate dehydrogenase from Dictyostelium discoideum was purified 9300 fold with a yield of 4.6%. The enzyme is a hexamer of apparent molecular weight 294 kDa on Sephacryl S400 and a subunit molecular weight of 52 kDa as determined by SDS gel electrophoresis. The apparent Kms for alpha-ketoglutarate, NADPH and NH4+ are 1.2 mM, 9.7 microM and 2.2 mM respectively, and the purified enzyme has a broad pH optimum with a peak at pH 7.75. GTP has a slight stimulatory effect (22% at 83 microM) as does ADP (11% at 1 mM), and AMP is slightly inhibitory (9% at 1 mM) whereas adenosine, ATP and cAMP have little or no effect. Neither the Zn2+ chelating compound 1,10-phenanthroline nor EDTA have any effect on the enzyme while p-hydroxymercuribenzoic acid inhibits enzyme activity (50% at 80 microM) yet N-ethylmaleimide does not. In addition, the NADP-GDH activity varies little during the various stages of morphogenesis.
Mol Cell Biochem 1991 Jun 26
PMID:Purification and properties of the NADP-dependent glutamate dehydrogenase from Dictyostelium discoideum. 165 3

A new technique for uncoupling the cleavage and religation half-reactions of topoisomerase I at a specific site has been developed. The technique takes advantage of a suicidal DNA substrate to attain enzyme-mediated cleavage without concomitant religation. Efficient religation can be achieved, subsequently, by addition of an oligonucleotide capable of hybridising to the non-cleaved strand of the suicide DNA substrate. The technique was used to study the effect of different compounds on the half-reactions of topoisomerase I. It was shown that topoisomerase I-mediated cleavage was inhibited by NaCl concentrations higher than 200 mM, while the religation reaction seemed unaffected by concentrations as high as 3 M-NaCl. The divalent cations Mg2+, Ca2+ and Mn2+ were found to enhance the cleavage but not the religation reaction of topoisomerase I, whereas Cu2+ and Zn2+ inhibited both reactions. Furthermore, the effect of the anti-neoplastic agent, camptothecin, on the half-reactions of topoisomerase I was investigated. It was found that the drug did not affect the cleavage reaction of topoisomerase I at the studied site, while the religation reaction of the enzyme was inhibited. Camptothecin was found to stabilise the enzyme-DNA cleavage complex even when the drug was added after complex formation.
J Mol Biol 1991 Dec 05
PMID:New technique for uncoupling the cleavage and religation reactions of eukaryotic topoisomerase I. The mode of action of camptothecin at a specific recognition site. 166 Sep 29

Phosphoinositide-specific phospholipase C (PI-PLC) activity in whole homogenates of mouse pancreatic islets decreased 60-85% when the homogenates were incubated at 37 degrees C for 1 h in the presence of down to micromolar concentrations of Ca2+. Ca(2+)-induced inactivation was augmented by calmodulin, the phorbol ester 12-O-tetradecanoylphorbol 13-acetate in the presence of ATP-Mg, and by Mg2+. Inactivation was inhibited when ATP was removed and completely abolished by trifluoperazine and EGTA. Inactivation was not affected by the non-phosphorylating ATP analogue, AMP-PCP, GMP-PNP, glucose, Zn2+ or a series of protease inhibitors. These observations suggest that PI-PLC in broken cell preparations of pancreatic islets may be inactivated via phosphorylation by Ca(2+)-calmodulin-stimulated protein kinase and/or protein kinase C. Inactivation of PI-PLC was reversible. Reactivation started after approx. 2 h incubation, when the concentration of ATP in the homogenate was below 0.15 x 10(-6) M. PI-PLC activity returned to values approx. 25% higher than the initial values. PI-PLC inactivation via phosphorylation by the mentioned protein kinases may constitute a feedback control on the phosphoinositide response, attenuating subsequent diacylglycerol formation and/or Ca2+ mobilization by inositol trisphosphate.
Mol Cell Endocrinol 1991 Nov
PMID:Ca(2+)- and ATP-dependent reversible inactivation of pancreatic islet phosphoinositide-specific phospholipase C activity. 166 65

We have shown by site-directed mutagenesis that the sequence between positions -69 and -40 of the mouse alpha A-crystallin gene is crucial for tissue-specific gene expression in a transfected mouse lens epithelial cell line transformed with the early region of simian virus 40. Gel retardation experiments with synthetic oligodeoxynucleotides revealed a mouse lens nuclear protein which bound specifically to the palindromic sequence 5'-GGGAAATCCC-3' at positions -66 to -57 in the alpha A-crystallin promoter. By screening a bacteriophage lambda gt11 expression library of the transformed lens cells, we isolated a 2.5-kilobase-pair cDNA encoding a fusion protein which bound to this sequence and to the regulatory element of the major histocompatibility complex (MHC) class I gene. This cDNA hybridized to a 10-kilobase-pair polyadenylated RNA present in many different tissues, including lens. It encoded a protein, tentatively called alpha A-CRYBP1, containing at least two zinc fingers. alpha A-CRYBP1 is either homologous or very similar to the human nuclear proteins MBP-1 (Baldwin et al., Mol. Cell. Biol. 10:1406-1414, 1990), PRDII-BFI (Fan and Maniatis, Genes Dev. 4:29-42, 1990), and HIV-EP1 (Maekawa et al., J. Biol. Chem. 264:14591-14593, 1989), which bind to regulatory elements of the MHC class I, beta interferon, and human immunodeficiency virus genes, respectively. Our results suggest that the lens-specific alpha A-crystallin, MHC class I, beta interferon and other genes have a similar cis-acting DNA regulatory motif that shares alpha A-CRYBPI, MBP-1, PRDII-BF1, HIV-EP1, or other closely related proteins as trans-acting factors.
Mol Cell Biol 1990 Jul
PMID:Regulation of the mouse alpha A-crystallin gene: isolation of a cDNA encoding a protein that binds to a cis sequence motif shared with the major histocompatibility complex class I gene and other genes. 169 16

Zinc noncompetitively antagonizes N-methyl-D-aspartate (NMDA) receptor-mediated responses in cultured neurons. We investigated the mechanism of this inhibition by examining the effect of zinc on ligand binding to three distinct sites on the NMDA receptor in rat hippocampal membranes. Zinc dose-dependently inhibited both the association and dissociation of the NMDA channel blocker [3H]N-(1-[thienyl]cyclohexyl)piperidine ([3H]TCP) but had no effect on steady state levels of [3H]TCP binding. This suggests that zinc inhibits the receptor-gated access of [3H]TCP to its site in the ion channel but has no effect on the binding site itself. Zinc inhibition of [3H]TCP association was not mediated by an action at the NMDA recognition site, because zinc had no effect on NMDA-displaceable L-[3H]glutamate binding. On the other hand, zinc dose-dependently inhibited [3H]glycine binding by a noncompetitive interaction. Stoichiometric analysis of equilibrium binding data indicated the presence of two [3H]glycine binding sites/[3H]TCP binding site. Comparison of the potencies of zinc in inhibiting glycine-dependent [3H]TCP association and [3H]glycine binding suggests that blockade of only one of the two glycine sites is sufficient to prevent [3H]TCP association. We hypothesize that synaptically released zinc inhibits NMDA receptor-mediated responses by binding to a site on the receptor/channel complex, reducing glycine binding, and thereby decreasing what would otherwise be a tonically present action of endogenous extracellular glycine.
Mol Pharmacol 1990 Jul
PMID:Evidence that zinc inhibits N-methyl-D-aspartate receptor-gated ion channel activation by noncompetitive antagonism of glycine binding. 169 16

DNA polymerase beta (beta-pol) and its mRNA are maintained at constitutive levels during the cell cycle and during stages of cell growth in culture. To study biological consequences of variations in the level of this DNA repair enzyme and/or its mRNA, we prepared expression vectors in which cDNA for human beta-pol is inserted under the control of a metallothionein promoter (pMT) in the sense and antisense orientation, respectively, and these vectors then were used for stable transformation of mouse 3T3 cells. Vectors also contained the mouse DHFR gene, such that culture of transformants in medium with increasing concentrations of methotrexate resulted in amplification of inserted DNA. The levels of sense and antisense transcripts are strongly increased by culture of transformants in medium with 65 microM Zn2+, although some expression is detected even without Zn2+ induction. After five days of induction, the beta-pol level was about threefold higher in sense cells and about 10-fold lower in antisense cells than in parallel cultures without induction. The antisense line has a threefold increased cell doubling time in the presence of 65 microM Zn2+ compared with the absence of Zn2+. Zn2+ (65 microM) induction for the sense line results in normal growth for the first three days and, thereafter, a complete cessation of growth. Yet, these blocked cells remain fully viable. The results indicate that sudden deregulation of beta-pol expression alters cell growth in mouse 3T3 cells.
Somat Cell Mol Genet 1990 Jul
PMID:Deregulation of DNA polymerase beta by sense and antisense RNA expression in mouse 3T3 cells alters cell growth. 169 88

The effects of divalent metals, metal chelators (EDTA, EGTA) and sodium dodecyl sulfate were investigated on the phosphatase activity of isolated bovine brain calcineurin assayed in the absence (called intrinsic) and presence of calmodulin. Intrinsic phosphatase was increased by Mn2+, was unaffected by Mg2+, Ca2+, and Ba2+, and was markedly inhibited by Ni2+, Fe2+, Zn2+ and Cu2+. When assayed in the presence of calmodulin, many divalent metals (Ni2+, Zn2+, Pb2+, Cd2+), besides Mn2+, increased modestly the phosphatase activity at low concentrations (10-100 microM) and inhibited it markedly at high concentrations. Ca2(+)-calmodulin stimulated phosphatase activity was antagonized by Ni2+, Zn2+, Fe2+, Cu2+, Pb2+, at low concentrations (50 microM), and by Ba2+, Cd2+ at slightly higher concentrations (greater than 100 microM); Mn2+ and Co2+ (50 microM to 1 mM) in fact augmented it. EDTA and EGTA in a concentration and time dependent fashion inhibited the intrinsic phosphatase activity, particularly that of trypsinized calcineurin. SDS in low concentrations (0.005%) augmented the phosphatase activity and inhibited it at high concentrations. Mn2+ (+/- calmodulin) and Ca2+ only with calmodulin present increased the phosphatase activity assayed with low concentrations of SDS. The EDTA dependent inhibition of intrinsic phosphatase was almost abolished in assays containing SDS. Prior exposure of calcineurin to Mn2+ led to a high activity conformation state of calcineurin that was 'long-lived' or 'pseudo-irreversible'. Such Mn2(+)-activated state of calcineurin exhibited no discernible change in the affinity towards myelin basic protein or its inhibition by trifluoperazine. At alkaline pH, Mg2+ supported the intrinsic phosphatase activity, although to a lesser degree than Mn2+. The latter cation, compared to Mg2+ and Ni2+, was also a more powerful stimulator of the calcineurin phosphatase assayed with histone (III-S) and myosin light chain as substrates.
Mol Cell Biochem 1990 Sep 03
PMID:Divalent cation effects on calcineurin phosphatase: differential involvement of hydrophobic and metal binding domains in the regulation of the enzyme activity. 170 Oct 13

RNase P is a multi-subunit enzyme responsible for the accurate processing of the 5' terminus of all tRNAs. The RNA subunit from Clostridium sporogenes has been partially purified and characterized. The RNA is approximately 400 nucleotides long and makes a precise endonucleolytic cleavage at the mature 5' terminus of tRNA. The RNA requires moderate concentrations of Mg2+ (20 mM) and relatively high concentrations of NH4Cl (800 mM) for optimal activity. Mn2+ effectively substitutes for Mg2+ at 2 mM. Zn2+, Ni2+, Ca2+, and Co2+ are ineffective at stimulating activity. Monovalent ions are, in general, more effective the greater the ionic radius (NH+4 greater than Cs greater than Rb greater than K greater than Na). In contrast to the activity of Bacillus subtilis, C. sporogenes RNase P RNA is significant more active in (NH4)2SO4 than in NH4Cl.
Mol Microbiol 1990 Aug
PMID:Purification and characterization of RNase P from Clostridium sporogenes. 170 96

The action of zinc on chloride currents evoked by gamma-aminobutyric acid (GABA) was examined on cultured hippocampal neurons using whole cell voltage clamp and outside-out patch recording. Zn (5-30 microM) noncompetitively blocked responses evoked by GABA (0.5-100 microM), but did not affect either the time-to-peak or desensitization of the macroscopic current. In outside-out patches, Zn had no effect on the mean conductance or lifetime of the 19 or 30 pS openings of the GABA channel; however, the frequency of channel opening was markedly decreased in a voltage-independent manner. Zn inhibition of GABA responses appeared to be independent of the benzodiazepine binding site as Zn was effective in the presence of either diazepam or Ro15-1788, a competitive antagonist of benzodiazepine agonists and inverse agonists. In contrast to prior reports, Zn also inhibited GABA currents in a similar manner on cultured superior cervical ganglion neurons. These results suggest that Zn acts at an extracellular site on the GABAA receptor complex, which is distinct from either the GABA or benzodiazepine binding sites. The structural similarity of the Cys-Cys loop of the alpha and gamma GABAA receptor subunits to some Zn-binding proteins suggests one possible region for a Zn binding site.
Mol Pharmacol 1991 Mar
PMID:Noncompetitive inhibition of gamma-aminobutyric acidA channels by Zn. 170 68


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