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)

An enzyme able to cleave dinucleoside triphosphates has been purified 3,750-fold from Saccharomyces cerevisiae. Contrary to the enzymes previously shown to catabolize Ap4A in yeast, this enzyme is a hydrolase rather than a phosphorylase. The dinucleoside triphosphatase molecular ratio estimated by gel filtration is 55,000. Dinucleoside triphosphatase activity is strongly stimulated by the presence of divalent cations. Mn2+ displays the strongest stimulating effect, followed by Mg2+, Co2+, Cd2+, and Ca2+. The Km value for Ap3A is 5.4 microM (50 mM Tris-HCl [pH 7.8], 5 mM MgCl2, and 0.1 mM EDTA; 37 degrees C). Dinucleoside polyphosphates are substrates of this enzyme, provided that they contain more than two phosphates and that at least one of the two bases is a purine (Ap3A, Ap3G, Ap3C, Gp3G, Gp3C, m7Gp3A, m7Gp3G, Ap4A, Ap4G, Ap4C, Ap4U, Gp4G, and Ap5A are substrates; AMP, ADP, ATP, Ap2A, and Cp4U are not). Among the products, a nucleoside monophosphate is always formed. The specificity of cleavage of methylated dinucleoside triphosphates and the molecular weight of dinucleoside triphosphatase indicate that this enzyme is different from the mRNA decapping enzyme previously characterized (A. Stevens, Mol. Cell. Biol. 8:2005-2010, 1988).
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PMID:Isolation and characterization of a dinucleoside triphosphatase from Saccharomyces cerevisiae. 165 9

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+/calmodulin-dependent cyclic nucleotide (AMP) phosphodiesterase activity in rat liver cytosol was investigated. The addition of Ca2+ (50 microM) and calmodulin 160 U/ml in the enzyme reaction mixture caused a significant increase in cyclic AMP phosphodiesterase activity. This increase was inhibited by the presence of regucalcin (0.5-3.0 microM); the inhibitory effect was complete at 1.0 microM. Regucalcin (1.0 microM) did not have an appreciable effect on basal activity without Ca2+ and calmodulin. The inhibitory effect of regucalcin was still evident even at several fold higher concentrations of calmodulin (160-480 U/ml). However, regucalcin (1.0 microM) did not inhibit Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity in the presence of 100 and 200 microM Ca2+ added. Meanwhile, Cd2+ (25-100 microM)-induced decrease in Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity was not reversed by the presence of regucalcin (1.0 microM). The present results suggest that regucalcin can regulate Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity due to binding Ca2+ in liver cells.
Mol Cell Biochem 1991 Jul 24
PMID:Inhibitory effect of calcium-binding protein regucalcin on Ca2+/calmodulin-dependent cyclic nucleotide phosphodiesterase activity in rat liver cytosol. 165 6

The thermolabile glucocorticoid receptor (GR) in fibroblasts from a patient with familial glucocorticoid resistance (FGR) was characterized by solution hybridization, Northern blot analysis and Western immunoblotting using an hGR and cRNA probe and a GR specific monoclonal antibody. Specific DNA binding was measured by binding of cytosolic GR to mouse mammary tumour virus (MMTV) DNA. Northern blot analysis of total cellular RNA isolated from the fibroblasts showed hybridization of the hGR probe to 7.0 and 6.1 kb RNA species. Basal expression of hGR mRNA was 1.8 times higher in fibroblasts derived from the patient compared to control fibroblasts as assayed by solution hybridization. Even though nonsignificant, dexamethasone treatment maximally caused at 60% down-regulation of GR mRNA in normal fibroblasts after 12 h but only a 40% down-regulation in fibroblasts from the patient. In both cases, the initial mRNA values were restored after 72 h. No difference in GR mRNA stability was observed between fibroblasts from the patient and from controls. The induction of the glucocorticoid-regulated gene metallothionein IIA (MTIIA) by dexamethasone and cadmium sulphate was studied at different temperatures using a cRNA probe for human MTIIA. At elevated temperatures, cadmium sulphate but not dexamethasone increased MTIIA mRNA levels approximately three-fold in fibroblasts from the patient, whereas in normal fibroblasts regardless of temperature both cadmium sulphate and dexamethasone increased MTIIA mRNA levels approximately three- and two-fold, respectively. Cytosolic GR from FGR-fibroblasts showed an increased specific binding to MMTV DNA at 4 degrees C. These data support our previous findings of a thermolabile GR, probably due to a defect intrinsic to the GR protein, in this patient with primary cortisol resistance and indicate a compensatory mechanism at the transcriptional level of GR expression. The data also indicate a receptor defect affecting specific DNA binding in vitro.
J Steroid Biochem Mol Biol 1991 Nov
PMID:Regulation of glucocorticoid receptor expression in cultured fibroblasts from a patient with familial glucocorticoid resistance. 165 67

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

The structural gene for the Bacillus stearothermophilus glycogen branching enzyme (glgB) was cloned in Escherichia coli. Nucleotide sequence analysis revealed a 1917 nucleotide open reading frame (ORF) encoding a protein with an Mr of 74787 showing extensive similarity to other bacterial branching enzymes, but with a shorter N-terminal region. A second ORF of 951 nucleotides encoding a 36971 Da protein started upstream of the glgB gene. The N-terminus of the ORF2 gene product had similarity to the Alcaligenes eutrophus czcD gene, which is involved in cobalt-zinc-cadmium resistance. The B. stearothermophilus glgB gene was preceded by a sequence with extensive similarity to promoters recognized by Bacillus subtilis RNA polymerase containing sigma factor H (E - sigma H). The glgB promoter was utilized in B. subtilis exclusively in the stationary phase, and only transcribed at low levels in B. subtilis spoOH, indicating that sigma factor H was essential for the expression of the glgB gene in B. subtilis. In an expression vector, the B. stearothermophilus glgB gene directed the synthesis of a thermostable branching enzyme in E. coli as well as in B. subtilis, with optimal branching activity at 53 degrees C.
Mol Gen Genet 1991 Nov
PMID:Molecular cloning and nucleotide sequence of the glycogen branching enzyme gene (glgB) from Bacillus stearothermophilus and expression in Escherichia coli and Bacillus subtilis. 174 26

Induction of metallothionein by cadmium in catfish was a dose-dependent, transcriptionally-controlled process. Metallothionein mRNA was detected after Cd-exposure. Chronic doses produced more metallothionein than a single acute dose. Zn and Cu induced metallothionein to a lower extent compared to Cd. A few other low molecular weight proteins were induced in cadmium-exposed catfish liver, besides metallothionein. Isoelectric point of catfish metallothionein was 3.9. The rate of depletion of Cd and metallothionein was very slow from liver and almost unchanged from kidney following its induction by cadmium.
Mol Cell Biochem 1991 Nov 13
PMID:Induction and turnover of catfish (Heteropneustes fossilis) metallothionein. 177 Sep 43

The purified Ca2+/Mg2+ ATPase from rat heart plasma membrane was activated by Ca2+ and Mg2+ with Ka values of 1.47 mM and 2.51 mM, respectively; other divalent cations also activated the enzyme but to a lesser extent. Divalent cations like Cu2+, Zn2+, Ni2+, Cd2+ were potent inhibitors of the enzyme activity in the presence of Ca2+ or Mg2+ whereas Na+, K+ or HCO3- did not affect the Ca2+/Mg2+ ATPase activity; the pH optima was 8.5. The enzyme hydrolyzed ATP with a Km of 0.34 mM for Ca2+ ATPase and 0.48 mM for Mg2+ ATPase; various nucleoside triphosphate such as ITP, CTP, GTP, and UTP were also hydrolyzed. Phospholipase A and C as well as neuraminidase decreased the Ca2+/Mg2+ ATPase activity whereas phospholipase D was ineffective. The purified Ca2+/Mg2+ ATPase was found to bind ATP-r-35S with two affinities; the KD values were 50.9 +/- 0.8 and 1160 +/- 198 nM and the Bmax values were 8.71 +/- 0.16 and 145 +/- 9.7 nmol/mg protein for high and low affinity sites, respectively. Treatment of the enzyme preparation with phospholipases and neuraminidase did not affect the ATP-r-35S binding. Ca2+ was also found to bind with Ca2+/Mg2+ ATPase with a KD of 0.384 mM and a Bmax of 1.85 mumol/mg protein; Ni2+, Mn2+, Zn2+ at 1 mM concentrations inhibited the Ca2+ binding but Mg2+ and verapamil were without effect. Phospholipase A and neuraminidase decreased the Ca2+ binding by 20-30%; this indicated that Ca2+ binding with the purified enzyme may be partly due to the phospholipids and sialic acid residues associated with the enzyme. These results show that the purified Ca2+/Mg2+ ATPase is a Ca2+ binding glycoprotein having two binding sites for ATP. Furthermore, this study suggests that phospholipids associated with purified Ca2+/Mg2+ ATPase are required for maximal activity.
Mol Cell Biochem 1991 Oct 16
PMID:Characterization of the purified rat heart plasma membrane Ca2+/Mg2+ ATPase. 183 90

SR 33557 represents a new class of compounds (indolizine sulfone) that inhibit L-type Ca2+ channels. [3H]SR 33557 has been shown to bind with high affinity (Kd congruent to 0.36 nM, calculated from saturation isotherms and association/dissociation kinetics) to a single class of sites in a purified preparation of rat cardiac sarcolemmal membranes. The binding was found to be saturable and reversible. The maximal binding capacity was in approximately 1:1 stoichiometry with that of other Ca2+ channel antagonists. Various divalent cations (Mg2+, Mn2+, Ca2+, Ba2+, and Cd2+) were shown to inhibit specific [3H]SR 33557 binding, with Cd2+ being the most potent. Among several receptor or channel ligands (including omega-conotoxin and Na+ and K+ channel modulators), only the L-type Ca2+ channel antagonists were found to displace [3H]SR 33557. However, dihydropyridines, phenylalkylamines, benzothiazepines, and diphenylbutylpiperidines were found to inhibit [3H]SR 33557 in a noncompetitive manner as demonstrated by displacement and saturation experiments in addition to dissociation kinetics. From these results, we suggest that SR 33557 binds with high affinity to a unique site on the L-type Ca2+ channel found in rat cardiac sarcolemmal membranes.
Mol Pharmacol 1991 Jan
PMID:Characterization of the slow calcium channel binding sites for [3H]SR 33557 in rat heart sarcolemmal membranes. 184 21

Equilibrium binding studies with the sigma receptor ligand [3H]1,3-di(2-tolyl)guanidine ([3H]DTG) demonstrated two high affinity binding sites in membranes prepared from guinea pig brain. The apparent Kd values of DTG for sites 1 and 2 were 11.9 and 37.6 nM, respectively. The corresponding Bmax values were 1045 and 1423 fmol/mg of protein. Site 1 had high affinity for (+)-pentazocine, haloperidol, (R)-(+)-PPP, carbepentane, and other sigma ligands, suggesting a similarity with the dextromethorphan/sigma 1 binding site described by Musacchio et al. [Life Sci. 45:1721-1732 (1989)]. Site 2 had high affinity for DTG and haloperidol (Ki = 36.1 nM) and low affinity for most other sigma ligands. Kinetic experiments demonstrated that [3H]DTG dissociated in a biphasic manner from both site 1 and site 2. DTG and haloperidol increased the dissociation rate of [3H]DTG from site 1 and site 2, demonstrating the presence of pseudoallosteric interactions. Inorganic calcium channel blockers such as Cd2+ selectively increased the dissociation rate of [3H]DTG from site 2, suggesting an association of this binding site with calcium channels.
Mol Pharmacol 1991 Feb
PMID:Labeling by [3H]1,3-di(2-tolyl)guanidine of two high affinity binding sites in guinea pig brain: evidence for allosteric regulation by calcium channel antagonists and pseudoallosteric modulation by sigma ligands. 184 95

We investigated DNA damage caused by carcinogenic metals in a murine sarcoma virus (MuSV)-based mutagenicity assay in which mutations targeted to v-mos expression can be selected. Nickel chloride treatment of NRK cells (termed 6m2 cells) infected with MuSVts110, a retrovirus conditionally defective in viral RNA splicing and cell transformation, caused the outgrowth of transformed "revertants" with changes in the MuSVts110 RNA splicing phenotype. Cadmium and chromium treatment of 6m2 cells resulted in the selection of a second class of revertants with what appeared to be frameshift mutations allowing the translation of a readthrough gag-mos protein. In both classes of metal-induced revertants, viral gene expression was distinct from that observed in revertants arising in untreated 6m2 cultures, arguing that metal treatment did not simply enhance the rate of spontaneous reversion. In one representative nickel revertant line the operative nickel-induced mutation affecting MuSVts110 RNA splicing was a duplication of 70 bases surrounding the 3' splice site. The effect of this mutation was to direct splicing to the most downstream of the duplicated 3' sites and concomitantly relax its characteristic thermosensitivity. These data establish the mutagenic potential of nickel and provide the first example of a defined nickel-induced mutation in a mammalian gene.
Mol Carcinog 1991
PMID:Nickel mutagenesis: alteration of the MuSVts110 thermosensitive splicing phenotype by a nickel-induced duplication of the 3' splice site. 184 87


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