Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In heme-deficient reticulocyte lysates, protein synthesis initiation is inhibited due to the activation of a heme-regulated protein kinase which blocks protein synthesis by the specific phosphorylation of the alpha-sub-unit of eukaryotic initiation factor 2 (eIF-2 alpha). The restoration of synthesis requires both hemin and glucose-6-P (Ernst, V., Levin, D. H., and London, I. M. (1978) J. Biol. Chem. 253, 7163-7172). The sugar phosphate fulfills two functions in initiation: (i) the generation of NADPH, and (ii) an effector function in some step in initiation. This latter effect is readily demonstrated in lysates depleted of low molecular weight components by filtration in dextran gels. In gel-filtered lysates, linear protein synthesis is sustained only by the addition of both hemin (20 microM) and glucose-6-P (or 2-deoxyglucose-6-P) (50-500 microM). The omission of either component gives rise to inhibitions which are characterized by the activation of heme-regulated eIF-2 alpha kinase and the concomitant phosphorylation of both endogenous heme-regulated eIF-2 alpha kinase and endogenous eIF-2 alpha, indicating that glucose-6-P is involved in the regulation of heme-regulated eIF-2 alpha kinase. In support of this, we find (a) that gel-filtered lysates incubated with hemin but depleted of glucose-6-P produce sufficient heme-regulated eIF-2 alpha kinase to inhibit protein synthesis when mixed with normal hemin-supplemented lysates; (b) the inhibitions of protein synthesis produced by heme-regulated eIF-2 alpha kinase generated either in glucose-6-P-depleted lysates or heme-deficient lysates are reversed by added eIF-2; and (c) the eIF-2 alpha kinase activities formed in the absence of either hemin or glucose-6-P are both neutralized by an anti-heme-regulated eIF-2 alpha kinase antiserum. We conclude that the physiological activation of heme-regulated eIF-2 alpha kinase is controlled by both hemin and glucose-6-P.
 ...
PMID:Effects of glucose 6-phosphate and hemin on activation of heme-regulated eIF-2 alpha kinase in gel-filtered reticulocyte lysates. 673 41

Cl- conductance of the apical membrane of airway epithelial cells has properties of a passive diffusion mechanism but is decreased by inhibition of oxidative metabolism. Recent reports that cAMP-dependent Cl- conductance also requires ATP at the intracellular domains of the cystic fibrosis transmembrane conductance regulator (CFTR) suggests that ATP concentration could mediate metabolic regulation of Cl- conductance. However, metabolic inhibitors affect processes other than ATP free energy levels, including notably the metabolic pathways that set the redox potential of pyridine nucleotides within the cell. We have investigated the possibility that CFTR-mediated Cl- conductance is affected by the ratio of oxidized to reduced intracellular pyridine nucleotides. CFTR was expressed in airway and heterologous cells and studied under whole cell voltage clamp conditions, which permitted the intracellular NAD(P)+/NAD(P)H ratio to be varied independently of ATP concentration. In three cell types expressing CFTR, whole cell dialysis with reduced pyridine nucleotides inhibited activation of Cl- currents by forskolin and 8-(4-chlorophenylthio)-cAMP (CPT-cAMP), whereas dialysis with oxidized pyridines increased both basal and stimulated CFTR-mediated Cl- conductance. In cell-attached membrane patches, the open probability of 5-6-picosiemens Cl- channels that had been activated by forskolin and CPT-cAMP was further and reversibly increased by permeant oxidants. Neither swelling-induced whole cell K+ currents in CFTR-expressing cells nor swelling-induced whole cell Cl- currents in multidrug resistance protein-expressing cells were affected by NADPH. Pyridine nucleotide redox potential had little effect on phosphorylation of histone by protein kinase A. We conclude that CFTR Cl- conductance function can be modulated by pyridine nucleotide redox potential. This effect points to the existence of a mechanism or mechanisms by which cytosolic nucleotides other than ATP can affect plasma membrane Cl- conductance and may help explain how a passive ion conductance is linked to cellular energy metabolism.
 ...
PMID:Pyridine nucleotide redox potential modulates cystic fibrosis transmembrane conductance regulator Cl- conductance. 751 Jun 95

Selective antagonists of myosin light chain kinase (MLCK) [e.g. ML-7; 1-(5-iodonaphthalene-1-sulphonyl)-1H-hexahydro-1,4-diazepine hydrochloride] were found to inhibit superoxide (O2-) release from stimulated neutrophils. The concentrations of ML-7 that were inhibitory were substantially lower than those reported for a selective antagonist of protein kinase C [i.e. H-7; 1-(5-isoquinolinesulphonyl)-2-methylpiperazine dihydrochloride]. ML-7 also reduced the phosphorylation of the 47 kDa subunit of the NADPH-oxidase system (p47-phox) and blocked translocation of this protein to the Triton X-100-insoluble fraction in stimulated cells. Interestingly, ML-7 also inhibited O2- production in a cell-free system derived from neutrophils at concentrations similar to those that were effective in vivo. This cell-free system does not require ATP and is insensitive to all other inhibitors of protein kinases tested, including some highly effective against MLCK (i.e. staurosporine). Thus, the data suggest that ML-7 does not block O2- release by inhibiting a protein kinase but instead may interact directly with a subunit of the oxidase. The binding site for ML-7 may provide a valuable target for inhibiting the inflammatory properties of phagocytic leucocytes by naphthalenesulphonamides designed to lack activity against protein kinases.
 ...
PMID:Naphthalenesulphonamides block neutrophil superoxide production by intact cells and in a cell-free system: is myosin light chain kinase responsible for these effects? 757 84

In mammalian cells, the guanine nucleotide exchange factor (GEF or eIF-2B) is a key regulator of polypeptide chain initiation. The exchange of GDP bound to chain initiation factor 2 (eIF-2) for GTP by GEF is a rate limiting step in protein synthesis. The multisubunit characteristics of GEF suggest that this protein is composed of several distinct structural and functional domains, and is regulated by allosteric means and by phosphorylation. The activity of GEF may be regulated indirectly by the phosphorylation state of the smallest subunit of eIF-2 (alpha-subunit). On the other hand, phosphorylation of the largest subunit of GEF (82-kD subunit) by casein kinase (CK) I or II stimulates GDP/GTP exchange. GEF contains NADPH which is required for structural integrity of the protein. Upon stimulation of cells by insulin and growth factors, allosteric activation of GEF by sugar phosphates and other effector molecules may also play an important role in the regulation of polypeptide chain initiation. In this article, recent information about structure-function relationship of eIF-2 and GEF in nucleotide exchange and the regulatory mechanisms that influence the rate of polypeptide chain initiation under various physiological and pathological conditions are presented.
 ...
PMID:Translational control of eukaryotic gene expression. Role of the guanine nucleotide exchange factor and chain initiation factor-2. 758 45

The catalytic domain of 3-hydroxy-3-methylglutaryl-CoA reductase isoform 1 (HMGR1cd) from Arabidopsis thaliana has been expressed in Escherichia coli in a catalytically active form and purified. The high efficiency of the bacterial expression system together with the simplicity of the purification procedure used in this study resulted in the attainment of large quantities of pure enzyme (about 5 mg/l culture) with a final specific activity of up to 17 U/mg. This specific activity is higher than that reported to date for any 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) purified from a plant source. HMGR1cd activity was completely blocked by the HMGR inhibitor mevinolin (IC50 = 12.5 nM). No significant differences were observed between the Km values of HMGR1cd for NADPH (71 +/- 7 microM) and (S)-3-hydroxy-3-methylglutaryl-CoA (8.3 +/- 1.5 microM) and those of pure HMGR preparations obtained from different plant sources. The purified HMGR1cd was reversibly inactivated by phosphorylation at a single site by Brassica oleracea HMGR kinase A, which is functionally related to the mammalian AMP-activated protein kinase. The site of phosphorylation is Ser577 in the complete sequence of A. thaliana HMGR1. The results in this paper represent the first evidence that a higher plant HMGR is regulated by direct phosphorylation, at least in a cell-free system. Our results also reinforce the view that the AMP-activated protein kinase/SNF1 family is an ancient and highly conserved protein kinase system.
 ...
PMID:Bacterial expression of the catalytic domain of 3-hydroxy-3-methylglutaryl-CoA reductase (isoform HMGR1) from Arabidopsis thaliana, and its inactivation by phosphorylation at Ser577 by Brassica oleracea 3-hydroxy-3-methylglutaryl-CoA reductase kinase. 758 95

Adrenaline has recently been shown to stimulate both glucose metabolism and H2O2 release by macrophages but the activity of the key pentose phosphate pathway enzyme, glucose-6-phosphate dehydrogenase (which generates the NADPH crucial for the reduction of molecular oxygen), was reduced under these conditions [Costa Rosa, Safi, Cury and Curi (1992) Biochem. Pharmacol. 44, 2235-2241]. We report here that adrenaline activates another NADPH-producing enzyme, NADP(+)-dependent 'malic' enzyme, while also inhibiting glucose-6-phosphate dehydrogenase, via cyclic AMP-dependent protein kinase (PKA) activation. Regulation of glucose-6-phosphate dehydrogenase activity by PKA has not been reported elsewhere. The sparing of some glucose from pentose phosphate pathway consumption may be important in the provision of glycerol 3-phosphate which in the macrophage may be required for new phospholipid synthesis. Glutamine oxidation was also stimulated by adrenaline thus providing increased substrate (malate) for NADP(+)-dependent 'malic' enzyme and therefore shifting some of the burden of NADPH production from glucose to glutamine metabolism. We also report a novel synergistic effect of adrenaline and some bacterial products and/or gamma-interferon in stimulating secretory and metabolic pathways in macrophages which may be a part of a larger network of signals that lead to enhanced macrophage activity.
 ...
PMID:Effect of adrenaline and phorbol myristate acetate or bacterial lipopolysaccharide on stimulation of pathways of macrophage glucose, glutamine and O2 metabolism. Evidence for cyclic AMP-dependent protein kinase mediated inhibition of glucose-6-phosphate dehydrogenase and activation of NADP+-dependent 'malic' enzyme. 765 15

Several novel protein kinases are known to be rapidly activated in neutrophils stimulated with the chemoattractant fMet-Leu-Phe (fMLP). These kinases include a histone H4 protein kinase and several renaturable kinases with molecular masses of about 69, 63, 49, and 40 kDa. The renaturable kinases can catalyze the phosphorylation of a peptide that corresponds to residues 297-331 of the 47-kDa subunit of the NADPH-oxidase system (p47-phox). Previous studies have indicated that the activation of all of these protein kinases involves an uncharacterized stimulatory pathway and/or novel second messenger. The studies reported herein were undertaken to determine if phosphatidylinositol 3-kinase (PI3-K) is a component of this pathway. We report that certain chromosome derivatives (e.g. 2-(4-morpholinyl)-8-phenylchromone (LY294002)) and wortmannin, which inhibit PI3-K by distinct mechanisms, blocked activation of all of these novel kinases. These antagonists also inhibited the phosphorylation of p47-phox (about 50%) and O2.- release (about 80%) in cells stimulated with fMLP, but not with 4 beta-phorbol 12-myristate 13-acetate. A strong correlation exists between the amounts of these antagonists required to produce 50% inhibition of PI3-K in vitro and O2.- release in vivo. In contrast, a single atom substitution of LY294002 produced a compound (LY303511) that did not inhibit PI3-K. Compound LY303511 did not appreciably inhibit the activation of the novel protein kinases or O2.- generation. These data strongly suggest that PI3-K is involved in the activation of several novel protein kinases in neutrophils, one or more of which may be involved in O2.- release.
 ...
PMID:Antagonists of phosphatidylinositol 3-kinase block activation of several novel protein kinases in neutrophils. 774 8

Nimesulide, the prototype of a new class of anti-inflammatory drugs, dose-dependently decreases the production of the superoxide anion (O2-.) in N-formyl-methionyl-leucyl-phenylalanine (fMLP)- and in phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocytes. The inhibition of O2-. is possibly related to its inhibitory effect on polymorphonuclear leukocyte cytosolic phosphodiesterase type IV (IC50 = 39 +/- 2 microM), to the related increase in cAMP (P < 0.01 at 1 microM) and the subsequent increase in protein kinase A activity. In fact H-89, a specific protein kinase A inhibitor, counteracts the inhibitory effect of nimesulide on O2-. production by fMLP and PMA. The activation of protein kinase A may prompt the phosphorylation of a number of substrates, thus inhibiting the assembly of NADPH-oxidase in the plasma membrane. Accordingly, nimesulide decreases PMA-induced assembly of NADPH-oxidase in polymorphonuclear leukocytes plasma membranes by about 35%. Protein kinase A activation may also interfere with chemotaxis. Nimesulide inhibits stimulated chemotaxis and the effect is decreased by H-89. Inhibition of phosphodiesterase type IV may explain many of nimesulide's effects.
 ...
PMID:Nimesulide decreases superoxide production by inhibiting phosphodiesterase type IV. 780 66

Thioredoxin (Trx) catalyzes thiol-disulfide oxidoreductions. We and others recently showed that human Trx could function as an autocrine growth factor for human lymphoid cells immortalized by the human T-lymphotrophic virus type I or the Epstein-Barr virus. Here we report that reduced Trx from Escherichia coli generated by NADPH and thioredoxin reductase increases the proliferation of an Epstein-barr virus(+)-B cell line 1G8, which constitutively produces low amounts of human Trx. This proliferative effect involved the activation of protein kinase C through its translocation to the membrane. Staurosporin and calphostin C, two inhibitors of protein kinase C, but not of H8, a protein kinase A inhibitor, were able to block Trx-dependent proliferation. The addition of Trx to 1G8 cells resulted in the formation of inositol 1,4,5-triphosphate and sn-1,2-diacylglycerol by a phosphoinositide-specific phospholipase C, as well as increased free calcium concentration. Diacylglycerol showed a biphasic increase; the first phase, corresponding to an early peak (30 s) of inositol 1,4,5-triphosphate and a second larger, prolonged phase. The second phase was inhibited by propranolol, a specific inhibitor of phosphohydrolase, indicating that it is most likely derived from phosphatidylcholine hydrolysis by the sequential action of phospholipase D and phosphatidic acid phosphohydrolase. Our data suggest that enhanced phosphoinositide-specific phospholipase C activity induced by the dithiol form of Trx in 1G8 cells is associated to protein kinase C activation, and thus plays a role in the permanent growth of Epstein-Barr virus-infected B cells.
 ...
PMID:Thioredoxin increases the proliferation of human B-cell lines through a protein kinase C-dependent mechanism. 796 46

The effect of an inhibitor of protein kinase, HA1077 [1-(5-isoquinolinesulfonyl)-homopiperazine HCl], and its hydroxylated metabolite, HA1100, on the activation of NADPH oxidase in human neutrophils were studied. Cells were preincubated with each drug for 10 min and then activated by treatment with phorbol myristate acetate (PMA) or formylmethionyl leucyl phenylalanine (FMLP). After activation, the rate of superoxide dismutase-inhibitable reduction of cytochrome c was estimated. HA1077 and HA1100 inhibited the PMA-induced production of O2- by neutrophil NADPH oxidase in a concentration-dependent manner (IC50 = 15 and 24 microM, respectively). The sensitivity of the FMLP-induced production of O2- to these drugs was similar. The production of O2- in 1,25-dihydroxyvitamin D3-treated HL-60 cells, which differentiated to macrophage-like cells, was also inhibited by the drugs. The extent of inhibition by HA1077 was almost the same as that by a calmodulin inhibitor (W-7) and by inhibitors of protein kinase (H-7 and H-8). In a cell-free lysate of neutrophils, the NADPH-dependent production of O2- can be induced by sodium dodecyl sulfate (SDS). HA1077 at 100 microM had only a weak inhibitory effect on the cell-free, SDS-induced production of O2-, an indication that HA1077 inhibits the activation of NADPH oxidase, not the actual activity. The effects of H-7 and H-8 were similar to that of HA1077, whereas W-7 inhibited the production of O2- by the cell-free extract of HL-60 cells. This action of HA1077 could explain, in part, its ability to protect neuronal cells from death after ischemia.
 ...
PMID:Inhibition by the protein kinase inhibitor HA1077 of the activation of NADPH oxidase in human neutrophils. 824 Apr


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>