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Results for “protein synthesis”

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At least 19 recordsLinked to original sources
PubMed1994

Involvement of de Novo Protein Synthesis, Protein Kinase, Extracellular Ca2+, and Lipoxygenase in Arachidonic Acid Induction of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Genes and Isoprenoid Accumulation in Potato (Solanum tuberosum L.).

A series of inhibitors were tested to determine the participation of de novo protein synthesis, protein kinase activity, extracellular Ca2+, and lipoxygenase activity in arachidonic acid elicitation of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene expression and sesquiterpene phytoalexin biosynthesis in potato (Solanum tuberosum L. cv Kennebec). Gene-specific probes were used to discriminate effects on the expression of two HMGR genes (hmg1 and hmg2) that respond differentially in tuber tissue following wounding or elicitor treatment. Inhibition of protein synthesis with cycloheximide completely blocked arachidonate-induced hypersensitive necrosis and browning, including HMGR gene induction and phytoalexin accumulation. This suggests that proteins necessary for coupling arachidonic acid reception to HMGR mRNA accumulation are either rapidly turned over or not present constitutively and are induced following elicitor treatment. Staurosporin, a potent inhibitor of protein kinases, and ethyleneglycol-bis([beta]-aminoethyl ether)-N,N[prime]-tetraacetic acid, a Ca2+ chelator, inhibited arachidonate-induction of hmg2 gene expression and phytoalexin accumulation but did not inhibit the wound-induced expression of hmg1. However, staurosporin inhibited arachidonate's suppression of hmg1 gene expression. Eicosatetraynoic acid, a lipoxygenase inhibitor that suppresses elicitor-induced phytoalexin accumulation, also inhibited arachidonate's suppression of hmg1 and induction of hmg2. The results indicate that arachidonate's suppression of hmg1 and activation of hmg2 depend on a common intermediate or set of intermediates whose generation is sensitive to the inhibitors tested.

Journal Article↗
PubMed1998

Effects of genistein and staurosporine on angiotensin II-induced DNA synthesis, protein synthesis and mitogen-activated protein kinase activation in vascular smooth muscle cells.

This study examines the effects of protein kinase inhibitors and activator on angiotensin II-induced DNA synthesis and protein synthesis of rat aortic smooth muscle cells. In quiescent confluent cells, angiotensin II induced a concentration-dependent increase in thymidine incorporation and leucine incorporation. The tyrosine kinase inhibitor genistein caused an inhibition of the angiotensin II-induced DNA synthesis but not of the agent-induced protein synthesis. The protein kinase C inhibitors staurosporine and calphostin C caused an inhibition of the angiotensin II-induced protein synthesis but not of the agent-induced DNA synthesis. The protein kinase C activator phorbol 12-myristate 13-acetate stimulated protein synthesis. Angiotensin II stimulated mitogen-activated protein (MAP) kinases and the angiotensin II-induced MAP kinase activation was inhibited by genistein but not by staurosporine. These findings suggest that angiotensin II-induced DNA synthesis is at least partly mediated via protein-tyrosine phosphorylation and angiotensin II-induced protein synthesis is at least partly mediated by activation of protein kinase C. It seems likely that MAP kinase activation is involved in DNA synthesis but not in protein synthesis induced by angiotensin II.

Angiotensin II↗
PubMed1966

Enhancement of RNA synthesis, protein synthesis, and abscission by ethylene.

Ethylene stimulated RNA and protein synthesis in bean (Phaseolus vulgaris L. var. Red Kidney) abscission zone explants prior to abscission. The effect of ethylene on RNA synthesis and abscission was blocked by actinomycin D. Carbon dioxide, which inhibits the effect of ethylene on abscission, also inhibited the influence of ethylene on protein synthesis. An aging period appears to be essential before bean explants respond to ethylene. Stimulation of protein synthesis by ethylene occurred only in receptive or senescent explants. Treatment of juvenile explants with ethylene, which has no effect on abscission also has no effect on protein synthesis. Evidence in favor of a hormonal role for ethylene during abscission is discussed.

Journal Article↗
PubMedDate not supplied

Characteristics of lead adaptation in a rat kidney cell line. II. Effect on DNA synthesis, protein synthesis, and gene expression.

The effects of adaptation of normal rat kidney cells (NRK 52-E) to growth in 5 or 10 microM lead nitrate on the rates of DNA synthesis and on the rate and pattern of protein synthesis was studied. The rate of [3H]thymidine incorporation into DNA was increased in normal cells, but remained unchanged in one lead-adapted cell line (only 5 microM NRK studied). Increased rates of [3H]leucine incorporation into nonadapted NRK cells were found only at times up to 3 h; in contrast, the lead-adapted cells showed such increases only at longer times. The most pronounced differences between normal and lead-adapted cells were found with lead concentrations of 10 or 50 microM lead nitrate. Lead-adapted control cells incorporated 170% of the [3H]leucine taken up by nonadapted cells. In both adapted and nonadapted cells the pattern of synthesis of specific proteins showed varied and dose-dependent differences between the three cell sublines examined. The changed sensitivity of both DNA and protein synthesis following lead exposure appears to be a potent parameter in the development of resistance, perhaps through the development of specific lead-binding proteins.

Animals↗
PubMed2003

Prolonged habituation of the gill-withdrawal reflex in Aplysia depends on protein synthesis, protein phosphatase activity, and postsynaptic glutamate receptors.

Despite representing perhaps the simplest form of memory, habituation is not yet well understood mechanistically. We used a reduced preparation to analyze the neurobiological mechanisms of persistent habituation of a simple behavior, the defensive withdrawal reflex of the marine snail Aplysia californica. This preparation permits direct infusion of drugs into the abdominal ganglion during training via a cannula in the abdominal artery. Using siphon-elicited gill withdrawal, we demonstrate habituation of withdrawal that persists for 1-6 hr after repeated, spaced blocks of habituating stimulation. This form of habituation exhibits site specificity and requires protein synthesis because it is blocked by the presence of anisomycin, a protein synthesis inhibitor. We also find that habituation of gill withdrawal requires protein phosphatase activity, because it is blocked by okadaic acid, an inhibitor of protein phosphatase. Finally, habituation of gill withdrawal requires activation of NMDA-type and AMPA-type postsynaptic receptors within the abdominal ganglion, because it is blocked by infusion of dl-2-amino-5-phosphonovaleric acid or 6,7-dinitroquinoxaline-2,3-dione. The requirement for activation of postsynaptic glutamatergic receptors indicates that homosynaptic depression, an exclusively presynaptic mechanism that has been implicated previously in habituation in Aplysia, does not play a significant role in persistent habituation of the withdrawal reflex. Our results indicate that postsynaptic mechanisms, possibly including modulation of glutamate receptor function, play a major, heretofore unsuspected, role in habituation in Aplysia.

Animals↗
PubMed1983

Effect of human monocyte-released cytostatic factors on target cell DNA synthesis, protein synthesis, and ATP content.

Cultured human monocytes activated in vitro with lymphokines and lipopolysaccharide release cytostatic protein factors that may be separated by ion-exchange chromatography into two populations, termed cytostatic factors I and II (CF I and II). The effect of CF I and II on target cell DNA synthesis, protein synthesis, and ATP content and the possible presence of a CF-associated protease activity were investigated. Inhibition of DNA synthesis was detected 4 h after addition of either CF I or CF II, whereas inhibition of protein synthesis was first detected after 10-15 h. Moreover, 20 h after addition of either CF I or CF II the average DNA synthesis per cell was inhibited by 25-35%, as compared with 10-15% inhibition of protein synthesis. No significant alteration in cellular ATP content was observed in cells culture up to 25 h with either CF I or CF II. Thus, neither protein synthesis nor generation of ATP appeared to be primary targets of either CF I or CF II, but the factors may act more directly on DNA synthesis. Protease activity was not associated with either CF I or CF II, and the factors thus differed from a previously reported cytolytic protease released from activated murine macrophages.

Adenosine Triphosphate↗
PubMed2002

A platform for compartmentalized protein synthesis: protein translation and translocation in the ER.

Recent advances in the study of protein translocation across the membrane of the endoplasmic reticulum include insights into the mechanism of signal-sequence function. Biochemical and genetic studies have provided further evidence that lumenal proteins perform direct roles in secretory protein translocation and in the regulation of protein-conducting-channel permeability during membrane protein integration. A hypothesis identifying the endoplasmic reticulum as a site of mRNA localization and compartmentalized protein synthesis has been suggested.

Biological Transport, Active↗
PubMed1987

DNA synthesis, protein synthesis and platinum content following drug administration in cis-diamminedichloroplatinum(II) -sensitive and -resistant L1210 cells transferred from in vitro to in vivo conditions.

L1210 cells with in vitro induced drug resistance against cis-diamminedichloroplatinum(II) (cis-Pt(II] were inoculated in mice and several times transplanted. Then the effect of cis-Pt(II) on drug-sensitive and drug-resistant L1210 cells in mice was investigated. While the DNA and protein synthesis in drug-sensitive cells after in vivo cis-Pt(II) treatment was inhibited by 50%, that of drug-resistant cells remained virtually unaffected. The content of platinum in drug-sensitive cells was approximately three times higher in comparison with drug-resistant L1210 cells.

Animals↗
PubMed1996

Bacterioplankton Production Determined by DNA Synthesis, Protein Synthesis, and Frequency of Dividing Cells in Tuamotu Atoll Lagoons and Surrounding Ocean

This study compares three independent methods used for estimating bacterioplankton production in waters from the lagoon (mesotrophic) and the surrounding ocean (oligotrophic) of two atolls from the Tuamotu archipelago (French Polynesia).Thymidine and leucine incorporation were calibrated in dilution cultures and gave consistent results when the first was calibrated against cell multiplication and the second against protein synthesis. This study demonstrates that determining conversion factors strongly depends on the selected calculation method (modified derivative, integrative, and cumulative). These different estimates are reconciled when the very low proportion of active cells is accounted for.Frequency of dividing-divided cells (FDDC) calibrated using the same dilution cultures led to unrealistically high estimates of bacterial production. However, highly significant correlations between FDDC and either thymidine- or leucine-specific incorporation per cell were found in lagoon waters in situ. These correlations became more positive when oceanic data were added. This suggests that the FDDC method is also potentially valid to determine bacterioplankton growth rates after cross calibration with thymidine or leucine methods. If recommended precautions are observed, the three methods tested in the present study would give reliable production estimates.

Journal Article↗
PubMed1977

Water Stress and Protein Synthesis: V. Protein Synthesis, Protein Stability, and Membrane Permeability in a Drought-sensitive and a Drought-tolerant Moss.

The effects have been studied of water stress and desiccation on protein synthesis in the drought-tolerant moss Tortula ruralis and the drought-sensitive moss Hygrohypnum luridum. At any particular level of steady state water stress, the inhibition of protein synthesis was greater in H. luridum than in T. ruralis. Water stress-induced changes in the pattern of protein synthesis, as determined by the double label ratio technique, were minor in T. ruralis, but major in H. luridum. Proteins of both mosses were found to be stable during desiccation and subsequent rehydration. Changes in membrane permeability, as indicated by the leakage of amino acid, were observed during rehydration of desiccated moss and were dependent on the rate of desiccation. The leakage was small and reversible in T. ruralis but large and irreversible in H. luridum. Although H. luridum failed to recover from complete desiccation (80% loss in fresh weight), it was able to recover fully from steady state stress under conditions where a maximum loss of 55% in fresh weight was recorded.

Journal Article↗
PubMed1975

Reinitiation of deoxyribonucleic acid synthesis by deoxyribonucleic acid initiation mutants of Escherichia coli: role of ribonucleic acid synthesis, protein synthesis, and cell division.

The dnaA and dnaC genes are thought to code for two proteins required for the initiation of chromosomal deoxyribonucleic acid replication in Escherichia coli. When a strain carrying a mutation in either of these genes is shifted from a permissive to a restrictive temperature, chromosome replication ceases after a period of residual synthesis. When the strains are reincubated at the permissive temperature, replication again resumes after a short lag. This reinitiation does not require either protein synthesis (as measured by resistance to chloramphenicol) or ribonucleic acid synthesis (as measured by resistance to rifampin). Thus, if there is a requirement for the synthesis of a specific ribonucleic acid to initiate deoxyribonucleic acid replication, this ribonucleic acid can be synthesized prior to the time of initiation and is relatively stable. Furthermore, the synthesis of this hypothetical ribonucleic acid does not require either the dnaA of dnaC gene products. The buildup at the restrictive temperature of the potential to reinitiate deoxyribonucleic acid synthesis at the permissive temperature shows rather complex kinetics the buildup roughly parallels the rate of mass increase of the culture for at least the first mass doubling at the restrictive temperature. At later times there appears to be a gradual loss of initiation potential despite a continued increase in mass. Under optimal conditions the increase in initiation potential can equal, but not exceed, the increase in cell division at the restrictive temperature. These results are most easily interpreted according to models that postulate a relationship between the initiation of deoxyribonucleic acid synthesis and the processes leading to cell division.

Bacterial Proteins↗
PubMed1992

Liver cell volume and protein synthesis.

Protein synthesis in isolated rat hepatocytes was determined from the incorporation of [3H]leucine (4 mM) into acid-precipitable material in the presence of amino acids at twice their physiological concentration. Protein synthesis increased linearly with time and incubated cell protein, and was inhibited by cycloheximide by more than 95%. In normo-osmotic incubations containing amino acids at twice the physiological concentration the rate of [3H]leucine incorporation was 5.8 +/- 0.2 nmol/h per mg of cell protein (n = 26). Hyperosmotic cell shrinkage due to addition of 60 mM-NaCl or 120 mM-raffinose inhibited [3H]leucine incorporation into acid-precipitable material by 60 and 74% respectively, whereas hypo-osmotic cell swelling was ineffective. Inhibition of protein synthesis by adding 120 mM-raffinose was largely counteracted by simultaneous lowering of the NaCl concentration by 60 mM. Glutamine (10 mM) had no effect on protein synthesis in normo-osmotic incubations (320 mosM), but stimulated protein synthesis in hyperosmotically (440 mosM) pre-shrunken cells almost to rates found in normo-osmotic (320 mosM) control incubations. Cyclic AMP and vasopressin inhibited protein synthesis by 23% and 8% respectively, whereas insulin and phenylephrine were ineffective. However, inhibition of protein synthesis by cyclic AMP was about twice as strong in the presence of vasopressin or phenylephrine. When protein synthesis was preinhibited by cyclic AMP, [3H]leucine incorporation was stimulated by glutamine (10 mM), insulin or hypo-osmotic exposure. There was a close relationship between the inhibition of protein synthesis and the extent of hepatocyte shrinkage induced by the above-mentioned effectors, suggesting a role of cell volume in the regulation of hepatic protein synthesis.

Animals↗
PubMed1981

Partial purification of cytosolic proteins which control yeast mitochondrial protein synthesis.

Protein synthesis in isolated yeast mitochondria incubated in the presence of GTP is stimulated 2-fold by addition of dialyzed postpolysomal supernatant (S-150) at the start of the incubation. Incubation of the yeast S-150 with 5'-nucleotidase had no effect on the stimulatory activity suggesting that the increased protein synthesis does not result from guanine nucleotides. A partial purification of the protein factors which stimulate mitochondrial protein synthesis has been accomplished by chromatography on Sephacryl S-200. Stimulatory activity was eluted in two peaks, one in the 40,000 to 80,000 molecular weight range and a broad peak with a molecular weight of less than 10,000. Stimulation of mitochondrial protein synthesis by the low molecular weight activator fraction was proportional to the concentration of protein added and abolished by trypsin treatment suggesting that the low molecular weight activator is a protein(s). The rate of mitochondrial protein synthesis in the presence of activator, was linear for 40 min, while that in the presence of GTP was linear for only 20 min, suggesting that the activator and GTP stimulate protein synthesis by different mechanisms. Analysis of the products of the stimulated mitochondrial protein synthesis by gel electrophoresis revealed that the activator increased equally the labeling of all products. These results indicate that low molecular weight proteins present in the cytosol regulate mitochondrial protein synthesis.

Cytosol↗
PubMed1982

Effects of glucose, pyruvate, lactate, and amino acids on muscle protein synthesis.

Protein synthesis was measured in rat diaphragms incubated with serum amino acids + 0.35 mM L-[2,6-3H]tyrosine and different energy-yielding substrates. Muscles incubated with 5.5 mM glucose (with or without actinomycin D) synthesized more protein than those incubated with 11 mM pyruvate or 11 mM lactate. Tissue ATP decreased during incubation with lactate, but pyruvate maintained ATP, ADP, and creatine phosphate as well as glucose. Glucose 6-phosphate decreased in muscles incubated in glucose-free media. 14CO2 production from substrates was [1-14C]pyruvate greater than [1-14C]lactate greater than [3,4-14C]glucose. Intracellular lactate/pyruvate was measured to assess cytoplasmic free NADH/NAD+; the effect of different media on these ratios was lactate greater than glucose = lactate + pyruvate greater than pyruvate + glucose greater than pyruvate. Lactate + pyruvate (8.8 + 2.2 mM) supported protein synthesis better than pyruvate and as well as glucose. Adding glucose to pyruvate accelerated protein synthesis and increased NADH/NAD+. Iodoacetate (0.1 mM) inhibited glycolytic NAD reduction and abolished the stimulatory effect of glucose on protein synthesis in the presence of pyruvate. Supplementation of pyruvate media with 1 mM leucine or isoleucine stimulated protein synthesis, but beta-hydroxybutyrate, malate, alpha-ketoisocaproate, and all other amino acids were ineffective. The cytoplasmic redox potential may act as a translational modulator of protein synthesis in skeletal muscle.

Adenosine Triphosphate↗
PubMed2002

Activation of AMP-activated protein kinase leads to the phosphorylation of elongation factor 2 and an inhibition of protein synthesis.

Protein synthesis, in particular peptide-chain elongation, consumes cellular energy. Anoxia activates AMP-activated protein kinase (AMPK, see ), resulting in the inhibition of biosynthetic pathways to conserve ATP. In anoxic rat hepatocytes or in hepatocytes treated with 5-aminoimidazole-4-carboxamide (AICA) riboside, AMPK was activated and protein synthesis was inhibited. The inhibition of protein synthesis could not be explained by changes in the phosphorylation states of initiation factor 4E binding protein-1 (4E-BP1) or eukaryotic initiation factor 2alpha (eIF2alpha). However, the phosphorylation state of eukaryotic elongation factor 2 (eEF2) was increased in anoxic and AICA riboside-treated hepatocytes and in AICA riboside-treated CHO-K1 cells, and eEF2 phosphorylation is known to inhibit its activity. Incubation of CHO-K1 cells with increasing concentrations of 2-deoxyglucose suggested that the mammalian target of the rapamycin (mTOR) signaling pathway did not play a major role in controlling the level of eEF2 phosphorylation in response to mild ATP depletion. In HEK293 cells, transfection of a dominant-negative AMPK construct abolished the oligomycin-induced inhibition of protein synthesis and eEF2 phosphorylation. Lastly, eEF2 kinase, the kinase that phosphorylates eEF2, was activated in anoxic or AICA riboside-treated hepatocytes. Therefore, the activation of eEF2 kinase by AMPK, resulting in the phosphorylation and inactivation of eEF2, provides a novel mechanism for the inhibition of protein synthesis.

AMP-Activated Protein Kinases↗