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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteins present in messenger ribonucleoprotein particles were labeled with [35S]-methionine in Ehrlich ascites tumor cells in which synthesis of new ribosomes was inhibited. Poly(A)-protein complexes were isolated from free and membrane-bound polyribosomes by sucrose gradient centrifugation and affinity chromatography on oligo(dT)-cellulose. Both classes of Poly(A)-protein particles contain a poly(A) chain of about 70 adenyl residues and a protein with a molecular weight of 76000 attached to it.
Mol Biol Rep 1976 Sep
PMID:Characterization of poly(A)-protein complexes isolated from free and membrane-bound polyribosomes of Ehrlich ascites tumor cells. 103 5

A ribonucleoprotein was released from carefully purified rat liver mitochondrial polyribosomes after dissociation with 1 M potassium chloridepuromycin. This ribonucleoprotein was characterized by a sedimentation coefficient ranging from 10-14 S and buoyant density of 1.48 g cm(-3) in cesium chloride equilibrium centrifugation differing in these parameters from the subunits of mitochondrial ribosomes. Poly(A)-containing RNA constituted more than 30% of the total RNA content in this non-ribosomal ribonucleoprotein.
Mol Biol Rep 1975 Jul
PMID:Messenger RNA-containing ribonucleoprotein from mitochondrial polyribosomes of rat liver. 116 Aug 79

Kinetics of incorporation of (3H) uridine into cytoplasmic RNA fractions of rat liver is investigated. The fractions include free and membrane bound polysomes, rough membranes sedimenting with mitochondria and free cytoplasmic RNA particles. (1) Poly(A) containing RNA, isolated by oligo-dT cellulose, amounts to 0.4% of the total RNA in the homogenate, 0.5% in bound polysomes, 3.4% in free polysomes and 16% in free cytoplasmic RNA particles. (2) The rate of (3H) uridine incorporation into RNA lacking poly(A) proceeds uniformly in all subcellular fractions except for free cytoplasmic RNA particles, which accumulate negligible amounts of radioactivity. (3) The initial labelling of RNA containing poly(A) is most active in free cytoplasmic RNA particles supporting their identity as mRNA en route to polysomes. The initial specific radioactivities decrease in the following order: homogenate, bound polysomes, rough membranes sedimenting with mitochondria, free polysomes. The data suggest that mRNA is supplied to free and membrane-bound polysomes via different routes. The kinetic analysis indicates that free cytoplasmic RNA particles may be a precursor of mRNA of free polysomes rather than that of bound polysomes. (4) The kinetic differences of free and membrane bound polysomes are also demonstrated by comparing the radioactivity of RNA containing poly(A) to the total radioactivity at various incorporation times. In bound polysomes this decreases from 31% at 1 h to 10% at 25 h, whereas in free polysomes the corresponding ratio increases from 10 to 13%. RNA containing poly(A) of free cytoplasmic RNA particles represents 64% of the total radioactivity throughout the experiment.
Mol Cell Biochem 1975 Aug 30
PMID:Labelling kinetics of RNA containg poly(A) in liver subcellular fractions. 116 64

A method is proposed for analysis of natural and chemically modified polynucleotides which consists in enzymatic conversion of the polymer or oligomer into nucleosides followed by cation-exchange chromotography on the microcolumns. By using the method developed it was shown that after treatment of the yeast tRNAVal and tRNAPhe with monoperphthalic acid N-oxides of adenosine and cytidine were formed. Poly (U, G) was not modified at a measurable extent whereas GMP was decomposed. In tRNAVal (yeast)the adenosines and cytosines of the anticodon loop and 3'-end are most reactive; it is the case for the C17 of the diHU-loop as well. These data are in agreement with the results obtained for tRNA modification with other reagents and for limited enzymatic hydrolysis of the tRNAVal. The limitations of the reaction of the monoperphthalate with nucleic acids are briefly discussed.
Mol Biol (Mosk)
PMID:[Modification of tRNA 1 Val from yeast with monoperphthalic acid]. 121 65

The ratio of mRNA not selected for polyadenylation (non-poly(A)+ selected) to mRNA selected for polyadenylation (poly(A)+) for the beta 1, alpha 1 and gamma 2 subunits of the GABAA receptor complex was examined in rats as a function of age. RNA was extracted from whole brain of rats that were either 0, 1, 3, 5 or over 60 days of postnatal age. Poly(A)+ mRNA was purified by oligo(dT)-cellulose chromatography. Non-poly(A)+ selected mRNA and poly(A)+ mRNA for the GABAA receptor beta 1, alpha 1 and gamma 2 subunits were examined by Northern blot analysis using cDNA probes specific for these subunits. Levels of GABAA receptor beta 1 subunit mRNA were also examined by solution hybridization analysis with a beta 1 riboprobe. Analysis of Northern blots revealed that levels of poly(A)+ beta 1 subunit mRNA were highest at 0 days of age, but decreased and reached adult levels by 5 days of postnatal age. However, levels of the beta 1 subunit message extracted from non-poly(A)+ selected mRNA were not significantly different at any of the ages examined, suggesting the existence of a population of beta 1 subunit mRNA that is not polyadenylated. The age-related discrepancy between beta 1 subunit levels measured in non-poly(A)+ selected mRNA and poly(A)+ mRNA was also observed using solution hybridization analysis. In contrast, levels of both non-poly(A)+ selected mRNA and poly(A)+ mRNA for the alpha 1 subunit of the GABAA complex increased from 0 days of age to adulthood. Similarly, levels of both non-poly(A)+ selected mRNA and poly(A)+ mRNA for the GABAA receptor gamma 2 subunit increased with age.(ABSTRACT TRUNCATED AT 250 WORDS)
Brain Res Mol Brain Res 1992 Jul
PMID:Developmental profile of polyadenylated and non-polyadenylated GABAA receptor subunit mRNAs. 127 41

Expression of growth hormone (GH) gene during early stages of larval development of the teleost Sparus aurata was determined by Northern blot analysis. Poly(A+) RNA was prepared from a pool of larvae collected on different days after hatching. When hybridized to Sparus aurata GH cDNA, GH specific mRNA was first seen on day 6 post-hatching. In contrast, the levels of beta-actin mRNA, which was used to normalize for RNA amounts, were already high on the day of hatching. Our results suggest that expression of the GH gene is very low immediately after hatching, and increases dramatically within 6 days.
Mol Cell Endocrinol 1992 Sep
PMID:Developmental expression of the growth hormone gene in the gilthead sea bream Sparus aurata. 135 82

Poly(A)+ mRNAs from the cerebral cortex of aged (24 months) and young adult (3 months) rats were isolated and injected into Xenopus oocytes to express functional neurotransmitter receptors and voltage-operated channels. Electrophysiological recordings of induced membrane currents were used as a measure of the relative amounts of mRNA encoding different receptors and channels, and to study their functional properties. There were no large differences apparent between mRNAs from aged and adult rats, in marked contrast to the dramatic (1000-fold) changes in mRNA expression that occur during embryonic and postnatal development. The membrane currents induced by glutamate or acetylcholine (ACh) application were roughly one third smaller in oocytes injected with mRNA from aged cerebral cortex than in oocytes injected with mRNA from adult cerebral cortex, whereas currents induced by gamma-aminobutyric acid (GABA), kainate or serotonin (5-HT) application, and by activation of voltage-operated Na+ and Ca2+ channels were not significantly different. We did not observe any age-related differences in the properties of the receptors and channels studied.
Brain Res Mol Brain Res 1992 Mar
PMID:Messenger RNAs coding for receptors and channels in the cerebral cortex of adult and aged rats. 137 2

Poly(A)+ RNA from rat cerebral cortex expresses gamma-aminobutyric acid (GABA)-activated membrane current responses in Xenopus oocytes, mediated by GABAA receptors (IG-Actx). In contrast, RNA from bovine retina expresses GABA responses composed of two pharmacologically distinct Cl- currents, one mediated by GABAA receptors (IG-Aret) and the other by atypical GABA receptors that are resistant to bicuculline and are not activated by baclofen (IG-BR). The pharmacology of the bicuculline/baclofen-insensitive GABA receptors was further investigated by comparing actions of hexachlorocyclohexane (HCH) enantiomers on GABA-activated membrane currents expressed in oocytes by brain and retina RNA. gamma-HCH (lindane) was a potent inhibitor of IG-Actx, with suppression of currents detectable at concentrations as low as 50 nM. The IC50 for gamma-HCH, calculated from inhibitory effects on maximum IG-Actx (current elicited by 3 mM GABA), was 7.3 +/- 3 microM. Inhibitory effects of gamma-HCH on IG-Aret were qualitatively similar to those described for IG-Actx. In contrast, alpha-HCH and delta-HCH induced clear positive modulation of IG-Actx elicited by low (e.g., 10 microM) concentrations of GABA. Thresholds for the modulatory effects of alpha-HCH and delta-HCH were between 100 and 300 nM, with maximum levels of potentiation (5-7-fold) between 20-50 microM. Potentiation of IG-Actx by alpha- and delta-HCH was reversible and largely insensitive to the benzodiazepine antagonist flumazenil (1 microM). Assays on maximum IG-Actx indicated that alpha-HCH (10-100 microM) caused only marginal reductions in response (less than or equal to 15%), whereas delta-HCH had stronger inhibitory effects (IC50, 20-30 microM). At concentrations between 0.1 and 50 microM, beta-HCH induced only 10-25% facilitation of IG-Actx elicited by 10 microM GABA and had no clear effects on maximum responses. IG-BR was also potently inhibited by gamma-HCH. Thresholds for detecting reductions in current were approximately 20 nM, and the IC50 calculated from effects on maximum responses was 5.8 +/- 2 microM. However, neither alpha-HCH nor delta-HCH (1-100 microM) induced any potentiation of IG-BR. alpha-HCH had some weak inhibitory effects that were largely surmountable, whereas delta-HCH and beta-HCH were essentially inactive. These experiments raise the possibility that alpha- and delta-HCH constitute a novel class of GABAA receptor modulators, which might prove to be useful for investigating the mechanisms underlying regulation of GABAA receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Pharmacol 1992 Jun
PMID:Effects of hexachlorocyclohexanes on gamma-aminobutyric acid receptors expressed in Xenopus oocytes by RNA from mammalian brain and retina. 137 27

We report the isolation of a ripening-related apple cDNA which is complementary to a mRNA which may be involved in ethylene production. Poly(A)+ RNA was extracted from cortical tissue of ripe apple fruit (Malus domestica Borkh cv. Golden Delicious) and a cDNA library constructed in the plasmid vector pSPORT. The library was screened with pTOM13, a tomato cDNA clone thought to code for ACC oxidase in that fruit. An apple cDNA clone (pAP4) was isolated and sequenced. The 1182 bp cDNA insert includes an open reading frame of 942 bp, and shows strong homology with reported tomato and avocado sequences, both at the nucleic acid and amino acid levels. The polypeptide has a calculated molecular mass of 35.4 kDa and a calculated pI of 5.15. In apple cortical tissue, expression of pAP4-complementary RNA increased with ethylene production by the fruit during ripening. Expression was also enhanced in both ethylene-treated and wounded fruit.
Plant Mol Biol 1992 May
PMID:An ethylene-related cDNA from ripening apples. 137 61

Poly(A)+ RNA from bovine retina expressed gamma-aminobutyric acid (GABA)-activated membrane current responses in Xenopus oocytes, consisting of two pharmacologically distinct components. One component (IG-Aret) was mediated by GABAA receptors, and the other component (KG-BR) by atypical GABA receptors that were resistant to inhibition by bicuculline and insensitive to activation by baclofen. To further characterize the bicuculline/baclofen-insensitive GABA receptors, electrical recordings were made measuring the sensitivity of IG-BR to two Cl- channel inhibitors, t-butylbicyclophosphorothionate (TBPS) and picrotoxin. For purposes of comparison, effects of TBPS and picrotoxin were also assayed on currents mediated by GABAA receptors expressed in oocytes by rat cerebral cortex RNA (IG-Actx). The main finding of this study was that TBPS was a surprisingly weak inhibitor of IG-BR, whereas IG-Actx was potently suppressed. Assays on maximum responses indicated that IG-Actx was at least 500 times more sensitive to TBPS than was IG-BR (IC50 values of approximately 0.2 microM and greater than 50 microM, respectively). Moreover, inhibition of IG-Actx by micromolar concentrations of TBPS was largely insurmountable, whereas the weak inhibitory effects on IG-BR showed strong dependence on agonist concentration. For example, 10 microM TBPS reduced maximum IG-Actx by greater than 90%, an effect that was not significantly reversed by 10-fold increases in the concentration of agonist. In contrast, the same concentration of TBPS caused a 2-fold increase in the EC50 for IG-BR but had only marginal (less than 5%) inhibitory effects on maximum responses. Picrotoxin inhibited both types of current, but assays on maximum responses indicated that IG-Actx was approximately 30 times more sensitive than IG-BR (IC50 values of approximately 1 and 30 microM, respectively). Inhibitory effects of picrotoxin on IG-BR again showed strong dependence on agonist concentration, but in this case there was also a clear insurmountable component. Comparisons between IG-Actx and IG-Aret suggested that GABAA receptors expressed by either brain or retina RNA showed approximately the same sensitivity to TBPS and picrotoxin. Our experiments indicate that the bicuculline/baclofen-insensitive GABA receptors expressed by retina RNA differ markedly from GABAA receptors in their sensitivity to TBPS and picrotoxin. Defining the structural features responsible for these differences at the molecular level will provide a further means of investigating the complex mechanisms underlying interactions between inhibitors and GABA-activated Cl- channels.
Mol Pharmacol 1992 Jul
PMID:Characterization of bicuculline/baclofen-insensitive gamma-aminobutyric acid receptors expressed in Xenopus oocytes. I. Effects of Cl- channel inhibitors. 137 24


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