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

To investigate a possible direct action of glucocorticoids on adrenal steroidogenesis, the effect of corticosterone on the conversion of pregnenolone into various metabolites by frog adrenal tissue was examined. Frog interrenal slices were incubated with [3H]pregnenolone (1 mCi/ml) and the various labelled metabolites analysed by reverse-phase high-performance liquid chromatography. With the methanol gradient used, five identified steroids were resolved: progesterone, 11-deoxycorticosterone, corticosterone, 18-hydroxycorticosterone and aldosterone. Corticosterone (10 micrograms/ml) induced a 45-80% decrease in all steroids synthesized from [3H]pregnenolone. In contrast, the glucocorticoid agonist dexamethasone did not reduce the rate of conversion of pregnenolone into its metabolites. In addition, the inhibitory effect of corticosterone was not reversed by the specific glucocorticoid antagonist RU 43044. These results show that corticosterone exerts a direct inhibitory effect on adrenal steroid secretion. In addition, our data indicate that the ultra-short regulation induced by corticosterone is not mediated through glucocorticoid receptors.
J Mol Endocrinol 1991 Jun
PMID:Self-inhibition of steroid secretion by amphibian adrenocortical cells is not mediated through glucocorticoid receptors. 188 87

The highly purified preparations of Bollum's terminal transferase from calf thymus were shown to catalyze, along with the common reaction of nucleotide addition to the 3'-terminus of an oligonucleotide primer, a "non-common" reaction between dNTP or rNTP on one hand, and various alcohols on the other hand. This reaction was carried out with ethylene glycol, glycerol, ethanol and methanol to produce substances containing one molecule of nucleotide, one molecule of alcohol and non-organic pyrophosphate. The reaction conditions are cacodylate buffer, pH 7, 2, in the presence of Mg2+ or Co2+ ions. The structure was determined for the product of the reaction between glycerol and dATP, which appeared to be 2,3-dihydroxypropyl-ether of 2'-deoxyadenosine-5'-monophosphate.
Mol Biol (Mosk)
PMID:[A new reaction catalyzed by Bollum's terminal deoxyribonucleotidyltransferase]. 189 36

The oxidation of methane to methanol in methanotrophic bacteria is catalysed by the enzyme methane monooxygenase (MM0). This multicomponent enzyme catalyses a range of oxidations including that of aliphatic and aromatic compounds and therefore has potential for commercial exploitation. This study details the molecular characterization of the soluble MMO (sMMO) genes from the Type II methanotroph Methylosinus trichosporium OB3b. The structural genes encoding the alpha, beta and gamma subunits of sMMO protein A and the structural gene encoding component B have been isolated and sequenced. These genes have been expressed and their products identified using an in vitro system. A comparative analysis of sMMO predicted sequences of M. trichosporium OB3b and the taxonomically related M. capsulatus (Bath) is also presented.
Mol Microbiol 1991 Feb
PMID:Molecular analysis of the methane monooxygenase (MMO) gene cluster of Methylosinus trichosporium OB3b. 190 25

When Eubacterium sp. 144 was grown in the presence of progesterone, extracts of these cells contained a 4-ene-3-ketosteroid-5 alpha-reductase (5 alpha-reductase). No evidence for the presence of a 5 beta-steroid-reductase or a 5 alpha to 5 beta-steroid-isomerase was found. 5 alpha-Reductase activity was dependent on reduced methyl viologen as the electron donor and this could be generated biologically by adding pyruvate or H2 to cell extracts or chemically by adding sodium dithionite. NADH or NADPH with or without flavin nucleotides were not electron donors for 5 alpha-reductase. Most of the 5 alpha-reductase activity (60-65%) of crude extracts was located in the membrane fraction and the enzyme was solubilized by treatment with 1% Triton X-100. Optimum 5 alpha-reductase activity occurred at pH 7.0-7.5 in potassium phosphate buffer but was stimulated by Tris-HCl buffer (pH 8.0-9.0). 5 alpha-Reductase activity was highest at 10% (v/v) methanol and was progressively inhibited by higher methanol concentrations. Sulfhydryl reagents strongly inhibited 5 alpha-reductase but the enzyme was not affected by other metabolic inhibitors. Extracts prepared from cells induced with 16-dehydroprogesterone and grown without hemin contained 5 alpha-reductase and 16-dehydroprogesterone-reductase activities equivalent to those found in extracts of induced cells grown with hemin. This indicates that hemin is not required for the synthesis of active steroid double bond-reductases in strain 144.
J Steroid Biochem Mol Biol 1991 Sep
PMID:Properties of a 4-ene-3-ketosteroid-5 alpha-reductase in cell extracts of the intestinal anaerobe, Eubacterium sp. strain 144. 191 27

A Triticum durum cDNA library prepared from developing endosperm (22 days after flowering (DAF] was screened using synthetic oligonucleotide probes covering part of the CM3 and CM16 N-terminal protein sequences. A full-length cDNA clone (pTd78) encoding the CM16 protein (chloroform/methanol-soluble protein) was isolated and characterized. To our knowledge this is the first characterization of a clone coding for a wheat CM protein. The CM16 protein is synthesized as a preprotein with a signal peptide of 24 residues, the molecular weight of the mature protein being 13,438 Da. As other members of the cereal trypsin/alpha-amylase inhibitor family, the CM16 protein contains 10 cysteine residues, their position being well conserved. In developing endosperm the highest level of CM16 mRNA was detected at mid-maturation.
Plant Mol Biol 1990 Mar
PMID:Cloning and characterization of a cDNA encoding the wheat (Triticum durum Desf.) CM16 protein. 210 17

Expression of the gene of the methanol-soluble, heat-stable enterotoxin of Escherichia coli (STA) allowed the identification by SDS-PAGE of a cell-associated 7500 Dalton STA-related peptide; when similar experiments were performed with a phosphate buffer SDS-PAGE system, an additional Mr 9800 band became apparent. The 9800 Dalton form, pre-pro-STA, accumulated as an intracellular species when the experiments were performed in the presence of the proton ionophore CCCP (carbonylcyanide m-chlorophenylhydrazone); by pulse-chase experiments, it was shown that pre-pro-STA became a periplasmic Mr 7500 pro-STA and this form was chased to the culture supernatant; periplasmic and extracellular pro-STA showed the same electrophoretic mobility. A short time after the pulse, pro-STA was converted extracellularly to mature STA (Mr 4500). It is proposed that STA is synthesized as pre-pro-STA, a 72-amino-acid peptide that is subsequently cleaved between amino acids 19 and 20 as it is translocated across the inner membrane. The resulting 53-amino-acid pro-STA is first detected in the periplasm and is then secreted to the culture supernatant. Pro-STA is cleaved extracellularly to yield mature STA (Mr 4500).
Mol Microbiol 1990 Feb
PMID:Two precursors of the heat-stable enterotoxin of Escherichia coli: evidence of extracellular processing. 218 46

The present study was undertaken to isolate and identify various lipids bound to 14C label during hepatic microsomal metabolism of 14CCl4 in vitro under anaerobic conditions and in vivo in rats. The two major radioactive fractions identified by thin-layer chromatography each for neutral lipids and phospholipids from in vitro and in vivo experiments corresponded to fatty acids and triglycerides and to phosphatidylcholine (PC) and phosphatidylethanolamine (PE), respectively. Approximately 89% of the radioactivity associated with phospholipids was found in PC and PE fractions. Hydrolysis of PC and PE with phospholipase A2 (EC 3.1.1.4) released about 50% of the total radioactivity as lipid moieties corresponding to fatty acids. The radioactive neutral lipids and the lipid moieties hydrolyzed from PC and PE were methylated with boron trifluoride in methanol. These methylated lipids were separated by reversed-phase high-performance liquid chromatography (HPLC), and the elution profiles of 14C label found for the lipids obtained from in vitro experiments were similar to those from in vivo. The major radioactive fractions eluted immediately after methyl oleate were identified as trichloromethyloctadecenoic and trichloromethyleicosatrienoic acid methyl esters by chemical ionization mass spectrometry. The mass spectral analysis of these fractions also indicated the formation of dichlorocarbene adduct of oleic acid. However, similar mass spectrometric detection of trichloromethylated lipids was not evident in neutral lipids and phospholipids isolated from in vivo studies. The 14C-labeled lipids eluted as a nonpolar fraction exhibited a high molecular weight containing more than three chlorines. Dimerization and cross-linking of trichloromethylated lipids based on HPLC and mass spectral analysis are also discussed in this paper.
Mol Toxicol
PMID:Covalent modification of hepatic microsomal lipids of rats by carbon tetrachloride. 248 57

Calcium ion recognition by a dicarboxylic ionophore containing two (S)-phenylalanine residues joined via an amide bond by a flexible tri-oxa-undecanoyl bridge (Phe-3-O) has been investigated in a wide pH range (from pH 2 to 12). Experiments were performed in methanol and chloroform by 1H and 13C NMR, relaxation times and 2D NMR (COSY, NOESY and J-resolved experiments). Recognition is shown to be regulated by pH, as it occurs in at least three different coordination modes according to the experimental conditions. Even at low pH (pH 2) the ion is already complexed in the compartment created by the ethereal oxygens and the amide carbonyls. At higher pH, it becomes fully encapsulated in a pseudo-cyclic structure and at very basic pH it is localized between the amide carbonyls and the carboxylates. For these peculiar properties Phe-3-O appears to be a very promising ionophore in a trans-membrane pH gradient system.
J Mol Recognit 1989 Sep
PMID:pH regulation of calcium recognition by an amino acid containing acyclic ionophore. 263 99

The uptake of [3H]choline was investigated using isolated perfused rat lungs and primary cultures of granular pneumocytes isolated by tryptic digestion of rat lungs. Metabolic products were separated from free choline by chloroform:methanol extraction and column chromatography. Tissue-associated [3H]choline increased progressively in the perfused lung, and estimated mean intracellular concentration at 2 h was 12 times the extracellular concentration (5 microM). Choline uptake was inhibited by ventilation with CO and by perfusion with the choline analog, hemicholinium-3 (HC-3). Isolated granular pneumocytes also accumulated choline against a concentration gradient by an energy-dependent process. The concentration for half-maximal uptake, after correction for the diffusion component, was estimated at 18 +/- 4 microM (mean +/- SE; n = 3), and the estimated maximal rate of uptake was 213 +/- 44 pmol/min/microliter cell water. HC-3 inhibited uptake by approximately 50% at a concentration of 10(-4) M. There was no effect on uptake when Na+ in the medium was replaced by Li+ or N-methylglucamine+. These results indicate that granular pneumocytes possess a transport system that results in accumulation of choline against a concentration gradient. The characteristics of uptake indicate that this system is similar to the low affinity choline transport system of other organs.
Am J Respir Cell Mol Biol 1989 Dec
PMID:Choline transport by lung epithelium. 263 57

In Pichia pastoris, alcohol oxidase (AOX) is the first enzyme in the methanol utilization pathway and is encoded by two genes, AOX1 and AOX2. The DNA and predicted amino acid sequences of the protein-coding portions of the genes are closely homologous, whereas flanking sequences share no homology. The functional roles of AOX1 and AOX2 in the metabolism of methanol were examined. Studies of strains with disrupted AOX genes revealed that AOX1 was the major source of methanol-oxidizing activity in methanol-grown P. pastoris. The results of two types of experiments each suggested that the difference in AOX activity contributed by the two genes was a consequence of sequences located 5' of the protein-coding portions of the genes. First, the coding portion of AOX2 was able to functionally substitute for that of AOX1 when placed under the control of AOX1 regulatory sequences. Second, when labeled oligonucleotide probes specific for the 5' nontranslated region of each gene were used, it was apparent that the steady-state level of AOX1 mRNA was much higher than that of AOX2. Except for the difference in the amount of mRNA present, the two genes appeared to be regulated in the same manner. A physiological reason for the existence of AOX2 was sought but was not apparent.
Mol Cell Biol 1989 Mar
PMID:Functional characterization of the two alcohol oxidase genes from the yeast Pichia pastoris. 265 90


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