Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hydroxyl groups of poly(ethyleneglycol) have been esterified (partly) with a number of carboxylic acids. When these esters are included in dextranpoly(ethyleneglycol)-water biphasic systems the partitions of proteins and membranes between the two phases (and the interface) are in some cases strongly affected. The affinity of serum albumin for the poly(ethyleneglycol)-rich phase is strongly increased when the fatty acid group consists of more than 10 carbon atoms. The partition also depends on the number of double bonds in the fatty acid. A corresponding relationship is found for membranes from spinach chloroplasts. The partitions of ovalbumin, lysozyme (EC 3.2.1.17) and ribonuclease (EC 3.1.4.22) are not influenced by the fatty acid esters. Esters of dibasic carboxylic acids show a minute but marked effect on the partition of proteins in general while malate and tartrate esters affect strongly the partition of chloroplast membranes. The partitions of both proteins and membranes are influenced by poly(ethyleneglycol) deoxycholate. Experiments with malate dehydrogenase (EC 1.1.1.37), lactate dehydrogenase (EC 1.1.1.27), fumarase (EC 4.2.1.2), enolase (EC 4.2.1.11) and glutamate-ocaloacetate transaminase (EC 2.6.1.1) show that their partitions, measured on enzymic activity basis, is changed when esters of benzoic, linolenic, tartaric or deoxycholic acid are included in the biphasic system. The mechanism behind the effect of the esterified poly (ethyleneglycol) on the partition of biomaterial, in this type of aqueous biphasic systems, is discussed in terms of a direct binding of the esters to the partitioned material.
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PMID:The effect of poly(ethyleneglycol) esters on the partition of proteins and fragmented membranes in aqueous biphasic systems. 99 68

1. RNAase (ribonuclease) U2, a purine-specific RNAase, was reduced, aminoethylated and hydrolysed with trypsin, chymotrypsin and thermolysin. On the basis of the analyses of the resulting peptides, the complete amino acid sequence of RNAase U2 was determined, 2. When the sequence was compared with the amino acid sequence of RNAase T1 (EC 3.1.4.8), the following regions were found to be similar in the two enzymes; Tyr-Pro-His-Gln-Tyr (38-42) in RNAase U2 and Tyr-Pro-His-Lys-Tyr (38-42) in RNAase T1, Glu-Phe-Pro-Leu-Val (61-65) in RNAase U2 and Glu-Trp-Pro-Ile-Leu (58-62) in RNAase T1, Asp-Arg-Val-Ile-Tyr-Gln (83-88) in RNAase U2 and Asp-Arg-Val-Phe-Asn (76-81) in RNAase T1 and Val-Thr-His-Thr-Gly-Ala (98-103) in RNAase U2 and Ile-Thr-His-Thr-Gly-Ala (90-95) in RNAase T1. All of the amino acid residues, histidine-40, glutamate-58, arginine-77 and histidine-92, which were found to play a crucial role in the biological activity of RNAase T1, were included in the regions cited here. 3. Detailed evidence for the amino acid sequence of the sequence of the proteins has been deposited as Supplementary Publication SUP 50041 (33 PAGES) AT THE British Library (Lending Division)(formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1975), 145, 5.
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PMID:The amino acid sequence of ribonuclease U2 from Ustilago sphaerogena. 115 64

The formation of a stable complex between glutamyl-tRNA synthetase and the first enzyme of chlorophyll biosynthesis glutamyl-tRNA reductase was investigated in the green alga Chlamydomonas reinhardtii. Apparently homogenous enzymes, purified after previously established purification protocols were incubated in various combinations with ATP, glutamate, tRNA(Glu) and NADPH and formed complexes were isolated via glycerol gradient centrifugation. Stable complexes were detected only after the preincubation of glutamyl-tRNA synthetase, glutamyl-tRNA reductase with either glutamyl-tRNA or free tRNA(Glu), ATP and glutamate, indicating the obligatory requirement of aminoacylated tRNA(Glu) for complex formation. The further addition of NADPH resulting in the reduction of the tRNA-bound glutamate to glutamate 1-semialdehyde led to the dissociation of the complex. Once complexed to the two enzymes tRNA(Glu) was found to be partially protected from ribonuclease digestion. Escherichia coli, Bacillus subtilis and Synechocystis 6803 tRNA(Glu) were efficiently incorporated into the protein-RNA complex. The detected complexes provide the chloroplast with a potential channeling mechanism for Glu-tRNA(Glu) into chlorophyll synthesis in order to compete with the chloroplastic protein synthesis machinery.
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PMID:Complex formation between glutamyl-tRNA synthetase and glutamyl-tRNA reductase during the tRNA-dependent synthesis of 5-aminolevulinic acid in Chlamydomonas reinhardtii. 145 6

The plasmid pTV1, constructed in Bacillus subtilis as a tool for insertional mutagenesis by the transposon Tn917, has been transferred to Bacillus amyloliquefaciens by transduction with the phage PBS1. Insertional mutants containing Tn917 were observed in the new host. Southern blot analysis of such mutants indicated no preference for insertion sites. The copy numbers of pTV1 in B. amyloliquefaciens and B. subtilis were found to be 1.4 and 14, respectively; the plasmid is less stable against loss in B. amyloliquefaciens. The overall transposition rate in B. amyloliquefaciens is nevertheless comparable to that in B. subtilis and large numbers of mutants are readily obtained. The yield of auxotrophs was about 0.7% of all mutants, but the preponderance of glutamate auxotrophs seen in B. subtilis was not observed. A number of auxotrophs were identified as to nutritional requirements and those tested were found to be stable. Mutants deficient in extracellular proteases, amylase, and ribonuclease (barnase) were also found and the inactivated barnase gene has been cloned in Escherichia coli. It seems likely, therefore, that any B. amyloliquefaciens gene for which there is a functional test could be cloned by this technique.
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PMID:Use of plasmid pTV1 in transposon mutagenesis and gene cloning in Bacillus amyloliquefaciens. 301 81

A cell-free extract of the anaerobic eubacterium, Clostridium thermoaceticum, catalyzes the synthesis of 5-aminolevulinic acid (ALA) from glutamate via the C5 pathway. The enzyme reaction resembles that of higher plants and algae in cofactor requirements and sensitivity to ribonuclease. From the phylogenetic distribution it is proposed that the C5 pathway evolved earlier than the ALA synthase pathway.
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PMID:5-Aminolevulinic acid formation from glutamate via the C5 pathway in Clostridium thermoaceticum. 334 79

Glutamine synthetase (GS) converts ammonia and glutamate into glutamine. We assessed the activity of the 5' regulatory region of the GS gene in developing transgenic mice carrying the chloramphenicol acetyltransferase (CAT) gene under the control of 3150 bp of the upstream sequence of the rat GS gene to obtain insight into the spatiotemporal regulation of its pattern of expression. To determine the organ-specific activity of the 5' regulatory region CAT and GS mRNA expression were compared by ribonuclease-protection and semi-quantitative in situ hybridization analyses. Three patterns were observed: the 5' region is active and involved in the regulation of GS expression throughout development (pericentral hepatocytes, intestines and epididymis); the 5' region shows no activity at any of the ages investigated (periportal hepatocytes and white adipose tissue); and the activity of the 5' region becomes repressed during development (stomach, muscle, brown adipose tissue, kidney, lung and testis). In the second group, an additional element must be responsible for the activation of GS expression. The last group included organs in which the 5' regulatory region is active, but not in the cells that express GS. In these organs, the activity of the 5' regulatory region must be repressed by other regulatory regions of the GS gene that are missing from the transgenic construct. These findings indicate that in addition to the 5' regulatory region, at least two unidentified elements are involved in the spatiotemporal pattern of expression of GS.
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PMID:Organ-specific activity of the 5' regulatory region of the glutamine synthetase gene in developing mice. 934 14

The N-methyl-D-aspartate (NMDA) subtype of glutamate receptors plays a key role in synaptic transmission, synaptic plasticity, synaptogenesis, and excitotoxicity in the mammalian central nervous system. The NMDA receptor channel is formed from two gene products from two glutamate receptor subunit families, termed NR1 and NR2. Although the subunit composition of native NMDA receptors is incompletely understood, electrophysiological studies using recombinant receptors suggest that functional NMDA receptors consist of heteromers containing combinations of NR1, which is essential for channel activity, and NR2, which modulates the properties of the channels. The lack of agonists or antagonists selective for a given subunit of NMDA receptors has made it difficult to understand the subunit expression, subunit composition, and posttranslational modification mechanisms of native NMDA receptors. Therefore, most studies on NMDA receptors that examine regional expression and ontogeny have been focused at the level of the mRNAs encoding the different subunits using northern blotting, ribonuclease protection, and in situ hybridization techniques. However, the data from these studies do not provide clear information about the resultant subunit protein. To directly examine the protein product of the NMDA receptor subunit genes, the development of subunit-specific antibodies using peptides and fusion proteins has provided a good approach for localizing, quantifying, and characterizing the receptor subunits in tissues and transfected cell lines, and to study the subunit composition and the functional effects of posttranslational processing of the NMDA subunits, particularly the phosphorylation profiles of NMDA glutamate receptors.
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PMID:Biochemical studies of the structure and function of the N-methyl-D-aspartate subtype of glutamate receptors. 1037 67

Regulation of extracellular excitotoxins by glial and neuronal glutamate transporters is critical to maintain synaptic terminal integrity. Factors interfering with the normal functioning of these transporters might be involved in neurodegeneration. Among them, recent studies have shown that hypoxia alters glutamate transporter function; however, it is unclear if hypoxia has an effect on the expression of glutamate transporters and which intracellular signaling pathways are involved. The C6 rat glial and GT1--7 mouse neuronal cell lines were exposed to hypoxic conditions (5% CO(2), 95% N(2)) and levels of glutamate transporter mRNA were determined by ribonuclease protection assay. After 21 hr, there was a 100% increase in levels of rat excitatory amino acid transporter 3 (EAAT3) mRNA in C6 cells and a 600% increase in levels of murine EAAT2 mRNA in GT1--7 cells. There was a similar increase in mRNA levels after hypoxia in C6 cells transfected with human EAAT2, whereas reoxygenation normalized the expression levels of glutamate transporters. Although the expression of EAATs was associated with increased immunoreactivity by Western blot, functioning of the transporters was decreased as evidenced by D-aspartate uptake. Finally, although the protein kinase C stimulator phorbol-12-myristate-13-acetate enhanced EAAT2 mRNA levels after hypoxia, protein kinase C inhibitor bisindolylmaleimide I had the opposite effect. Taken together, this study suggests that the hypoxia is capable of upregulating levels of EAATs via a protein kinase C-dependent compensatory mechanism. This increased expression is not sufficient to overcome the decreased functioning of the EAATs associated with decreased ATP production and mitochondrial dysfunction.
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PMID:Altered expression of glutamate transporters under hypoxic conditions in vitro. 1128 47

A naturally occurring mutation in the ectodomain of the TSH receptor (TSHr), K183R, has been described recently in a familial case of gestational hyperthyroidism. Hyperthyroidism was explained by the widening of the specificity of the mutant receptor toward human CG (hCG). In the present study, we attempted to understand in molecular terms the structure-phenotype relationships of this mutant in light of the available structural model of TSHr ectodomain established on the template of the atomic structure of the porcine ribonuclease inhibitor. To this aim, we studied by site-directed mutagenesis and functional assays in transfected COS cells the effects of substituting amino acids with different physicochemical properties for lysine 183. Unexpectedly, all TSHr mutants displayed widening of their specificity toward hCG. Molecular dynamics simulations suggested that the gain of function would be secondary to the release of a nearby glutamate residue (E157) from a salt bridge with K183. This hypothesis was supported by further site-directed mutagenesis experiments showing that the presence of an acidic residue in position 157, or in its vicinity, was required to observe the increase in sensitivity to hCG (an acidic residue in position 183 can partially fulfill the role of a free acidic residue in position 157 when tested on the background of a E157A mutant). Our results suggest also that additional natural mutations (especially K183M, N, or Q) in position 183 of TSHr are expected to be found in gestational hyperthyroidism.
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PMID:Lysine 183 and glutamic acid 157 of the TSH receptor: two interacting residues with a key role in determining specificity toward TSH and human CG. 1192 69

Increasing evidence based on pharmacological and genetic studies suggests that retinoid signaling plays an important role in developmental control of striatal neurons. In the present report, we screened for genes that might be regulated by retinoids in the developing striatum. We cultured tissue explants from the lateral ganglionic eminence (striatal primordium), and for regional comparison, its adjacent structures of the cerebral cortex and the medial ganglionic eminence in embryonic day 15 rat telencephalon. Using the ribonuclease protection assay, we found that both all-trans retinoic acid and 9-cis retinoic acid significantly up-regulated dopamine D1 receptor, heterotrimeric G protein olfactory, adenylyl cyclase type V and dopamine- and cyclic adenosine 3':5'-monophosphate-regulated phosphoprotein mRNAs in the lateral ganglionic eminence culture. By contrast, neither all-trans retinoic acid nor 9-cis retinoic acid significantly altered D1 receptor, heterotrimeric G protein olfactory, adenylyl cyclase type V and dopamine- and cyclic adenosine 3':5'-monophosphate-regulated phosphoprotein mRNAs in the cortical and the medial ganglionic eminence cultures except that D1 receptor mRNA was dramatically induced in the medial ganglionic eminence by retinoic acid treatments. To test whether the induction of multiple dopamine signaling molecules in the lateral ganglionic eminence was due to a general enhancement of neuronal differentiation by retinoic acid, we assayed the effects of retinoic acid on other differentiation markers, including glutamate decarboxylase 65, NR1 subunit of glutamate NMDA receptor and microtubule-associated protein-2. None of these genes were significantly altered by retinoic acid treatments in the lateral ganglionic eminence culture, indicating the specificity of gene regulation by retinoic acid signaling. As D1 receptor, heterotrimeric G protein olfactory, adenylyl cyclase type V and dopamine- and cyclic adenosine 3':5'-monophosphate-regulated phosphoprotein are important molecules involved in propagation of striatal dopamine neurotransmission, our study raises the hypothesis that retinoid signaling may coordinately activate the transcriptional program that is associated with the dopamine signaling pathway in developing striatal neurons. Such coordinate regulation by retinoids may be part of the mechanisms by which the complex yet highly organized neurochemical constituents of the striatum are established during development.
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PMID:Regulation of multiple dopamine signal transduction molecules by retinoids in the developing striatum. 1593 42


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