Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An acid ribonuclease (optimum pH 6.0) has been purified from bovine brain in a five-step procedure. The preparation appeared homogeneous on SDS-polyacrylamide gel electrophoresis. The molecular size of the acid ribonuclease is 70 kDa and it is a dimeric protein with a subunit molecular size of 35 kDa. The acid RNase was activated by aluminum at low concentration. Preincubation of the acid RNase with 10 microM increased the specific activity of the enzyme 2.3-fold at acid pH, while the effect of aluminum was much weaker at alkaline pH under otherwise the same conditions. A stoichiometry of 1: 1 for the binding aluminum to brain acid RNase was estimated. None of the enzyme-bound aluminum was dissociated by dialysis against 50 mM HEPES, pH 7.0 at 4 degrees C for 24 h. Citrate, EDTA, NaF, and apotransferrin abolished the effects of aluminum on the enzyme. Ribonucleic acid also protected the enzyme against the activation caused by aluminum. These results suggest that accumulation of aluminum in brain may change the regulation of ribonucleic acid metabolism.
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PMID:Activation of acid ribonuclease from bovine brain by aluminum. 178 12

With the previously obtained rat liver serine dehydratase cDNA (SDH2; Ogawa, H., Miller, D.A., Dunn, T., Su, Y., Burcham, J. M., Peraino, C., Fujioka M., Babcock, K., and Pitot, H. C. (1988) Proc. Natl. Acad. Sci. U.S. A. 85, 5809-5813) as a probe, we isolated a different species of cDNA (SDH3) from the same cDNA library from which SDH2 was obtained. Nucleotide sequence analysis has indicated that SDH3 has an open reading frame which encodes 327 amino acid residues and which is identical to that of the cDNA obtained by Noda et al. (Noda, C., Ito, K., Nakamura, T., and Ichihara, A., (1988) FEBS Lett. 234, 331-335). Primer extension analysis and RNase protection mapping clarified that the SDH3 mRNA was the major mRNA for serine dehydratase in the liver, and its transcription begins with a T residue located 23 nucleotides down-stream of a TATA-like box. In vitro transcription/translation experiment demonstrated that SDH3 encoded a polypeptide of 35 kDa, a size in agreement with that of the subunit of the purified protein, whereas SDH2, despite having a size larger than SDH3, produced a peptide of much smaller size that reacted with anti-serine dehydratase IgG. SDH2 was found to have a stop codon early in the sequence and is predicted to encode a polypeptide of 8.9 kDa. Also, SDH2 has a 5'-noncoding sequence different from that of SDH3. These results indicate that alternative transcription initiation and different modes of splicing of the primary transcripts of rat serine dehydratase gene result in the formation of two species of mRNA, of which only one is translated into the mature serine dehydratase protein.
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PMID:Rat serine dehydratase gene codes for two species of mRNA of which only one is translated into serine dehydratase. 238 60

Human Wilms' tumor (WT) expresses insulin-like growth factor (IGF) II and its cognate receptor, type 1 IGF receptor, forming a self-stimulating "autocrine loop." The biological activity of IGF-II is modulated by a class of soluble receptors called IGF binding proteins (IGFBP). To determine if IGFBP play a role in the biology of WT, extracts of nude mouse heterotransplants of three blastemal WT were examined for the ability to bind radiolabeled IGF-II by ligand blot analysis. [125I]IGF-II bound to a protein of M(r) 35 kDa. To confirm that this binding protein was being expressed by the tumor itself and not background from the host, tumor explants were prepared in cell culture. Conditioned culture media from blastemal WT cell cultures were found to contain the 35-kDa IGFBP. This secreted binding protein was identified as IGFBP-2 by screening for reactivity to characterized IGFBP antisera. Total RNA from primary WT or WT cells in culture was examined for expression of IGFBP-2 mRNA using an RNase protection assay. All three WT expressed IGFBP-2 mRNA. These data suggest a role for IGFBP-2 in the IGF-II-dependent growth of Wilms' tumor and in the developing kidney.
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PMID:Expression of insulin-like growth factor binding protein 2 (IGFBP-2) in Wilms' tumors. 752 57

We evaluated two independent models of eosinophil differentiation for their ability to synthesize the ribonuclease toxins eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP). Cells from the clone 15 subline of HL-60 (human promyelocytic leukemia) produced both EDN and ECP; production of EDN increased in response to butyric acid (BA). CD34+ peripheral blood progenitor cells (PBPCs) grown with cytokines promoting eosinophil differentiation also produced EDN. EDN from both the clone 15 and PBPCs was more heterogeneous and heavily glycosylated (approximately 22-45 kDa) than EDN from the mature peripheral blood eosinophils (18-25 kDa). The heterogeneity of EDN from the clone 15 cells was not altered by endoglycosidase Hf, whereas treatment with peptide-N-glycosidase F (PNGase F) produced a single-band immunoreactive band (approximately 15 kDa). In contrast, only the highest molecular weight forms of EDN from differentiated PBPCs were eliminated by PNTGase F (reduced to 22-35 kDa), suggesting the presence of uncharacteristic forms of posttranslational modification. Synthesis of hyperglycosylated proteins has not been previously reported in PBPCs and is a feature shared with tumor cells and cell lines.
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PMID:Hyperglycosylation of eosinophil ribonucleases in a promyelocytic leukemia cell line and in differentiated peripheral blood progenitor cells. 761 5

We cloned the Saccharomyces cerevisiae homologue of mammalian RNase HI, which itself is related to the prokaryotic RNase HII, an enzyme of unknown function and previously described as having minor activity in Escherichia coli. Expression of the corresponding yeast 35 kDa protein (named by us RNase H(35)) in E. coli and immunological analysis proves a close evolutionary relationship to mammalian RNase HI. Deletion of the gene (called RNH35) from the yeast genome leads to an about 75% decrease of RNase H activity in preparations from the mutated, still viable cells. Sequence comparison discriminates this new yeast RNase H from earlier described yeast enzymes, RNase H(70) and RNase HI.
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PMID:Yeast RNase H(35) is the counterpart of the mammalian RNase HI, and is evolutionarily related to prokaryotic RNase HII. 946 32

In plants, the pollen coat covers the exine wall of the pollen and is the outermost layer that makes the initial contact with the stigma surface during sexual reproduction. Little is known about the constituents of the pollen coat, especially in wind-pollinated species. The pollen coat was extracted with diethyl ether from the pollen of maize (Zea mays L.), and a predominant protein of 35 kDa was identified. On the basis of the N-terminal sequence of this protein, a cDNA clone of the Xyl gene was obtained by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequence of the 35-kDa protein shared similarities with the sequences of many microbial xylanases and a barley aleurone-layer xylanase. The 35-kDa protein in the pollen-coat extract was purified to homogeneity by fast protein liquid chromatography and determined to be an acidic endoxylanase that was most active on oat spelt xylan. Northern and in situ hybridization showed that Xyl was specifically expressed in the tapetum of the anther after the tetrad microspores had become individual microspores. Southern hybridization and gene-copy reconstruction studies showed only one copy of the Xyl gene per haploid genome. Analyses of the genomic DNA sequence of Xyl and RNase protection studies with the transcript revealed many regulatory motifs at the promoter region and an intron at the 5' leader region of the transcript. The Xyl transcript had a 562-nucleotide (nt) 5' leader, a 54-nt sequence encoding a putative signal peptide, a 933-nt coding sequence, and a 420-nt 3'-untranslated sequence. The unusually long 5' leader had an open reading frame encoding a putative 175-residue protein whose sequence was most similar to that of a microbial arabinosidase. The maize xylanase is the first enzyme documented to be present in the pollen coat. Its possible role in the hydrolysis of the maize type II primary cell wall (having xylose, glucose, and arabinose as the major moieties) of the tapetum cells and the stigma surface is discussed.
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PMID:The predominant protein on the surface of maize pollen is an endoxylanase synthesized by a tapetum mRNA with a long 5' leader. 1042 75

The expression and localization of the aquaporin-1 (AQP1) water channel were examined in the glomeruli of the human kidney. A ribonuclease protection assay showed the expression of AQP1 mRNA in human glomeruli but not in rat glomeruli. Western blot analysis revealed 28 kDa and 35 kDa bands corresponding to unglycosylated and glycosylated AQP1 proteins in human glomeruli. Immunoreactive AQP1 was demonstrated almost exclusively in the mesangium in the human glomeruli by immunohistochemistry. The endothelium of glomerular capillaries was only partly immunostained while podocytes and Bowman's capsule epithelia were not immunolabeled. Immunoelectron microscopy localized the immunoreactive AQP1 on the plasma membrane of mesangial cells in human glomeruli. The immouno-gold labeling was dense on the projections of mesangial cells protruding to the glomerular capillary lumen or to endothelial cells, but was sparse on other parts of the mesangial cell surface. No immunoreactivity for AQP1 was demonstrated in rat glomeruli. This study showed the distinct localization of AQP1 in the mesangial cells of human glomeruli, suggesting its role in water movement through these cells.
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PMID:Localization and expression of the aquaporin-1 water channel in mesangial cells in the human glomerulus. 1200 13

The coding region of c-myc mRNA encompassing the coding region determinant (CRD) nucleotides (nts) 1705-1792 is critical in regulating c-myc mRNA stability. This is in part due to the susceptibility of c-myc CRD RNA to attack by an endoribonuclease. We have previously purified and characterized a mammalian endoribonuclease that cleaves c-myc CRD RNA in vitro. This enzyme is tentatively identified as a 35 kDa RNase1-like endonuclease. In an effort to understand the sequence and secondary structure requirements for RNA cleavage by this enzyme, we have determined the secondary structure of the c-myc CRD RNA nts 1705-1792 using RNase probing technique. The secondary structure of c-myc CRD RNA possesses five stems; two of which contain 4 base pairs (stems I and V) and three consisting of 3 base pairs (stems II, III, and IV). Endonucleolytic assays using the c-myc CRD and several c-myc CRD mutants as substrates led to the following conclusions: (i) the enzyme prefers to cleave in between the dinucleotides UA, CA, and UG in single-stranded regions; (ii) the enzyme is more specific towards UA dinucleotides. These properties further distinguish the enzyme from previously described mammalian endonuclease that cleaves c-myc mRNA in vitro.
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PMID:Identification of c-myc coding region determinant RNA sequences and structures cleaved by an RNase1-like endoribonuclease. 1719 36

Many plant phytochemicals constitute binary enzyme-glucoside systems and function in plant defence. In brassicas, the enzyme myrosinase is confined to specific myrosin cells that separate the enzyme from its substrate; the glucosinolates. The myrosinase-catalysed release of toxic and bioactive compounds such as isothiocyanates, upon activation or tissue damage, has been termed 'the mustard oil bomb' and characterized as a 'toxic mine' in plant defence. The removal of myrosin cells and the enzyme that triggers the release of phytochemicals have been investigated by genetically modifying Brassica napus plants to remove myrosinase-storing idioblasts. A construct with the seed myrosin cell-specific Myr1.Bn1 promoter was used to express a ribonuclease, barnase. Transgenic plants ectopically expressing barnase were embryo lethal. Co-expressing barnase under the control of the Myr1.Bn1 promoter with the barnase inhibitor, barstar, under the control of the cauliflower mosaic virus 35S promoter enabled a selective and controlled death of myrosin cells without affecting plant viability. Ablation of myrosin cells was confirmed with light and electron microscopy, with immunohistological analysis and immunogold-electron microscopy analysis showing empty holes where myrosin cells normally are localized. Further evidence for a successful myrosin cell ablation comes from immunoblots showing absence of myrosinase and negligible myrosinase activity, and autolysis experiments showing negligible production of glucosinolate hydrolysis products. The plants where the myrosin defence cells have been ablated and named 'MINELESS plants'. The epithiospecifier protein profile and glucosinolate levels were changed in MINELESS plants, pointing to localization of myrosinases and a 35 kDa epithiospecifier protein in myrosin cells and a reduced turnover of glucosinolates in MINELESS plants.
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PMID:Removing the mustard oil bomb from seeds: transgenic ablation of myrosin cells in oilseed rape (Brassica napus) produces MINELESS seeds. 2021 77