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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Comparative studies have been undertaken on the higher order structure of ribosomal 5S RNAs from diverse origins. Competitive reassociation studies show that 5S RNA from either a eukaryote or archaebacterium will form a stable ribonucleoprotein complex with the yeast ribosomal 5S RNA binding protein (YL3); in contrast, eubacterial RNAs will not compete in a similar fashion. Partial S1 ribonuclease digestion and ethylnitrosourea reactivity were used to probe the structural differences suggested by the reconstitution experiments. The results indicate a more compact higher order structure in eukaryotic 5S RNAs as compared to eubacteria and suggest that the archaebacterial 5S RNA contains features which are common to either group. The potential significance of these results with respect to a generalized model for the tertiary structure of the ribosomal 5S RNA and to the heterogeneity in the protein components of 5S RNA-protein complexes are discussed.
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PMID:Evolutionary changes in the higher order structure of the ribosomal 5S RNA. 354 23

We produced a B cell hybridoma (TW2.3) from vaccinia virus-infected mice that secreted a monoclonal antibody (MAb) reactive with a 25-kDA early viral protein that was localized by laser scanning confocal microscopy to the nucleus and cytoplasmic viral factory regions of infected cells. By cell-free translation of mRNA selected by hybridization to a complete library of vaccinia virus DNA fragments, the immunoreactive polypeptide was mapped to open reading frame E3L. The RNA start site of an early promoter was located 26 nucleotides upstream of the first methionine codon of E3L. Evidence was obtained that translation initiation occurs in vivo and in vitro at both the first and second methionine codons to produce major and minor polypeptides of 25 and 19 kDa, respectively. Both polypeptides bound double-stranded RNA, confirming the recent report of H.-W. Chang, J. C. Watson, and B. L. Jacobs (Proc. Natl. Acad. Sci. USA 89, 4825-4829, 1992). Other vaccinia virus proteins were not required for the nuclear localization of the E3L protein, since MAb TW2.3 bound to the nuclei of uninfected cells that were transfected with the E3L gene under the control of the SV40 early promoter. We also demonstrated that the E3L protein can bind to nuclei of aldehyde fixed and detergent permeabilized uninfected cells. This binding was abrogated by treatment of the cells with RNase but not DNase. The nuclear and cytoplasmic locations of the double-stranded RNA binding protein are consistent with multiple functions in the vaccinia virus infectious cycle.
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PMID:Nuclear localization of a double-stranded RNA-binding protein encoded by the vaccinia virus E3L gene. 833 42

We have isolated the gene that encodes the neural-specific RNA binding protein HuD in the mouse (Elavl4), and have mapped its location to the mid-distal region of chromosome 4, close to the neurological mutant clasper. The coding region of the Elavl4 gene covers approximately 44 kb; the first two RNA binding domains (RBDs) that are homologous to the two RBDs found in the Drosophila sex-lethal gene are each encoded in two exons, whereas the third RBD is encoded in a single exon. Elavl4 mRNAs are alternatively spliced in the region between RBDs 2 and 3 due to the variable use of two micro-exons, and RNase protection analysis indicates that two of four possible splice variants are the predominant isoforms expressed in the central nervous system. The high degree of sequence conservation between the Hu proteins suggests that the exon organization of all the Hu protein genes will be similar, if not identical, to the Elavl4 gene.
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PMID:Gene organization and chromosome location of the neural-specific RNA binding protein Elavl4. 952 51

RNase MRP is a ribonucleoprotein endoribonuclease that has been shown to have roles in both mitochondrial DNA replication and nuclear 5.8S rRNA processing. SNM1 encodes an essential 22.5-kDa protein that is a component of yeast RNase MRP. It is an RNA binding protein that binds the MRP RNA specifically. This 198-amino-acid protein can be divided into three structural regions: a potential leucine zipper near the amino terminus, a binuclear zinc cluster in the middle region, and a serine- and lysine-rich region near the carboxy terminus. We have performed PCR mutagenesis of the SNM1 gene to produce 17 mutants that have a conditional phenotype for growth at different temperatures. Yeast strains carrying any of these mutations as the only copy of snm1 display an rRNA processing defect identical to that in MRP RNA mutants. We have characterized these mutant proteins for RNase MRP function by examining 5.8S rRNA processing, MRP RNA binding in vivo, and the stability of the RNase MRP RNA. The results indicate two separate functional domains of the protein, one responsible for binding the MRP RNA and a second that promotes substrate cleavage. The Snm1 protein appears not to be required for the stability of the MRP RNA, but very low levels of the protein are required for processing of the 5.8S rRNA. Surprisingly, a large number of conditional mutations that resulted from nonsense and frameshift mutations throughout the coding regions were identified. The most severe of these was a frameshift at amino acid 7. These mutations were found to be undergoing translational suppression, resulting in a small amount of full-length Snm1 protein. This small amount of Snm1 protein was sufficient to maintain enough RNase MRP activity to support viability. Translational suppression was accomplished in two ways. First, CEN plasmid missegregation leads to plasmid amplification, which in turn leads to SNM1 mRNA overexpression. Translational suppression of a small amount of the superabundant SNM1 mRNA results in sufficient Snm1 protein to support viability. CEN plasmid missegregation is believed to be the result of a prolonged telophase arrest that has been recently identified in RNase MRP mutants. Either the SNM1 gene is inherently susceptible to translational suppression or extremely small amounts of Snm1 protein are sufficient to maintain essential levels of MRP activity.
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PMID:Mutagenesis of SNM1, which encodes a protein component of the yeast RNase MRP, reveals a role for this ribonucleoprotein endoribonuclease in plasmid segregation. 1052 74

SsrA RNA acts as a tRNA and mRNA to modify proteins whose synthesis on ribosomes has stalled. Such proteins are marked for degradation by addition of peptide tags to their C termini in a reaction mediated by SsrA RNA and SmpB, a specific SsrA-RNA binding protein. Evidence is presented here for the existence of a larger ribonucleoprotein complex that contains ribosomal protein S1, phosphoribosyl pyrophosphate synthase, RNase R, and YfbG in addition to SsrA RNA and SmpB. Biochemical, genetic, and phylogenetic results suggest potential roles for some of these factors in various stages of the ribosome rescue and tagging process and/or the presence of functional interactions between one or more of these proteins and SsrA.
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PMID:Protein factors associated with the SsrA.SmpB tagging and ribosome rescue complex. 1124 28

RNA interference (RNAi) is a biological process in which animal and plant cells destroy double-stranded RNA (dsRNA) and consequently the mRNA that shares sequence homology to the dsRNA. Although it is known that the enzyme Dicer is responsible for the digestion of dsRNA into approximately 22 bp fragments, the mechanism through which these fragments are associated with the RNA-induced silencing complex (RISC) is mostly unknown. To find protein components in RISC that interact with the approximately 22 bp fragment, we synthesized a (32)P- and photoaffinity moiety-labeled 22 bp dsRNA fragment and used it as bait to fish out protein(s) directly interacting with the dsRNA fragment. One of the proteins that we discovered by mass spectrometric analysis was TB-RBP/translin. Further analysis of this DNA/RNA binding protein showed that it possesses both ssRNase and dsRNase activities but not DNase activity. The protein processes long dsRNA mainly into approximately 25 bp fragments by binding to the open ends of dsRNA and cutting it with almost no turnover due to its high affinity toward the products. The activity requires physiological ionic strength. However, with single-stranded RNA as substrate, the digestion appeared to be more complete. Both ssRNase and dsRNase activities are inhibited by high levels of common RNase inhibitors. Interestingly, both activities can be enhanced greatly by EDTA.
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PMID:Testis brain ribonucleic acid-binding protein/translin possesses both single-stranded and double-stranded ribonuclease activities. 1549 Nov 49

The ribonuclease Drosha requires a dedicated double-stranded RNA binding protein to convert long, nuclear primary microRNA transcripts into shorter pre-microRNA stem-loops, the cytoplasmic precursors from which mature microRNAs are ultimately excised.
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PMID:MicroRNA biogenesis: drosha can't cut it without a partner. 1566 59

The expression of human inducible NO synthase (iNOS) is regulated both by transcriptional and post-transcriptional mechanisms. Stabilization of mRNAs often depends on activation of p38 mitogen-activated protein kinase (p38 MAPK). In human DLD-1 cells, inhibition of p38 MAPK by the compound 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580) or by overexpression of a dominant-negative p38 MAPKalpha protein resulted in a reduction of human iNOS mRNA and protein expression, whereas human iNOS promoter activity was not affected. An important RNA binding protein regulated by the p38 MAPK pathway and involved in the regulation of the stability of several mRNAs is tristetraprolin. RNase protection, quantitative real-time polymerase chain reaction, and Western blot experiments showed that cytokines used to induce iNOS expression in DLD-1 cells also enhanced tristetraprolin expression. SB203580 incubation reduced cytokine-mediated enhancement of tristetraprolin expression. Overexpression or down-regulation of tristetraprolin in stably transfected DLD-1- or A549/8 cells consistently resulted in enhanced or reduced iNOS expression by modulating iNOS-mRNA stability. In UV cross-linking experiments, recombinant tristetraprolin did not interact with the human iNOS mRNA. However, coimmunoprecipitation experiments showed interaction of tristetraprolin with the KH-type splicing regulatory protein (KSRP), which is known to recruit mRNAs containing AU-rich elements to the exosome for degradation. This tristetraprolin-KSRP interaction was enhanced by cytokines and reduced by SB203580 treatment. We conclude that tristetraprolin positively regulates human iNOS expression by enhancing the stability of human iNOS mRNA. Because tristetraprolin does not directly bind to the human iNOS mRNA but interacts with KSRP, tristetraprolin is likely to stabilize iNOS mRNA by capturing the KSRP-exosome complex.
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PMID:Tristetraprolin regulates the expression of the human inducible nitric-oxide synthase gene. 1577 52

The localization of specific mRNAs can establish local protein gradients that generate and control the development of cellular asymmetries. While all evidence underscores the importance of the cytoskeleton in the transport and localization of RNAs, we have limited knowledge of how these events are regulated. Using a visual screen for motile proteins in a collection of GFP protein trap lines, we identified the Drosophila IGF-II mRNA-binding protein (Imp), an ortholog of Xenopus Vg1 RNA binding protein and chicken zipcode-binding protein. In Drosophila, Imp is part of a large, RNase-sensitive complex that is enriched in two polarized cell types, the developing oocyte and the neuron. Using time-lapse confocal microscopy, we establish that both dynein and kinesin contribute to the transport of GFP-Imp particles, and that regulation of transport in egg chambers appears to differ from that in neurons. In Drosophila, loss-of-function Imp mutations are zygotic lethal, and mutants die late as pharate adults. Imp has a function in Drosophila oogenesis that is not essential, as well as functions that are essential during embryogenesis and later development. Germline clones of Imp mutations do not block maternal mRNA localization or oocyte development, but overexpression of a specific Imp isoform disrupts dorsal/ventral polarity. We report here that loss-of-function Imp mutations, as well as Imp overexpression, can alter synaptic terminal growth. Our data show that Imp is transported to the neuromuscular junction, where it may modulate the translation of mRNA targets. In oocytes, where Imp function is not essential, we implicate a specific Imp domain in the establishment of dorsoventral polarity.
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PMID:Motility screen identifies Drosophila IGF-II mRNA-binding protein--zipcode-binding protein acting in oogenesis and synaptogenesis. 1828 12

Previous studies have demonstrated that the major storage protein RNAs found in the rice endosperm are transported as particles via actomyosin to specific subdomains of the cortical endoplasmic reticulum. In this study, we examined the potential role of OsTudor-SN, a major cytoskeletal-associated RNA binding protein, in RNA transport and localization. OsTudor-SN molecules occur as high-molecular-weight forms, the integrity of which are sensitive to RNase. Immunoprecipitation followed by RT-PCR showed that OsTudor-SN binds prolamine and glutelin RNAs. Immunofluorescence studies using affinity-purified antibodies show that OsTudor-SNs exists as particles in the cytoplasm, and are distributed to both the protein body endoplasmic reticulum (ER) and cisternal ER. Examination of OsTudor-SN particles in transgenic rice plants expressing GFP-tagged prolamine RNA transport particles showed co-localization of OsTudor-SN and GFP, suggesting a role in RNA transport. Consistent with this view, GFP-tagged OsTudor-SN is observed in living endosperm sections as moving particles, a property inhibited by microfilament inhibitors. Downregulation of OsTudor-SN by antisense and RNAi resulted in a decrease in steady state prolamine RNA and protein levels, and a reduction in the number of prolamine protein bodies. Collectively, these results show that OsTudor-SN is a component of the RNA transport particle, and may control storage protein biosynthesis by regulating one or more processes leading to the transport, localization and anchoring of their RNAs to the cortical ER.
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PMID:The cytoplasmic-localized, cytoskeletal-associated RNA binding protein OsTudor-SN: evidence for an essential role in storage protein RNA transport and localization. 1841 Apr 82


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