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)

Surfactant is a lipoprotein substance that is synthesized and secreted by alveolar type II epithelial cells and acts to reduce surface tension at the air-alveolar interface. SP-C is a 5,000-D molecular weight, hydrophobic, surfactant-associated protein. In the present study, we used a ribonuclease protection assay to show that SP-C mRNA is induced in rabbit fetal lung tissue early in development, increases in relative concentration as development proceeds, and is present in maximal concentration at term (31 days of gestation). We also used the technique of in situ hybridization to localize SP-C mRNA in fetal, neonatal, and adult rabbit lung tissue. SP-C mRNA was present in all of the epithelial cells of the prealveolar region of day 19 gestational age rabbit fetal lung tissue, i.e., about 7 days before the appearance of differentiated alveolar type II cells in the fetal lung tissue. By day 27 of gestation, SP-C mRNA was restricted to epithelial cells with the morphologic characteristics of alveolar type II cells. SP-C mRNA was not detected in bronchiolar epithelium at any stage of lung development. The intensity of SP-C mRNA hybridization in the prealveolar and alveolar type II epithelial cells increased as a function of gestational age and was maximal at term. The pattern of SP-C mRNA localization in neonatal and adult rabbit lung tissue was consistent with the restriction of SP-C gene expression to differentiated alveolar type II cells. Our data are suggestive that SP-C may serve some as yet unknown function early in lung development because it is present in fetal lung prealveolar epithelial cells much earlier in gestation than are differentiated, surfactant-producing alveolar type II cells.
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PMID:Localization of surfactant-associated protein C (SP-C) mRNA in fetal rabbit lung tissue by in situ hybridization. 154 Mar 86

The Mov-34 mutation is a recessive embryonic lethal mutation caused by experimental introduction of a recombinant Moloney murine leukemia provirus into the mouse germline. We have cloned a full-length cDNA from the Mov-34 gene, the transcription unit disrupted by the proviral integration. This cDNA is predicted to encode a novel 321-amino acid, 36-kDa protein of unknown function. Overlapping phage lambda clones containing the entire Mov-34 gene have been isolated. The Mov-34 gene spans just over 8 kb and contains seven exons. The 5' flanking region of the Mov-34 gene contains neither "TATA" nor "CAAT" box sequences, and 5' end mapping by primer extension and ribonuclease protection reveal multiple transcription initiation sites.
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PMID:The murine Mov-34 gene: full-length cDNA and genomic organization. 183 87

Ribonuclease H activities present in fully grown Xenopus oocytes were investigated by using either liquid assays or renaturation gel assays. Whereas the test in solution detected an apparently unique class I ribonuclease H activity, the activity gels did not detect this enzyme but another one with the molecular weight expected for a class II ribonuclease H. The ribonuclease HI was found to be primarily concentrated in the germinal vesicle, but around 5% of this activity was detectged in the cytoplasm and may correspond to the activity involved in antisense oligonucleotide-mediated destruction of messenger RNAs. The concentration of this class I ribonuclease H in oocytes is similar to that in somatic cells. The class II ribonuclease H remained undetectable by the test in solution because its activity was cryptic. On activity gel, a polypeptide with the apparent molecular mass of 32 kDa, expected for a ribonuclease HII, was found to be concentrated in mitochondria although no RNase H activity could be detected by using the liquid assay. Based on sedimentation studies, we hypothesize that the apparent absence of RNase H activity in solution could be the result of the association of this 32-kDa polypeptide with other polypeptides, or possibly nucleic acids, to form a multimer of, until now, unknown function.
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PMID:Characterization and subcellular localization of ribonuclease H activities from Xenopus laevis oocytes. 792 7

The nucleotide sequences of the Rhodobacter sphaeroides hemA and hemT genes, encoding 5-aminolevulinic acid (ALA) synthase isozymes, were determined. ALA synthase catalyzes the condensation of glycine and succinyl coenzyme A, the first and rate-limiting step in tetrapyrrole biosynthesis. The hemA and hemT structural gene sequences were 65% identical to each other, and the deduced HemA and HemT polypeptide sequences were 53% identical, with an additional 16% of aligned amino acids being similar. HemA and HemT were homologous to all characterized ALA synthases, including two human ALA synthase isozymes. In addition, they were evolutionarily related to 7-keto-8-aminopelargonic acid synthetase (BioF) and 2-amino-3-ketobutyrate coenzyme A ligase (Kbl), enzymes which catalyze similar reactions. Two hemA transcripts were identified, both expressed under photosynthetic conditions at levels approximately three times higher than those found under aerobic conditions. A single transcriptional start point was identified for both transcripts, and a consensus sequence at this location indicated that an Fnr-like protein may be involved in the transcriptional regulation of hemA. Transcription of hemT was not detected in wild-type cells under the physiological growth conditions tested. In a mutant strain in which the hemA gene had been inactivated, however, hemT was expressed. In this mutant, hemT transcripts were characterized by Northern (RNA) hybridization, primer extension, and ribonuclease protection techniques. A small open reading frame of unknown function was identified upstream of, and transcribed in the same direction as, hemA.
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PMID:Expression of the Rhodobacter sphaeroides hemA and hemT genes, encoding two 5-aminolevulinic acid synthase isozymes. 846 90

Mammalian secretory ribonucleases (RNases 1) form a family of extensively studied homologous proteins that were already used for phylogenetic analyses at the protein sequence level previously. In this paper we report the determination of six ribonuclease gene sequences of Artiodactyla and two of Cetacea. These sequences have been used with ruminant homologues in phylogenetic analyses that supported a group including hippopotamus and toothed whales, a group of ruminant pancreatic and brain-type ribonucleases, and a group of tylopod sequences containing the Arabian camel pancreatic ribonuclease gene and Arabian and Bactrian camel and alpaca RNase 1 genes of unknown function. In all analyses the pig was the first diverging artiodactyl. This DNA-based tree is compatible to published trees derived from a number of other genes. The differences to those trees obtained with ribonuclease protein sequences can be explained by the influence of convergence of pancreatic RNases from hippopotamus, camel, and ruminants and by taking into account the information from third codon positions in the DNA-based analyses. The evolution of sequence features of ribonucleases such as the distribution of positively charged amino acids and of potential glycosylation sites is described with regard to increased double-stranded RNA cleavage that is observed in several cetacean and artiodactyl RNases which may have no role in ruminant or ruminant-like digestion.
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PMID:Inclusion of cetaceans within the order Artiodactyla based on phylogenetic analysis of pancreatic ribonuclease genes. 1009 26

Six open reading frames (ORFs) from Saccharomyces cerevisiae chromosome VII were deleted using the kanMX4 module and the long-flanking homology-PCR replacement strategy in at least two different backgrounds. Among these ORFs, two of them (YGL100w and YGL094c) are now known genes which encode well-characterized proteins (Seh1p, a nuclear pore protein, and Pan2p, a component of Pab1p-stimulated poly(A) ribonuclease, respectively). The other four ORFs (YGL101w, YGL099w, YGL098w and YGL096w) code for proteins of unknown function, although the protein encoded by YGL101w has a strong similarity to the hypothetical protein Ybr242p. Gene disruptions were performed in diploid cells using the KanMX4 cassette, and the geneticin (G418)-resistant transformants were checked by PCR. Tetrad analysis of heterozygous deletant strains revealed that YGL098w is an essential gene for vegetative growth in three backgrounds, whereas the other five genes are non-essential, although we have found some phenotypes in one of them. YGL099wDelta strain did not grow at all at 15 degrees C and showed a highly impaired sporulation and a significantly lower mating efficiency. The other three deletants did not reveal any significant differences with respect to their parental strains in our basic phenotypic tests.
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PMID:Disruption and phenotypic analysis of six open reading frames from the left arm of Saccharomyces cerevisiae chromosome VII. 1066 74

We present here the structure of Yer010c protein of unknown function, solved by Multiple Anomalous Diffraction and revealing a common fold and oligomerization state with proteins of the regulator of ribonuclease activity A (RraA) family. In Escherichia coli, RraA has been shown to regulate the activity of ribonuclease E by direct interaction. The absence of ribonuclease E in yeast suggests a different function for this family member in this organism. Yer010cp has a few supplementary secondary structure elements and a deep pseudo-knot at the heart of the protein core. A tunnel at the interface between two monomers, lined with conserved charged residues, has unassigned residual electron density and may constitute an active site for a yet unknown activity.
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PMID:Crystal structure of yeast YER010Cp, a knotable member of the RraA protein family. 1619 57

Polyphosphate (polyP) is a linear polymer consisting of tens to hundreds of phosphate molecules joined together by high-energy anhydride bonds. These polymers are found in virtually all prokaryotic and eukaryotic cells and perform many functions; prominent among them are the responses to many stresses. Polyphosphate is synthesized by polyP kinase (PPK), using the terminal phosphate of ATP as the substrate, and degraded to inorganic phosphate by both endo- and exopolyphosphatases. Here we report the crystal structure and analysis of the polyphosphate phosphatase PPX from Escherichia coli O157:H7 refined at 2.2 Angstroms resolution. PPX is made of four domains. Domains I and II display structural similarity with one another and share the ribonuclease-H-like fold. Domain III bears structural similarity to the N-terminal, HD domain of SpoT. Domain IV, the smallest domain, has structural counterparts in cold-shock associated RNA-binding proteins but is of unknown function in PPX. The putative PPX active site is located at the interface between domains I and II. In the crystal structure of PPX these two domains are close together and represent the "closed" state. Comparison with the crystal structure of PPX/GPPA from Aquifex aeolicus reveals close structural similarity between domains I and II of the two enzymes, with the PPX/GPPA representing an "open" state. A striking feature of the dimer is a deep S-shaped canyon extending along the dimer interface and lined with positively charged residues. The active site region opens to this canyon. We postulate that this is a likely site of polyP binding.
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PMID:The structure of the exopolyphosphatase (PPX) from Escherichia coli O157:H7 suggests a binding mode for long polyphosphate chains. 1667 53

The complete DNA sequence of the mildly virulent Gallid herpesvirus type 2 strain CU-2 was determined and consists of 176,922 bp with an overall gene organization typical of class E herpesviruses. Phylogenetically, this strain partitions in its own branch between the virulent strains RB-1B, Md11, and Md5, and the vaccine strain CVI988. Overall, the genome of CU-2 is more similar to that of CVI988, with identically sized unique short regions of 11,651 bp. As in CVI988, an insertion of 177 bp was identified in the overlapping genes encoding the Meq, RLORF6, and 23 kDa proteins within the repeat long region of the genome. A total of 15 single nucleotide polymorphisms (SNPs) common to both CU-2 and CVI988, and not occurring in virulent strains, were identified in the genes encoding UL29, UL45, UL50, UL52, LORF10, RLORF14a, RLORF12, Meq(RLORF7), 23kDa, ICP4, US3, and two hypothetical proteins MDV071.4 and MDV076.4. Each gene encoding UL29 and Meq contained two SNPs. Only one major open reading frame (ORF) encoding UL41, the virus host shutoff (VHS) ribonuclease, was disrupted in the CU-2 genome. An additional cytosine after the 25 codon is predicted to produce a truncated protein of 97 aa. Since GaHV-2 mutants lacking UL41 have been reported to retain their virulence, other factors are likely responsible for the low virulence of CU-2. It is largely suspected that SNPs in common with CVI988 along with the insertions in the Meq loci are responsible for its phenotype. Conversely, we identified 43 nonsynonymous mutations (within 23 genes) that may contribute to the virulence of CU-2. These SNPs are shared exclusively with all sequenced virulent strains (Md5, Md11, and RB-1B) and not present within the CVI988 genome. Although most occur in proteins of unknown function, a significant percentage is in proteins involved in virion assembly.
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PMID:Sequence determination of a mildly virulent strain (CU-2) of Gallid herpesvirus type 2 using 454 pyrosequencing. 1835 49

The broad cellular actions of RNase III family enzymes include ribosomal RNA (rRNA) processing, mRNA decay, and the generation of noncoding microRNAs in both prokaryotes and eukaryotes. Here we report that YmdB, an evolutionarily conserved 18.8-kDa protein of Escherichia coli of previously unknown function, is a regulator of RNase III cleavages. We show that YmdB functions by interacting with a site in the RNase III catalytic region, that expression of YmdB is transcriptionally activated by both cold-shock stress and the entry of cells into stationary phase, and that this activation requires the sigma-factor-encoding gene, rpoS. We discovered that down-regulation of RNase III activity occurs during both stresses and is dependent on YmdB production during cold shock; in contrast, stationary-phase regulation was unperturbed in YmdB-null mutant bacteria, indicating the existence of additional, YmdB-independent, factors that dynamically regulate RNase III actions during normal cell growth. Our results reveal the previously unsuspected role of ribonuclease-binding proteins in the regulation of RNase III activity.
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PMID:YmdB: a stress-responsive ribonuclease-binding regulator of E. coli RNase III activity. 1914 81


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