Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nuclear non-polyadenylated RNA from HeLa cells infected with adenovirus-2 was examined for the presence of molecules containing the first intervening sequence (IVS1) of the major late premessenger RNA. Four molecules with the approximate size of free IVS1 in sucrose gradients (1021 nucleotides) were separated by polyacrylamide gel electrophoresis and characterized by complementary methods: S1 nuclease mapping, susceptibility to debranching enzyme, RNAase-H-directed cleavage. The results indicate that the most abundant RNA form is the excised lariat IVS1. We also find linear IVS1 and a randomly nicked lariat, the latter probably being made during RNA isolation. The fourth RNA is a leader 1-IVS1 molecule. No truncated IVS1 which might indicate that IVS1 is excised by several cycle of cleavage-ligation was detected. A study of the distribution of the four RNAs in hnRNP shows that they are part of RNPs of about 70 S. However, each RNP has distinct sedimentation characteristics and sensitivity to salt dissociation. Together, the results suggest that the excised lariat IVS1 is released from the large late premRNP under the form of a 70 S RNP, where it is linearized.
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PMID:Nuclear non-polyadenylated RNAs containing the first intervening sequence of the major late premessenger RNA from adenovirus-2: characterization and distribution in ribonucleoproteins. 303 61

The present report describes the isolation of hnRNP complexes with sedimentation coefficients greater than 80 S from rat liver nuclei without the use of ribonuclease inhibitors. The RNA moiety from these complexes is heterogeneous in size, with a mean sedimentation coefficient of 16 S when assayed with polyacrylamide-formamide gel electrophoresis. About 3% of this RNA binds to oligo(dT)-cellulose, the size of the bound fraction being somewhat smaller than the bulk of the hnRNP-RNA. This poly(A) RNA contains two adenylate tracts, one with about 30 and the second with about 200 adenylate residues. Reverse transcription of the poly(A)-containing RNA and hybridization of the cDNA with their respective templates shows two well-defined frequency populations, the first one separated from the second by almost 2.5 logs in the R0t curve. The same distribution was found, whether the hybrids were analysed with S1 nuclease or hydroxyapatite. Both separated frequency classes hybridize to total genomic DNA, the abundant one at C0t values typical for repetitive and unique sequences, the scarce one only at C0t values typical for unique sequences. The two populations are also able to hybridize with polysomal polyadenylated mRNA, the dilution of both frequencies being very similar in the cytoplasm.
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PMID:Poly(A)- and oligo(A)-adjacent sequences in RNA from the large hnRNP complexes of rat liver. 616 64

HMGA2 is an architectural nuclear factor which plays an important role in development and tumorigenesis, but mechanisms regulating its expression are largely unknown. The proximal promoters of the mouse and human genes coding for HMGA2 contain a conserved polypyrimidine/polypurine (ppyr/ppur) element which constitutes a multiple binding site for Sp1 and Sp3 transcription factors. In the present study we report that this region can adopt a single-stranded DNA conformation, as demonstrated in vitro by S1 nuclease sensitivity on supercoiled plasmids, indicative of an intramolecular triple-helical H-DNA structure. Moreover, we find that PTB (polypyrimidine tract binding protein), a member of the hnRNP family, binds the pyrimidine strand of Hmga2 as well as similar ppyr/ppur elements of the c-Ki-ras (R.Y) and c-myc P1 promoters. Transfection experiments indicate that non-B-DNA conformers of the ppyr/ppur tract of the Hmga2 promoter contribute to positive transcriptional activity. We propose a transcriptional mechanism, acting on the Hmga2 non-B-DNA structure and functioning through interconversion between double-stranded and single-stranded DNA, that seems to be adopted by an increasing number of genes, mainly growth-related.
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PMID:A polypyrimidine/polypurine tract within the Hmga2 minimal promoter: a common feature of many growth-related genes. 1180 22