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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The polyoma virus (Py) RNA species transcribed from the L DNA strand of the "late" region of the Py genome in Py-infected mouse cells have been mapped by hybridization with specific fragments of Py DNA followed by electron microscopic visualization of the hybrids. Total cellular polyadenylated Py-specific RNA molecules having an S value in the range of 16S to 20S were purified by oligodeoxythymidylic acidcellulose column chromatography, preparative hybridization with Py DNA, and sucrose gradient centrifugation. Cytoplasmic Py-specific RNA was similarily purified, except that it was not fractionated by sucrose gradient centrifugation. Hybrids of these RNA molecules and Py DNA fragments were spread for electron microscopy by either the cytochrome c technique or the bacteriophage T4 gene 32 protein method. The polyadenylic acid at the 3'-end of the RNA in the hybrids was identified by labeling with simian virus 40 DNA circles to which polybromodeoxyuridylic acid tails had been covalently attached. These experiments revealed the presence of three L DNA strand transcripts in both RNA preparations. Two of these RNA molecules were found to be spliced from chains transcribed from two noncontiguous parts of the late region. The third molecule either is a continuous transcript of the entire late region or contains a splicing feature which is too small to be reliably observed by the electron microscope methods used. The 5'-ends of the three RNA species map within a region extending from 68 to 70 map units on the Py restriction endonuclease map. Each of the two spliced molecules contains a 5'-terminal leader sequence transcribed from a DNA segment with an estimated length of 60 to 110 nuvleotides. The 3'-ends of the leaders map at 66.7 +/- 1.0 and 66.4 +/- 0.50 map units. In these molecules the 5'-ends of the other part (the main body) map at 59.4 +/- 0.90 and 49.4 +/- 2.0 map units, respectively. The 3'-termini of all three RNA species map at 24 to 25 map units.
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PMID:Electron microscopic mapping of RNA transcribed from the late region of polyoma virus DNA. 23 79

Ammonium sulfate fractionation of a Saccharomyces cerevisiae whole-cell extract yielded a preparation which carried out correct and efficient endonucleolytic cleavage and polyadenylation of yeast precursor mRNA substrates corresponding to a variety of yeast genes. These included CYC1 (iso-1-cytochrome c), HIS4 (histidine biosynthesis), GAL7 (galactose-1-phosphate uridyltransferase), H2B2 (histone H2B2), PRT2 (a protein of unknown function), and CBP1 (cytochrome b mRNA processing). The reaction processed these pre-mRNAs with varying efficiencies, with cleavage and polyadenylation exceeding 70% in some cases. In each case, the poly(A) tail corresponded to the addition of approximately 60 adenosine residues, which agrees with the usual length of poly(A) tails formed in vivo. Addition of cordycepin triphosphate or substitution of CTP for ATP in these reactions inhibited polyadenylation but not endonucleolytic cleavage and resulted in accumulation of the cleaved RNA product. Although this system readily generated yeast mRNA 3' ends, no processing occurred on a human alpha-globin pre-mRNA containing the highly conserved AAUAAA polyadenylation signal of higher eucaryotes. This sequence and adjacent signals used in mammalian systems are thus not sufficient to direct mRNA 3' end formation in yeast. Despite the lack of a highly conserved nucleotide sequence signal, the same purified fraction processed the 3' ends of a variety of unrelated yeast pre-mRNAs, suggesting that endonuclease cleavage and polyadenylation may produce the mature 3' ends of all mRNAs in S. cerevisiae.
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PMID:RNA processing in vitro produces mature 3' ends of a variety of Saccharomyces cerevisiae mRNAs. 216 May 81

The assembly of the respiratory apparatus requires the coordinate expression of a large number of genes from both nuclear and mitochondrial genetic systems. In vertebrate organisms, the molecular mechanisms integrating the activities of these distinct genomic compartments in response to tissue demands for respiratory energy remain unknown. A potential inroad to this problem came with the discovery of nuclear respiratory factor 1 (NRF-1), a novel transcriptional activator defined by mutational and DNA binding analysis of the somatic cytochrome c promoter. Functional NRF-1 sites are now observed in several other recently isolated nuclear genes whose products function in the mitochondria. Among these are genes encoding subunits of the cytochrome c oxidase (subunit VIc) and reductase (ubiquinone-binding protein) complexes. In addition, a functional NRF-1 site resides in the MRP RNA gene encoding the RNA moiety of a ribonucleoprotein endonuclease involved in mitochondrial DNA replication. Synthetic oligomers of these sites competitively displace NRF-1 binding to the cytochrome c promoter. NRF-1-binding activities for each site also have the same thermal lability, copurify chromatographically, and make similar guanosine nucleotide contacts within each recognition sequence. Moreover, NRF-1 recognition in vitro correlates with the ability of each site to stimulate expression in vivo from a truncated cytochrome c promoter. The presence of NRF-1-binding sites in nuclear genes encoding structural components of the mammalian electron transport chain, as well as the mitochondrial DNA replication machinery, suggests a mechanism for coordination of nuclear and mitochondrial genetic systems through the concerted modulation of nuclear genes.
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PMID:NRF-1: a trans-activator of nuclear-encoded respiratory genes in animal cells. 216 1

The product of the Rous sarcoma virus (RSV) gag gene, Pr76gag, is a polyprotein precursor which is cleaved by the viral protease to yield the major structural proteins of the virion during particle assembly in avian host cells. We have recently shown that myristylated forms of the RSV Gag protein can induce particle formation with very high efficiency when expressed in mammalian cells (J. W. Wills, R. C. Craven, and J. A. Achacoso, J. Virol. 63:4331-4343, 1989). We made use of this mammalian system to examine the abilities of foreign antigens to be incorporated into particles when fused directly to the myristylated Gag protein. Our initial experiments showed that removal of various portions of the viral protease located at the carboxy terminus of the RSV Gag protein did not disrupt particle formation. We therefore chose this region for coupling of iso-1-cytochrome c from Saccharomyces cerevisiae to Gag. This was accomplished by constructing an in-frame fusion of the CYC1 and gag coding sequences at a common restriction endonuclease site. Expression of the chimeric gene resulted in synthesis of the Gag-cytochrome fusion protein and its release into the cell culture medium. The chimeric particles were readily purified by simple centrifugation, and transmission electron microscopy of cells that produced them revealed a morphology similar to that of immature type C retrovirions.
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PMID:Incorporation of chimeric gag protein into retroviral particles. 216 12

Cationic proteins--cytochrome c and pancreatic RNAase--possess the apurinic-apyrimidinic DNA-endonuclease activity. The affinity of these proteins for DNA-apurinic sites does not differ from that of specific apurinic DNA-endonucleases described in literature. The main features of the apurinic activity of cationic proteins are as follows: low specific activity, high temperature optimum of the reaction, absence of primer-stimulated activity. The feasibility of participation of cationic proteins and some other nucleophilic compounds in single-stranded breaks production in apurinic DNA is discussed.
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PMID:[Apurinic-apyrimidinic DNA-endonuclease activity of cytochrome c and pancreatic RNAse]. 242 Mar 74

In whole cell extracts of Saccharomyces cerevisiae, incubation of precursor mRNA transcripts encoding the sequences essential in vivo for forming the 3' end of the iso-1-cytochrome c mRNA (CYC1) revealed an endonuclease activity with the characteristics required for producing the mature mRNA 3' end. The observed cleavage in vitro is (i) accurate, occurring at or near the polyadenylation site of CYC1 RNA, (ii) 30 to 50 percent efficient, (iii) adenosine triphosphate dependent, (iv) specific for the 3' ends of at least two yeast pre-mRNA's, and (v) absent with related pre-mRNA's carrying mutations that abolish correct 3' end formation in vivo. In addition, a second activity in the extract polyadenylates the product under appropriate conditions. Thus, the mature 3' ends of yeast mRNA's may be generated by endonucleolytic cleavage and polyadenylation rather than by transcription termination.
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PMID:RNA processing generates the mature 3' end of yeast CYC1 messenger RNA in vitro. 284 17

The CYC7-H2 mutation in the yeast Saccharomyces cerevisiae was caused by insertion of a Ty1 transposable element in front of the iso-2-cytochrome c structural gene, CYC7. The Ty1 insertion places iso-2-cytochrome c production under control of regulatory signals that are normally required for mating functions in yeast cells. We have investigated the regions of the Ty1 insertion that are responsible for the aberrant production of iso-2-cytochrome c in the CYC7-H2 mutant. Five alterations of the CYC7-H2 gene were obtained by specific restriction endonuclease cleavage of the cloned DNA and ligation of appropriate fragments. The CYC7+, CYC7-H2, and modified CYC7-H2 genes were each inserted into the yeast vector YIp5 and used to transform a cytochrome c-deficient yeast strain. Expression and regulation of each allele integrated at the CYC7 locus have been compared in vivo by determination of the amount of iso-2-cytochrome c produced. These results show that distal regions of the Ty1 element are not essential for the CYC7-H2 overproducing phenotype. In contrast, alterations in the vicinity of the proximal Ty1 junction abolish the CYC7-H2 expression and give rise to different phenotypes.
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PMID:Identification of regulatory regions within the Ty1 transposable element that regulate iso-2-cytochrome c production in the CYC7-H2 yeast mutant. 609 68

The two apocytochrome c proteins of yeast are coded for by separate genes. Iso-2-cytochrome c differs from the iso-1 protein at 17 positions within a homologous sequence of 108 amino acids. The previously cloned iso-1-cytochrome c coding sequence has been used to identify lambda-yeast recombinant phage containing the gene for iso-2-cytochrome c. The latter protein contains the dipeptide Ala-Ala which is coded for by the nucleic acid sequence G-C-N-G-C-N. The recognition specificity of restriction endonuclease Fnu4HI for G-C-N-G-C provided a rapid means of locating the region of the cloned fragment which codes for iso-2-cytochrome c. The DNA sequence of this gene has been determined and compared with that of the iso-1-cytochrome c locus. There is no intervening sequence within the gene for iso-2-cytochrome c. At 45 of the 91 positions for which iso-1- and iso-2-cytochrome c have the same amino acid, the codons differ. Such third position variation does not occur within the region coding for amino acids 70-80, the protein sequence that is also most conserved among all eukaryotic cytochromes c.
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PMID:Isolation and sequence of the gene for iso-2-cytochrome c in Saccharomyces cerevisiae. 624 66

We have constructed a plasmid that selectively integrates adjacent to the CYC1 locus, which determines iso-1-cytochrome c in the yeast Saccharomyces cerevisiae. Different CYC1 alleles can be conveniently recovered by digestion of total DNA from transformed strains with BgI II, a restriction endonuclease that does not cut the vector or the CYC1 gene, followed by transformation of Escherichia coli, selecting the ampicillin resistance gene carried on the original vector. This procedure was used to clone the cyc1-362 gene, which contains an alteration in front of the AUG initiation codon. The cyc1-362 mutational causes a deficiency of the iso-1-cytochrome c protein but still allows transcription of the iso-1-cytochrome c mRNA. DNA sequence analysis showed that the cyc1-362 mutation consisted of two single-base-pair substitutions, producing an A leads to G change 18 nucleotides and a G leads to A change 30 nucleotides in front of the AUG initiation codon in the mRNA. The A leads to G change at position -18 resulted in the creation of an AUG triplet, which is proximal to the normal initiation site and out of phase with the normal reading frame. The deficiency of iso-1-cytochrome c is most simply explained by assuming that translation initiates at the more proximal abnormal AUG site but not at the normal AUG site.
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PMID:DNA sequence of a mutation in the leader region of the yeast iso-1-cytochrome c mRNA. 626 5

We use a rat cytochrome c gene that we previously isolated and determined the sequence of to estimate the number of related sequences present in the rat genome. Approximately 25 different EcoRI restriction endonuclease fragments from total rat DNA hybridize to the gene of known structure. Four of these correspond to homologous sequences present in four different lambda Charon 4A-rat cytochrome c recombinants previously isolated. Intact or nearly intact genes appear to reside on almost all of the genomic fragments, because they hybridize strongly to gene subfragments representing both 5' and 3' portions of the coding sequence as well as to 3' noncoding DNA that is found specifically associated with the coding region. A subgroup of about six of the fragments also shares homology within the 73 nucleotides immediately preceding the AUG codon. An intron-specific probe reveals only the EcoRI fragment from which it was derived and one other genomic fragment. On the basis of the temperature of complete dissociation of the coding region probe in 0.75 M NaCl/0.075 M Na3 citrate/50% (vol/vol) formamide, the 25 fragments are separable into three stringency classes of 40-50 degrees C, 50-55 degrees C, and 55-60 degrees C. The latter, high-stringency group of about seven fragments includes those cloned in the recombinant phage isolates, whose regions homologous to cytochrome c are shown to differ from the purified gene of known sequence by an amount equivalent to about 2% mismatched bases. Families of cytochrome c gene-related sequences are also found in the genomes of several other mammals, including humans.
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PMID:Cytochrome c gene-related sequences in mammalian genomes. 627 93


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