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

---

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

A nuclease S1 mapping procedure was used to identify sites accessible to nucleases in the 3'-noncoding region of the rabbit globin mRNAs. A complex structure was evident in the alpha-globin species, with one highly accessible single-stranded site, large portions in an accessible double-stranded configuration, and a portion not accessible to any of the nucleases. In the beta-globin mRNA, the region was more uniformly accessible to RNase T1 and to a cobra venom enzyme specific for double-stranded RNA, but it had only a single site highly accessible to a bulkier Neurospora endonuclease. The patterns of cleavage were nearly identical in the deproteinized mRNAs and in the mRNAs associated with polyribosomes in reticulocyte extracts. In both species, a zone of secondary structure occurred around the poly(A) junction. In each species, virtually all the molecules had a poly(A) sequence of at least 20-25 AMP residues. A periodicity in poly(A) size distribution was observed. These results indicate that the beginning of this sequence is well protected against degradation inside the cell and that zones of partial protection occur at measured intervals. In crude extracts, where the poly(A) is covered with proteins, this sequence was protected against nuclease digestion.
...
PMID:Structural features in the 3'-terminal region of polyribosome-bound rabbit globin messenger RNAs. 300 Oct 55

The molecular mechanisms whereby RNA polymerase, catabolite activator protein (CAP), and cyclic AMP (cAMP) participate in transcriptional regulation at the galactose operon have been probed by a variety of in vitro techniques. Interactions between purified proteins and promoter-containing DNA fragments were assayed by gel electrophoresis, by resistance to restriction endonuclease digestion, and by monitoring runoff transcripts. The data bear on the multiple functions that CAP performs in gal control. A CAP-cAMP complex can exclude RNA polymerase from one of the two overlapping promoter regions (P2), thereby targeting the enzyme to the other (P1); this process is markedly influenced by the cAMP level. In addition, a second CAP molecule is involved in a cooperative process, which, at low cAMP, is required for efficient formation of transcriptionally competent complexes at P1. This second CAP may serve to stabilize the 1:1:1 CAP-polymerase-gal DNA intermediate under physiological conditions, thus enhancing initiation from P1 relative to P2. Kinetic analysis reveals that the modest effect of CAP on the rate of P1 open complex formation can be resolved into about a 4-fold increase in the binding of RNA polymerase to the P1 region, plus a 1.5-fold elevation in the rate of isomerization of enzyme-promoter complexes to the open state.
...
PMID:Role of a second catabolite activator protein molecule in controlling initiation of transcription at the galactose operon of Escherichia coli. 302 95

To determine the nature of spontaneous mutational events in cellular genes in hamster cells, mutant adenine phosphoribosyltransferase (aprt) genes were cloned and the regions to which we mapped alterations were sequenced. A variety of nucleotide changes were found to occur in the 12 mutant genes analyzed. Most mutations were simple base-pair substitutions-transitions (both G X C----A X T and A X T----G X C) and transversions. The only multiple mutation was a simple transition next to a single-base-pair insertion. Of the 12 mutations, 4 were more complex, involving small deletions or duplications. Two of these were similar to previously described deletions in that they occurred between short direct sequence repeats. No hot spots were detected. Three independent mutations were characterized at one restriction endonuclease site, although no other mutations were detected in the nucleotides surrounding this site in other mutant strains. At a functional level, sequence changes were either in exons (resulting in missense and, in one instance, nonsense mutations) or at splicing sites.
...
PMID:DNA sequence analysis of spontaneous mutations at the aprt locus of hamster cells. 303 19

The gene catIII, encoding a type III enterobacterial chloramphenicol acetyltransferase, was cloned from the transmissible plasmid R387 into pBR322 and bacteriophage M13 mp8. Nucleotide sequence analysis of 1160 bp of DNA identified an open reading frame encoding a protein of 213 amino acid residues and a calculated molecular mass of 24965 Da. The predicted N-terminal sequence is identical with that determined by Edman degradation of chloramphenicol acetyltransferase purified from Escherichia coli harbouring R387. Sequences equivalent to the consensus motifs for initiation and rho-factor-independent termination of transcription in E. coli occur 5' and 3' to the catIII open reading frame. In contrast with the catI gene, present on transposon Tn9 and many enterobacterial plasmids, expression of catIII is not subject to cyclic AMP-mediated catabolite repression in vivo and there is no sequence in the 5' non-coding DNA that resembles that deduced as the consensus for the binding of cyclic AMP receptor protein. Unique restriction-endonuclease cleavage sites were introduced adjacent to the catIII reading frame by using oligonucleotide-directed mutagenesis to facilitate insertion into E. coli expression vectors. Fully active chloramphenicol acetyltransferase represents 30-50% of the soluble protein component of cell-free extracts of E. coli containing the appropriate plasmids.
...
PMID:Nucleotide sequence analysis and overexpression of the gene encoding a type III chloramphenicol acetyltransferase. 304 45

A DNase protection technique is described and applied to the interaction of three lac control proteins with supercoiled lac DNA. The technique uses end-labeled oligonucleotide primers to probe specific DNA regions as an alternative to protocols requiring restriction endonuclease cleavage or blotting. Thus DNA may be probed with high resolution in its native state. It is demonstrated that the introduction of supercoiling into DNA accelerates the rate of lac ps promoter binding by RNA polymerase but does not alter the positions at which polymerase, c-AMP-binding protein, or lac repressor bind to lac DNA.
...
PMID:Rapid "footprinting" on supercoiled DNA. 388 2

Purified preparations of RNA-dependent DNA polymerase isolated from avain myeloblastosis virus contain RNase H activity. Labeled ribohomopolymers are degraded in the presence of their complementary deoxyribopolymer, except [(3)H]poly(U).poly(dA). The degradation products formed from [(3)H]poly(A).poly(dT) were identified as oligonucleotides containing 3'-hydroxyl and 5'-phosphate termini, while AMP was not detected. The nuclease has been characterized as a processive exonuclease that requires ends of poly(A) chains for activity. Exonucleolytic attack occurs in both 5' to 3' and 3' to 5' directions.RNase H has also been purified from E. coli. This nuclease degrades all homoribopolymers tested in the presence of their complementary deoxyribopolymers to yield oligonucleotides with 5'-phosphate and 3'-hydroxyl termini. E. coli RNase H has been characterized as an endonuclease.
...
PMID:Mechanism of action of ribonuclease H isolated from avian myeloblastosis virus and Escherichia coli. 411 89

The Mn2+-dependent endonuclease activity associated with the avian myeloblastosis virus RNA-directed DNA polymerase has been shown to be activated by ATP in the presence of Mg2+. In the presence of Mn2+ the endonucleolytic activity was stimulated about 3-fold by the addition of ATP. The earlier identified Mr = 40,000 Friend murine leukemia virus (F-MuLV)-associated endonuclease which functions in the presence of both Mg2+ and Mn2+ has also been shown to be similarly stimulated by ATP. For both endonuclease activities stimulation was only observed at ATP concentrations above 0.5 mM, and it did not increase upon elevating the ATP concentration above 2.5 mM. ADP and dATP also stimulated both activities, although not to the same extent as ATP. GTP had no apparent effect and AMP seemed to inhibit both activities. The effect ATP analogs had on the F-MuLV associated endonuclease activity could suggest that the endonuclease reaction in the presence of ATP might involve the cleavage of beta-gamma phosphate bonds in ATP. Neither adenyl-5'-yl imidodiphosphate nor (beta, gamma-methylene)adenosine 5'-triphosphate stimulated the activity, whereas significant stimulation was observed in the presence of (alpha, beta-methylene)adenosine 5'-triphosphate. Although no ATPase activity could be detected in the purified F-MuLV endonuclease preparation, the data do not exclude the possibility that ATP may be cleaved in amounts which are equivalent to the number of nicks introduced into DNA by the virus-associated endonuclease. In the presence of ATP and Mg2+ the F-MuLV-associated endonuclease nicked both supercoiled and linear DNA duplexes extensively, although the former was nicked more readily than the latter. Single-stranded DNA functioned poorly as a substrate. The nicks introduced by the enzyme contained a 5'-phosphoryl terminus and a 3'-hydroxyl group.
...
PMID:Effect of ATP on the Friend Murine leukemia virus-associated endonuclease activity and the endonuclease activity of the avian myeloblastosis virus RNA-directed DNA polymerase. 616 71

One of the mediators of interferon action is an endonuclease system. This consists of (2'-5')(A)n synthetase, which, if activated by double-stranded RNA, converts ATP into (2'-5')(A)n and RNase L, a latent endoribonuclease, which binds (2'-5')(A)n and is thereby activated. We report here that a derivative of (2'-5')(A)n (i.e. (2'-5')pppApApA[32P]pCp) can be covalently cross-linked by UV irradiation to a protein in cytoplasmic extracts from mouse Ehrlich ascites tumor cells. This protein has an apparent molecular weight of 77,000 as determined by gel electrophoresis in sodium dodecyl sulfate. It appears to be identical with RNase L according to the following criteria: co-chromatography on DEAE-cellulose and Sephacryl S300. The gel filtration in Sephacryl S300 reveals that the apparent molecular weight of the protein is between 70,000 and 90,000, indicating that it is a monomer. The cross-linking is oligonucleotide specific. It is inhibited by 10 nM (2'-5')pppApApA or 1 microM (2'-5')ApApA, i.e, compounds known to block, even at low concentration, the binding of (2'-5')pppApApApCp to RNase L. (3'-5')ApApA inhibits only at a 0.1-1 mM concentration, and 1 mM ATP, 2'-AMP, or 5', 3'-pCp have no effect. (2'-5')pppApApApCp was also cross-linked to a protein with a molecular weight of about 78,000 (as determined by gel electrophoresis in sodium dodecyl sulfate) in cytoplasmic extracts from human (HeLa) cells and to protein(s) with molecular weight(s) of 75,000-77,000 (as determined by gel electrophoresis in sodium dodecyl sulfate) in nuclear extracts from Ehrlich ascites tumor cells.
...
PMID:Interferon action. Covalent linkage of (2'-5')pppApApA(32P)pCp to (2'-5')(A)n-dependent ribonucleases in cell extracts by ultraviolet irradiation. 617 33

An endodeoxyribonuclease from HeLa cells acting on apurinic/apyrimidinic (AP) sites has been purified to apparent homogeneity as judged by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The presence of Triton X-100 was necessary throughout the purification for stabilization and stimulation of activity. The endonuclease has an apparent native molecular weight of 32,000 determined by molecular sieving and an apparent subunit molecular weight of 41,000 as judged by its electrophoretic mobility in SDS-polyacrylamide gels. The activity has an absolute requirement for Mg2+ or Mn2+ and a broad pH optimum between 6.7 and 9.0 with maximal activity near pH 7.5. The enzyme has no detectable exonuclease activity, nor any endonuclease activity on untreated duplex or single-stranded DNA. It is inhibited by adenine, hypoxanthine, adenosine, AMP, ADP-ribose, and NAD+, but it is unaffected by caffeine, the pyrimidine bases, ADP, ATP, or NADH. The use of a variety of damaged DNA substrates provided no indication that the enzyme acts on other than AP sites. The enzyme appears to cleave AP DNA so as to leave deoxyribose-5-phosphate at the 5' terminus and a 3'-OH at the 3' terminus; it also removes deoxyribose-5-phosphate from AP DNA which has deoxyribose at the 3' terminus. Specific antibody has been produced in rabbits which interacts only with a 41,000-dalton protein present in the purified enzyme (presumably the enzyme itself), as well as with partially purified AP endonuclease fractions from human placenta and fibroblasts.
...
PMID:Purification and characterization of an apurinic/apyrimidinic endonuclease from HeLa cells. 625 65

An endonuclease activity associated with purified proteinase K-treated intracisternal A-particles was identified and characterized. The activity required divalent cations, preferring Mn2+ to Mg2+. Salt concentrations above 50 mM inhibited the activity. The endonuclease was greatly stimulated by ATP, ADP, and dATP, whereas AMP appeared to produce a slight inhibition. GTP had no apparent effect on the activity. The enzyme introduced single-stranded nicks into DNA and nicked preferentially supercoiled DNA duplexes in the presence of ATP, although linear duplexes also functioned as substrates. Single-stranded DNA was not nicked to any great extent. The molecular weight of the enzyme was estimated to be about 40,000. The characteristics of this enzyme are very similar to those of the endonuclease found associated with Friend murine leukemia virus.
...
PMID:Properties of an intracisternal A-particle-associated endonuclease activity which is stimulated by ATP. 627 25


<< Previous 1 2 3 4 5 Next >>

---