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 organization of alpha globin genes in normal human DNA was examined by restriction endonuclease mapping, alpha globin-specific fragments in endonuclease digests of total cell DNA were identified after electrophoresis by hybridization with [32P]cDNA following the blotting procedure of Southern [(1975) J. Mol. Biol. 98, 503--517]. The data provide direct evidence for the duplication of alpha genes and further indicate that these loci are closely linked within a single restriction fragment. The HindIII sites (codons 90/91) of these duplicated genes lie approximately 3.7 kilobases apart in the physical map proposed for this region. This organization of alpha genes can be altered in DNA of individuals with alpha-thalassemia.
Proc Natl Acad Sci U S A 1978 Dec
PMID:The duplicated human alpha globin genes lie close together in cellular DNA. 28 16

Inverted repeat DNA sequences of Caulobacter crescentus have been isolated, characterized, and cloned in a bacteriophage lambda vector. Both whole populations and individual clones of these sequences were hybridized to restriction endonuclease-generated fragments of chromosomal DNA isolated from cells that were in different stages of the cell cycle. Some inverted repeat DNA sequences were observed to hybridize to different regions of the chromosomal DNA isolated from the morphologically and biochemically distinct swarmer cell and stalked cell populations. These results suggest that the inverted repeat sequences have the capacity to rearrange and thus be located at different sites on the genomes of the different cell types.
Proc Natl Acad Sci U S A 1979 Dec
PMID:Cell-cycle-associated rearrangement of inverted repeat DNA sequences. 29 18

Restriction endonuclease assay of mitochondria DNA (mtDNA) and standard starch-gel electrophoresis of proteins encoded by nuclear genes have been used to analyze phylogenetic relatedness among a large number of pocket gophers (Geomys pinetis) collected throughout the range of the species. The restriction analysis clearly distinguishes two populations within the species, an eastern and a western form, which differ by at least 3% in mtDNA sequence. Qualitative comparisons of the restriction phenotypes can also be used to identify mtDNA "clones" within each form. The mtDNA clones interconnect in a phylogenetic network which represents an estimate of matriarchal phylogeny for G. pinetis. Although the protein electrophoretic data also differentiate the eastern and western forms, the data are of limited usefulness in establishing relationships among more local subpopulations. The comparison between these two data sets suggests that restriction analysis of mtDNA is probably unequalled by other techniques currently available for determining phylogenetic relationships among conspecific organisms.
Proc Natl Acad Sci U S A 1979 Dec
PMID:Mitochondrial DNA clones and matriarchal phylogeny within and among geographic populations of the pocket gopher, Geomys pinetis. 29 56

Induction and repair of DNA breaks following irradiation with NIRS cyclotron neutrons were studied in cultured mammalian cells (L5178Y) in comparison to those following gamma-rays. The yield of the total single-strand breaks, 3'OH terminals and sites susceptible to S1 endonuclease following fast neutrons was found to be approximately 50 per cent of that following gamma-irradiation. On the other hand, the yield of double-strand breaks was slightly higher after fast neutrons than after gamma-rays. The percentage of the total single-strand breaks remaining unrejoined at 3 hours after post-irradiation incubation was found to be distinctly higher after the fast neutrons than after gamma-rays. The neutron-induced damage appears to carry a higher proportion of alkali-labile lesions compared to gamma-rays. It was concluded that the increase in the yield of double-strand breaks and of unrejoinable breaks is responsible for a high r.b.e. of the cyclotron neutrons.
Int J Radiat Biol Relat Stud Phys Chem Med 1979 Dec
PMID:Induction and repair of DNA strand breaks in cultured mammalian cells following fast neutron irradiation. 31 55

One of the eight endonuclease EcoRI fragments of yeast DNA that hybridize to yeast tRNATyr has been identified with the genetically defined nonsense-suppressor locus SUP4. This identification was achieved by analyzing the meiotic linkage between the genetic determinant for the SUP4 phenotype and that for an electrophoretic variant of the EcoRI fragment. The SUP4 gene was then cloned from an ochre-suppressing yeast strain and analyzed by DNA sequencing. A wild-type SUP4 gene and two other genetically unidentified tRNATyr genes were also sequenced. The sequence of the ochre suppressor differs from that of the wild-type genes by virtue of a G.C leads to T.A transversion in the base pair that codes for the wobble position base of the tRNATyr anticodon. All four genes contain, immediately to the 3' side of the anticodon triplet, a 14 base pair tract that is not present in mature tRNATyr. Although the four genes, which represent three unlinked chromosomal loci, all encode the same mature tRNA sequence, there is virtually no observable sequence homology between the three loci in the region preceding the 5' end of the mature tRNATyr sequences.
Proc Natl Acad Sci U S A 1977 Dec
PMID:Nucleotide sequence of a mutant eukaryotic gene: the yeast tyrosine-inserting ochre suppressor SUP4-o. 34 Nov 57

A plaque-forming lambdapolA phage was isolated from a population of transducing phage made in vitro from Escherichia coli DNA and a phage vector digested with restriction endonuclease HindIII. Amber mutations, in genes whose products are necessary for late protein synthesis (Q) and cell lysis (S), were crossed into the lambdapolA phage. Infection of either polA+ or polA- bacteria with this phage, under conditions permitting DNA replication but preventing phage production and lysis, elevated the levels of DNA polymerase I to between 75- and 100-fold that detected in a wild-type strain. The kinetics of enzyme production suggest that the polA gene is transcribed from its own promoter rather than from any of the well-characterized phage promoters. The fragment of E. coli DNA within the lambdapolA phage comprises approximately 5000 base pairs, sufficient to accommodate the polA gene and one, or two, coding sequences for smaller proteins.
Proc Natl Acad Sci U S A 1977 Dec
PMID:Isolation and characterization of a lambdapolA transducing phage. 34 Nov 64

A precise genetic-physical map of the tna-ilv region at 82 min on the genetic map of E. coli is obtained through deletion mapping and analysis by restriction endonuclease EcoRI of plasmids, derived from an F' carrying the genes between aroE and ilv. A locus, designated het, which in its diploid state results in slow growth and heterogeneity of cell size due to distorted cell division, maps between bglB and asn, 30-45 kb counterclockwise of ilv. The pattern of R.EcoRI cleavage sites in the het region is identical with the pattern obtained by Marsh and Worcel (1977) who analyzed DNA labeled preferentially in the region of the DNA replication origin (oriC). We suggest that oriC is identical with the het site and that it can be allocated to a position 32 kb counterclockwise of the ilv operon.
Mol Gen Genet 1977 Dec 14
PMID:Origin of replication, oriC, of the Escherichia coli chromosome: mapping of genes relative to R.EcoRI cleavage sites in the oriC region. 34 4

Recent work from several laboratories has established the following points about the synthesis of the polypeptide chain elongation factors Tu and G in Escherichia coli. (i) Elongation factor Tu is the product of duplicate, highly conserved genes, tufA and tufB, which are widely separate parts of the chromosome. (ii) The molar concentration of this factor is considerably higher than that of elongation factor G which is encoded by the fus gene. (iii) Although the tufA and fus genes are close together and can be co-transcribed in the direction from fus to tufA, the tufA gene product is synthesized at several times the rate of the fus gene product. In an attempt to understand what mechanism(s) could account for the differential expression of the tufA and fus genes, we sought to obtain more precise information on the physical relationship of these genes. By examining heteroduplexes between restriction endonuclease-generated fragments of DNA containing the tufA, fus, and tufB genes, we have demonstrated that the fus and tufA genes are intimately related physically in one of two possible arrangements. Either the NH2-terminal region of the tufA gene is contiguous with the COOH-terminal region of the fus gene or the beginning of the tufA gene overlaps part of the fus gene. These results mean that if the tufA gene is always co-transcribed with the fus gene, then some mechanism must allow the tufA portion of the transcript to be translated more often than the fus gene portion of the transcript.
J Biol Chem 1978 Dec 10
PMID:The peptide chain elongation factor genes tufA and fus of Escherichia coli are intimately related physically. 36 40

A phage-plasmid hybrid was constructed for use as a recombinant DNA vector, allowing the propagation of cloned EcoRI restriction endonuclease fragments of about 2 X 10(6) to 11 X 10(6) daltons. The colicin E1 plasmid replicon was fused to the left arm of a lambdagt generalized transducing phage with a thermolabile repressor, yielding a genome which could be replicated either by phage lambda functions or via the colicin E1 plasmid replicon. At the nonpermissive temperature, phage functions were derepressed and phage growth occurred lytically. Alternatively, at the permissive temperature, lambda functions were repressed and the vector replicated as a covalently closed circular plasmid. The phage-plasmid hybrid vector could be maintained at a copy number determined by the colicin E1 plasmid replicon and was also sensitive to amplification after chloramphenicol treatment. An EcoRI fragment of Escherichia coli DNA encoding genes of the arabinose operon also was inserted into the central portion of the vector.
J Bacteriol 1978 Dec
PMID:Construction of a hybrid bacteriophage-plasmid recombinant DNA vector. 36 94

We have made use of lysogens of a specialized transducing bacteriophage, lambdapyrG+ relA+, to select nonsense (relAnon) and insertion (relAins) mutations in the relA gene. Three independent relAnon mutants were isolated on the phage. In all three, the relaxed phenotype was suppressed by supD, supE, supF or sup6. Three independent relAins mutants were isolated, all containing an insertion element (probably IS2) in an apparently identical location in the relA gene. Polyacrylamide gel electrophoretic analysis of peptides synthesized by the phages in ultraviolet lightkilled host cells revealed that no stringent factor was coded for by either the relAins or relAnon phages (the latter in a sup+ cell); stringent factor was detected when the relAnon phages were used in a similar experiment with supD or supE host cells. The relAnon and relAins mutations could be crossed in haploid form in the E. coli chromosome. These recombinants grew with a normal doubling time, had a ppGpp pool which was between 70 and 100% compared with the classical relA strain, and underwent a normal carbon source shift-down. A restriction endonuclease map of the pyrG relA region of the specialized transducing phage is presented in which the position of the insertion element (recognized by a novel Hind III-cut site) defines the position of the relA gene. This position was verified by an analysis of the structure of five plasmids formed by cloning portions of the region in the pBR322 cloning vehicle. Our results indicate that the relA gene is not an essential cellular function, that there might be a second mechanism for the synthesis of basal level ppGpp in the cell and that the sole function of the relA gene is apparently the high level ppGpp synthesis triggered in response to deacylated tRNA.
Cell 1978 Dec
PMID:Nonsense and insertion mutants in the relA gene of E. coli: cloning relA. 36 54


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