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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Subcellular fractionation of scrapie-infected hamster brain indicated the association of the scrapie agent with a component of the endomembrane system. Characterization by equilibrium density gradient centrifugation, electron microscopy, and marker enzymes suggested a primary association with rough and smooth endoplasmic reticulum and a possible incorporation into the plasma membrane. DNA polymerase activity demonstrated a direct correlation with regions of scrapie activity from the gradient fractions. A scrapie-related product was detected after (3H)TMP incorporation and analysis on 2.2% polyacrylamide gels. Analysis of nucleic acid species extracted from subcellular fractions resulted in a greater quantity from healthy brain; however, no qualitative distinctions were detected.
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PMID:Properties of the scrapie agent-endomembrane complex from hamster brain. 13 66

Neuronal mRNA is thought to be restricted to perikaryal and dendritic compartments containing rough endoplasmic reticulum. We have used both in situ hybridization and DNA polymerase chain reaction methods to determine the precise intracellular distribution of oxytocin mRNA. Using light- and electron-microscopic detection of in situ hybridization with 5'-bromo-2'-deoxyuridine-labeled oligonucleotide probes, we found oxytocin mRNA in axons and Herring bodies in the lateral and ventral hypothalamus, the median eminence, and the posterior lobe of the pituitary in postpartum lactating rats. Southern blot analysis of the amplification products confirmed the presence of oxytocin mRNA in all three tissue samples. The present findings indicate that oxytocin mRNA can be transported axonally. Such transport could reflect an adventitious compartmentalization or a functional storage in Herring bodies for subsequent secretion.
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PMID:mRNA coding for oxytocin is present in axons of the hypothalamo-neurohypophysial tract. 226 84

DNA polymerase alpha combined with the endoplasmic reticulum (ER) was isolated from unfertilized sea urchin eggs. NaCl treatment of this fraction released DNA polymerase alpha from the ER. The molecular size (the S value) of the ER-free DNA polymerase alpha changed with the concentration of NaCl used; being 23 S, 11-15 S and 6-8 S in the presence of 0.05-0.12 M, 0.12-0.24 M and more than 0.24 M NaCl. DNA polymerase alpha activity decreased concomitantly with the reduction in molecular size. The 6-8 S form of DNA polymerase alpha did not aggregate by itself nor with other cellular components nonspecifically, when the 23 S form was present. These results are evidence of the presence of 6-8 S DNA polymerase alpha as a high molecular weight form (23 S-form) in sea urchin eggs.
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PMID:Evidence of the existence of a high molecular weight form of DNA polymerase alpha in sea urchin eggs. 376 65

A 14-month old female Pekin duck experimentally infected as an embryo with duck hepatitis B virus via the amniotic route has been a chronic carrier of duck hepatitis B virus with very high (P/N) values of DNA polymerase activity since hatching. All the progeny were, on evaluation for congenital infection, found to be duck hepatitis B virus positive by endogenous DNA polymerase reaction and electron microscopy. These offspring remained persistently viremic throughout the study. Maternal transmission therefore bred true to a total of 49 offspring--24 ducklings (less than 24 hr old) and 25 ducks--studied. Six of these 25 ducks matched for age and sex and bled weekly for 6 weeks exhibited fluctuating plasma levels of DNA polymerase activity. Higher DNA polymerase activity was detected in newly hatched ducklings than in older viremic ducks. This observation was corroborated with the results of electron microscopic examination of thin sections of liver. Duck hepatitis B virus particles, located within vesicles of rough endoplasmic reticulum in the cytoplasm of hepatocytes, were more abundant, and therefore more readily observed, in ducklings than in older ducks.
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PMID:Maternal transmission of duck hepatitis B virus in pedigree Pekin ducks. 401 33

This communication describes the isolation and characterization of a new syncytium-forming virus of common marmosets (Callithrix jacchus jacchus). The virus, isolated from skin explants and peripheral leukocytes of healthy animals, induced syncytia and subsequent cytolysis of several human, simian, and rodent fibroblastic cultures and induced a carrier state in mixed fibroblastic-epithelial or epithelial cell lines. Cytoplasmic and nuclear viral antigen was demonstrated in infected cells by indirect immunofluorescence tests using serum obtained from persistently infected common marmosets. Abundant virus particles were detected within cisternae of endoplasmic reticulum of lytically infected cells by electron microscopy. The virus incorporated [3H]uridine, banded at a density of 1.14 to 1.16 g/cm3 in sucrose, and possessed ribonucleic acid-dependent deoxyribonucleic acid polymerase. No antigenic cross-reactivity was detected between the marmoset virus and simian foamy virus serotypes 1 to 8 in neutralization and immunofluorescence assays. A seroepidemiological survey of a marmoset colony revealed that 53.5% of common marmosets contained antibodies against the virus, whereas other species of marmosets maintained in the same colony remained free of antibodies.
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PMID:Syncytium-forming virus of common marmosets (Callithrix jacchus jacchus). 616 48

Subnuclear localization of DNA polymerase alpha was studied in sea urchin embryos. Blastula nuclei treated with EDTA and potassium phosphate released subnuclear components bearing most of the nuclear DNA polymerase alpha. These components were suggested to be a part of nuclear membrane based on their buoyant densities (1.177 and 1.136 g/cm3) in isopyknic centrifugation and the nuclear pore-like structure. Contamination with DNA and endoplasmic reticulum membrane to the subnuclear components was shown to be negligible. These results suggested that DNA polymerase alpha associates with nuclear membrane of sea urchin embryos. Nuclear membrane deprived of DNA polymerase alpha was able to associate with nuclear DNA polymerase alpha from blastulae and the cytoplasmic enzyme of unfertilized eggs efficiently, but not with the cytoplasmic enzyme of gastrulae. This result suggests that the nuclear membrane is originates from the endoplasmic reticulum with which DNA polymerase alpha associates in unfertilized eggs.
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PMID:Localization of DNA polymerase alpha on the nuclear membrane in sea urchin embryos. 622 31

There are reports in the literature that infection with hepatitis A virus in hepatitis B carriers can result in resolution of the carrier state. In an attempt to induce clearance of the carrier state of hepatitis B virus in two persistently infected chimpanzees, the chimpanzees were infused with documented non-A, non-B infectious material. Biochemical and histopathological evidence of hepatitis was accompanied by the unique abnormalities of endoplasmic reticulum associated with non-A, non-B hepatitis in the chimpanzees. Elevation of alanine aminotransferase was accompanied by fourfold reduction in one chimpanzee and sixfold reduction in the other in the plasma levels of HBV-associated DNA polymerase activity and simultaneously by twofold reduction in the concentration of hepatitis B surface antigen in both chimpanzees. A mediator may account for these changes in markers of hepatitis B virus infection, and this mechanism may also explain the occurrence of spontaneous regression in some persistently infected carriers. The significance of transient red cell anaemia in non-A, non-B hepatitis, which was observed in one of the chimpanzees, is yet to be established.
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PMID:Non-A, non-B hepatitis in persistent carriers of hepatitis B virus. 640 22

An endoplasmic reticulum nuclease which was isolated previously in this laboratory from rat liver ( Kouidou et al. (1981) Eur.J. Bioch . 120, 9-14) was found to degrade linear and circular single stranded DNA but not double stranded DNA. The DNA fragments resulting from this cleavage were longer than 20 nucleotides. In addition the nuclease was found to improve the efficiency of DNA template used by DNA polymerase I in DNA synthesis in vitro. The results were the same whether incubation of the template with the nuclease was prior to addition of DNA polymerase I or simultaneously with polymerization. When nuclease was added after the completion of polymerization by DNA polymerase I it was ineffective unless the product was denatured. These data further corroborate the observation that double stranded DNA is not cleaved by this enzyme.
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PMID:The DNase activity of an endoplasmic reticulum nuclease and its effect on DNA synthesis in vitro. 673 18

Complete and defective hepatitis B virus (HBV) particles in sera and hepatocytes were observed by electron microscopy for an understanding of the maturation process of hepatitis B virus. To distinguish Dane particles with or without DNA on the basis of staining density with uranyl acetate, Dane particles, purified from sera of asymptomatic carriers, and Dane particle cores, separated by ultracentrifugation in a metrizamide density gradient, were observed by electron microscopy. Complete cores at a low density (1.19 to 1.23 gm/cm3) were electron dense and incomplete cores at a high density (1.23 to 1.27 gm/cm3) were partially electron dense or empty. These findings demonstrated that the presence or absence of DNA is reflected by the electron density of the core. Our result, in which less than 10% serum Dane particles have full cores in ultrathin sections of the pellet, is in agreement with Gerin's finding that defective Dane particles are predominent in sera. Naked core particles and Dane particles in two biopsy specimens from patients with hepatitis B surface antigen, hepatitis B e antigen, and DNA polymerase-positive, chronic active hepatitis were classified into complete versus incomplete particles on the basis of electron density. Nine hundred and fourteen naked core particles were detected in nuclei and cytosol of 68 hepatocytes. One hundred and five core particles (11.5%) were electron dense and 809 core particles (88.5%) were partially electron dense or empty. Furthermore, 488 Dane particles were observed in the cisternae of the endoplasmic reticulum of these hepatocytes. Fifty Dane particles (10.2%) had full cores, and 438 Dane particles (89.8%) had partially full or empty cores. These findings suggest that DNA may be incorporated into about 1 to 10% of core particles when they are assembled in nuclei of hepatocytes. Morphologic differences in damage to hepatocytes containing various frequencies of full Dane particles were also studied, but no significant correlation was found between damage in hepatocytes and frequency of full Dane particles.
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PMID:Full and empty particles of hepatitis B virus in hepatocytes from patients with HBsAg-positive chronic active hepatitis. 685 94

The subcellular distribution of DNA polymerase alpha and beta was examined in unfertilized eggs and embryos of the sea-urchin, Hemicentrotus pulcherrimus. In unfertilized egg homogenates, prepared in sucrose solution containing 5 mM 2-mercaptoethanol and 5 mM MgCl2, DNA polymerases equilibrated in isospycnic centrifugation as a single peak at a buoyant density of 1.261 g/cm3 (band I). This indicates that DNA polymerases associate with a cytoplasmic organelle. Band I was converted to bands II (1.227 g/cm3), III (1.177 g/cm3) and IV (1.146 g/cm3) by EDTA treatment. The RNA content of bands I, II, III and IV was approximately 0.34, 0.25, 0.10 and 0.04 mg/mg protein respectively. In isokinetic and isopycnic centrifugations both DNA polymerase and RNA cosedimented and coequilibrated. These results suggest that bands I, II, III and IV contain various amounts of ribosomes on a common structure. Examination by electron microscopy indicated that bands I, II, III and IV contained mainly monolayered membrane vesicles with different amounts of bound ribosomes. The content of ribosomes varied in the order: band I > band II > band III > band IV. Each band contained DNA polymerase with sedimentation coefficients of 5.8-7.6 S (sensitive to N-ethylmaleimide and aphidicolin) and 3.2 S (insensitive to these drugs). We conclude that almost all of DNA polymerases alpha and beta are localized on the rough endoplasmic reticulum in unfertilized eggs. Mixing experiments suggest that the association is specific and is not an artifact of homogenization. During development of embryos DNA polymerases associated with the membrane decreased with concomitant increase in the nuclear fraction. This suggests that the enzymes migrate from the cytoplasm to the nucleus. It is discussed that the role of the endoplasmic reticulum as a storage site of DNA polymerases in unfertilized eggs and the mechanism of translocation of DNA polymerases from the cytoplasm to the nucleus during early embryogenesis.
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PMID:Association of DNA polymerase alpha and beta with rough endoplasmic reticulum in sea-urchin eggs and changes in subcellular distribution during early embryogenesis. 719 Sep 23


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