Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report on the discovery and isolation of DNA- and RNA-containing macromolecular nuclear complexes whose purified major DNA possessed electrophoretic mobilities of approximately 90 and approximately 25 kbp. The deoxyribonucleoprotein-ribonucleoprotein complexes contain RNA and DNA polymerase and primase activities and were isolated from nuclei of murine RAW117 large-cell lymphoma cells by restriction digestion with Msp-I, gentle extraction with solutions containing MgCl2, but without chelating agents, and low ionic strength gel electrophoresis. Two-dimensional (isoelectric focusing/M(r)) gel electrophoresis and silver staining of the proteins of the complexes after treatment with DNase I indicated the presence of approximately 30 protein components. In vitro DNA and RNA polymerase/primase assays showed that the DNP/RNP complexes had very high enzyme specific activities. Using the DNP/RNP complexes a discrete DNA polymerase alpha product of approximately 85 kbp was synthesized that was not synthesized in the presence of the DNA polymerase alpha inhibitor aphidicolin. RNA polymerase assays in the presence of excess alpha-amanitin indicated that the complexes possessed significant RNA polymerase I activity. Preparing the complexes at various times after the release of cells from a double thymidine block showed the complexes as well as the complex-associated enzyme activities to be cell-cycle dependent. The DNA and RNA polymerase-related activities were highest in late S phase, 7 and 9 h, respectively, after release from the double thymidine block. The complexes synthesized a specific in vitro DNA polymerase product using endogenous substrate and nucleotide precursors.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nucleoprotein complexes released from lymphoma nuclei that contain the abl oncogene and RNA and DNA polymerase and RNA primase activities. 142 73

Eukaryotic chromosomes end with tandem repeats of simple sequences. These GC rich repeats allow telomere replication and stabilize chromosome ends. Telomere replication involves an equilibrium of sequence loss and addition at the ends of chromosomes. Repeats are added de novo by telomerase, an unusual DNA polymerase. Telomerase is an RNP in which an essential RNA component provides the template for the added telomere repeats. Telomere length maintenance plays an essential role in cell viability.
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PMID:Telomeres, telomerase and senescence. 224 33

The concentrations of the Sm, RNP, La and Ro antigens of thymus glands from rats were determined depending on the developmental stage of the animals. It was found that lupus antigens strongly decrease after birth. Parallel with this change, the activities of the enzymes DNA polymerase alpha and terminal nucleotidyl transferase in the thymus glands drop during maturation and ageing. These biochemical analyses were supported by immunofluorescence studies using human thymus glands. Moreover, it is documented that a redistribution of Sm and Ro occurs during development. Focusing on Sm, fetal thymus glands contain this antigen predominantly in the cytoplasm, while in immature, mature or old animals Sm is found almost exclusively in the nucleus. From these data we conclude that the amounts of the lupus antigens are additional parameters for the age-correlated function of thymocytes.
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PMID:Age-correlated changes in the lupus erythematosus antigens Ro, La, Sm and RNP of the thymus gland. 333 Jun 89

MSSP has been identified as a protein that binds to both single- and double-stranded sequences of a putative DNA replication origin sequence in the human c-myc gene. MSSP possesses versatile functions, including stimulation of DNA replication, transcriptional regulation, apoptosis induction, and cell transformation coordinated by c-Myc. MSSP contains two RNP domains, RNP1-A and RNP1-B, both of which are necessary for all of the functions of MSSP. In this study, we found that MSSP binds to the N-terminal region of a catalytic subunit of a human DNA polymerase alpha via its RNP domains both in vitro and in human cells. Furthermore, MSSP was released from the putative DNA replication origin of the c-myc gene after it complexed with DNA polymerase alpha, and MSSP stimulated DNA polymerase activity in vitro.
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PMID:MSSP, a protein binding to an origin of replication in the c-myc gene, interacts with a catalytic subunit of DNA polymerase alpha and stimulates its polymerase activity. 1086 58

The fine binding characteristics of three well-characterized human autoantibodies B3, RH14 (anti-DNA) and UK4 (anti-cardiolipin) in their IgG and cloned Fab formats, were investigated. Although in severe combined immunodeficiency (SCID) mice B3 and RH14 both induce proteinuria, only RH14 induces early features of lupus nephritis, whereas UK4 exhibits lupus anticoagulant activity. RH14 exhibited up to 10 fold higher binding to DNA compared to that shown by B3 or UK4 and involved significant electrostatic and phosphate group interactions. Only RH14 exhibited strong anti-Sm cross-reactivity residing on the C-terminus of the antigen as determined by the use of 76 overlapping 15mer peptides. Chain shuffling experiments indicate that anti-Sm/RNP and anti-Jo-1 activities of B3 and UK4 co-exist on one of the two chains (light, B3; heavy, UK4). The present study provides evidence that a human anti-DNA antibody can also be an anti-ENA antibody. Furthermore, the anti-DNA antibodies also exhibited cross-reactivity against glutathione-S-transferase and DNA polymerase PolIV of bacterial origin. This is the first demonstration of the presence of such cross-reactivities on lupus anti-DNA antibodies. We now demonstrate that subsets of sera from the patients with lupus, recognise these antigens. This observation may in some cases provide a mechanism for the common expression of a variety of autoantibodies observed in systemic lupus erythematosus (SLE).
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PMID:Fine binding characteristics of human autoantibodies-partial molecular characterization. 1518 28

Mobile group II introns retrohome by an RNP-based mechanism in which the intron RNA reverse splices into a DNA site and is reverse transcribed by the associated intron-encoded protein. The resulting intron cDNA is then integrated into the genome by cellular mechanisms that have remained unclear. Here, we used an Escherichia coli genetic screen and Taqman qPCR assay that mitigate indirect effects to identify host factors that function in retrohoming. We then analyzed mutants identified in these and previous genetic screens by using a new biochemical assay that combines group II intron RNPs with cellular extracts to reconstitute the complete retrohoming reaction in vitro. The genetic and biochemical analyses indicate a retrohoming pathway involving degradation of the intron RNA template by a host RNase H and second-strand DNA synthesis by the host replicative DNA polymerase. Our results reveal ATP-dependent steps in both cDNA and second-strand synthesis and a surprising role for replication restart proteins in initiating second-strand synthesis in the absence of DNA replication. We also find an unsuspected requirement for host factors in initiating reverse transcription and a new RNA degradation pathway that suppresses retrohoming. Key features of the retrohoming mechanism may be used by human LINEs and other non-LTR-retrotransposons, which are related evolutionarily to mobile group II introns. Our findings highlight a new role for replication restart proteins, which function not only to repair DNA damage caused by mobile element insertion, but have also been co-opted to become an integral part of the group II intron retrohoming mechanism.
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PMID:Genetic and biochemical assays reveal a key role for replication restart proteins in group II intron retrohoming. 2363 34

LINE-1 (L1) retrotransposons are repetitive elements in mammalian genomes. They are capable of synthesizing DNA on their own RNA templates by harnessing reverse transcriptase (RT) that they encode. Abundantly expressed full-length L1s and their RT are found to globally influence gene expression profiles, differentiation state, and proliferation capacity of early embryos and many types of cancer, albeit by yet unknown mechanisms. They are essential for the progression of early development and the establishment of a cancer-related undifferentiated state. This raises important questions regarding the functional significance of L1 RT in these cell systems. Massive nuclear L1-linked reverse transcription has been shown to occur in mouse zygotes and two-cell embryos, and this phenomenon is purported to be DNA replication independent. This review argues against this claim with the goal of understanding the nature of this phenomenon and the role of L1 RT in early embryos and cancers. Available L1 data are revisited and integrated with relevant findings accumulated in the fields of replication timing, chromatin organization, and epigenetics, bringing together evidence that strongly supports two new concepts. First, noncanonical replication of a portion of genomic full-length L1s by means of L1 RNP-driven reverse transcription is proposed to co-exist with DNA polymerase-dependent replication of the rest of the genome during the same round of DNA replication in embryonic and cancer cell systems. Second, the role of this mechanism is thought to be epigenetic; it might promote transcriptional competence of neighboring genes linked to undifferentiated states through the prevention of tethering of involved L1s to the nuclear periphery. From the standpoint of these concepts, several hitherto inexplicable phenomena can be explained. Testing methods for the model are proposed.
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PMID:LINEs of evidence: noncanonical DNA replication as an epigenetic determinant. 2403 80