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)

The 145-kDa molecule that has been identified as the C3d receptor CR2 was isolated from lysates of Raji cells by affinity chromatography by using the monoclonal antibody (MoAb)HB-5. The purified protein was incorporated into 14C-phosphatidylcholine liposomes by deoxycholate dialysis followed by flotation on discontinuous sucrose gradients. Incorporation of the receptor was verified by testing the gradient fractions for CR2 by an enzyme-linked immunosorbent assay. Liposomes were shown to be unilamellar vesicles ranging in diameter from 25 to 100 nm by electron microscopy. The external orientation of CR2 in the membranes was demonstrated by immunoelectron microscopy. The functional activities of liposomes containing CR2 and liposomes without protein were compared. CR2 liposomes bound to EC3d, but not to E, and this binding was inhibited by the anti-CR2 MoAb OKB7 and by a MoAb specific for C3d. Control liposomes failed to bind to either E or EC3d. The ability of CR2 to function as a receptor for Epstein Barr virus (EBV) was tested in two ways. First, CR2 liposomes bound to B95-8, a cell line expressing EBV membrane antigens, but not to B95-8 cells treated with the viral DNA polymerase inhibitor phosphonoformic acid. Second, liposomes containing CR2 were shown by ultracentrifugal analyses to bind directly to purified EBV, and this binding was also inhibited by OKB7. Control liposomes did not bind to B95-8 cells or to EBV. These findings show that CR2 purified from detergent extracts of Raji cells can be reconstituted into lipid membranes with maintenance of its dual functions as a receptor for C3d and EBV.
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PMID:Incorporation of the purified Epstein Barr virus/C3d receptor (CR2) into liposomes and demonstration of its dual ligand binding functions. 300 15

NPC-KT cl.S61, a subclone derived from an epithelial-nasopharyngeal carcinoma hybrid cell line NPC-KT, showed extensive Epstein-Barr virus (EBV) production and cell fusion when the EBV replicative cycle was induced by 5-iodo-2'-deoxyuridine. On the contrary, parental NPC-KT cells produced virus at a lower level and did not show cell fusion. Cell fusion in cl.S61 cells was blocked by 2-deoxyglucose and acyclovir, inhibitors of glycosylation and EBV DNA polymerase, respectively, with a concomitant decrease in the number of cells expressing EBV growth-associated antigens. However, the frequency of virus antigen expression in parental NPC-KT cells was not significantly affected by these drugs. This result suggests that efficient production of EBV from cl.S61 cells is due to the spreading of viral replicative cycle via cell fusion. It was also demonstrated by in situ autoradiography that cl.S61 cells producing virus fused to not only EBV receptor/CR2 positive Raji and BJAB cells, but also to receptor-negative Jurkat cells. The possible mechanism of EBV entry into cells devoid of virus receptor by cell fusion is discussed.
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PMID:Epstein-Barr virus lytic cycle spreads via cell fusion in a nasopharyngeal carcinoma hybrid cell line. 829 64

CDP/Cux (CCAAT-displacement protein/cut homeobox) contains four DNA binding domains, namely, three Cut repeats (CR1, CR2, and CR3) and a Cut homeodomain. CCAAT-displacement activity involves rapid but transient interaction with DNA. More stable DNA binding activity is up-regulated at the G(1)/S transition and was previously shown to involve an N-terminally truncated isoform, CDP/Cux p110, that is generated by proteolytic processing. CDP/Cux has been previously characterized as a transcriptional repressor. However, here we show that expression of reporter plasmids containing promoter sequences from the human DNA polymerase alpha (pol alpha), CAD, and cyclin A genes is stimulated in cotransfections with N-terminally truncated CDP/Cux proteins but not with full-length CDP/Cux. Moreover, expression of the endogenous DNA pol alpha gene was stimulated following the infection of cells with a retrovirus expressing a truncated CDP/Cux protein. Chromatin immunoprecipitation (ChIP) assays revealed that CDP/Cux was associated with the DNA pol alpha gene promoter specifically in the S phase. Using linker scanning analyses, in vitro DNA binding, and ChIP assays, we established a correlation between binding of CDP/Cux to the DNA pol alpha promoter and the stimulation of gene expression. Although we cannot exclude the possibility that stimulation of gene expression by CDP/Cux involved the repression of a repressor, our data support the notion that CDP/Cux participates in transcriptional activation. Notwithstanding its mechanism of action, these results establish CDP/Cux as an important transcriptional regulator in the S phase.
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PMID:CDP/Cux stimulates transcription from the DNA polymerase alpha gene promoter. 1266 98