Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The E7 protein of human papillomavirus (HPV) 8 shows no in vitro transforming activity, in contrast to E7 of the genital HPVs, but seems to be involved in the control of viral DNA replication. To determine whether functional differences between the E7 proteins of HPV16 and HPV8 were reflected in differences in their biochemical properties, we characterized the E7 protein of HPV8 expressed from the late simian virus 40 promoter in COS 7 cells. An E7-specific antiserum was obtained by immunizing rabbits with a beta-gal-E7 fusion protein containing all of the E7 polypeptide. This antiserum specifically precipitated from [35S]cysteine but not from 32PO4-labeled transiently transfected COS 7 cells a protein with a low mobility of 17 kDa in SDS-PAGE. The high sedimentation rate in nondenaturing glycerol gradients pointed to an interaction with other proteins or to the existence of E7 oligomers. An association with the retinoblastoma protein could, however, be excluded. The 5' ends of HPV8 transcripts derived from the E6-E7 region in G418 selected rodent cells, which were mapped by nuclease S1 digestion, are located upstream of ORFs E6 and E7, respectively. No evidence for an E6*I-like mRNA was found. In COS 7 cells transfected with a plasmid expressing the E6-E7 region of HPV8 under the control of the late SV40 promoter, however, the E7 protein was translated from a polycistronic mRNA potentially encoding E6 and E7. These data indicate that the E7 protein of HPV8 may be expressed in two ways: (i) through translation of an E7-specific mRNA, as with HPV6 and HPV11, or (ii) through internal initiation of translation at the ATG of E7.
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PMID:The E7 protein of human papillomavirus 8 is a nonphosphorylated protein of 17 kDa and can be generated by two different mechanisms. 217 Dec 14

We studied the expression of the core region of the hepatitis B virus genome in mammalian cells with recombinant plasmid vectors. Stably transformed rat fibroblast cell lines were established by transfection with vectors containing subgenomic and genome-length hepatitis B virus DNA, followed by G418 selection. The RNA transcripts directed by the core region were characterized by Northern blot hybridization and S1 nuclease mapping. Using the chloramphenicol acetyltransferase gene expression system, the promoter activity located upstream of the core open reading frame was confirmed. The synthesis of core and e polypeptides was studied with a commercial radioimmunoassay. These studies show that partial deletion of the precore sequences abolished secretion of the e antigen, but there was pronounced synthesis of the core antigen in transfected cells.
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PMID:Expression of hepatitis B viral core region in mammalian cells. 243 Dec 77

A series of recombinant plasmid vectors containing hepatitis B virus (HBV) DNA sequences was constructed to study the biosynthesis of the hepatitis B virus surface antigen (HBsAg) RNA and to locate transcriptional control elements involved in the regulation of the S and pre-S DNA sequences. We examined the transcription of the HBsAg gene in permanent cell lines that were developed by transfecting with recombinant vectors containing HBV sequences and the neomycin gene followed by G418 selection. We further defined the promoter activities upstream of and within the pre-S sequences using the assayable chloramphenicol acetyltransferase gene. Results obtained from S1 nuclease digestion and primer extension suggest that HBsAg transcripts are initiated at multiple sites in the pre-S region and from a site upstream of the pre-S region. Chloramphenicol acetyltransferase assays indicate that DNA sequences within and upstream of the pre-S region contain promoter activities and that the "TATA" sequence-containing promoter and the internal promoter show similar levels of activities in CV-1 cells and several other cell lines tested.
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PMID:Transcriptional control elements of hepatitis B surface antigen gene. 345 53