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

A region of the Reticuloendotheliosis virus (REV) long terminal repeat (LTR) harbouring single or duplicated copies of 46-bp and 26-bp sequence elements is implicated in enhancer activity. Sequences residing upstream from the proviral 3' LTR did not contribute to activity of the intact LTR. Gene expression regulated by a combination of REV enhancer and SV40 early region promoter was 50-fold less than from the analogous construct containing the chicken syncytial virus promoter. Deletion of LTR sequences immediately downstream of the CAP site, which include a region capable of forming a stable hairpin in the mRNA, decreased expression by 70%. Expression assays and S1 nuclease mapping showed that a second transcriptional start site, identified by transcription in vitro using HeLa cell lysates and purified DNA templates, was not used in vivo in the cell lines examined.
 ...
PMID:Transient expression analysis of the reticuloendotheliosis virus long terminal repeat element. 254 93

Chicken syncytial virus, a member of the reticuloendotheliosis virus family, induces B-cell lymphomas in chickens that arise by transcriptional activation of the chicken c-myc gene. In vitro transcription studies on cloned tumor DNA containing a deleted chicken syncytial virus provirus integrated upstream from, and in the same transcriptional orientation as, the chicken c-myc coding region were utilized to map possible transcriptional promoters and initiation sites. In vitro transcripts extending into c-myc sequences were initiated at two sites within the downstream long terminal repeat (LTR) closest to c-myc coding sequences. Both initiation sites have been precisely mapped by S1 nuclease and DNA sequencing methods. One site (I1) lies at the U3-R junction of the LTR, and the other site (I2) lies approximately 160 nucleotides upstream. Transcriptional control signals, including TATA- and CAAT-like sequences are present at appropriate distances upstream from the initiation sites. Both initiation sites are utilized to a similar extent. The upstream chicken syncytial virus LTR was also shown to be transcriptionally active in vitro. Two strong transcriptional initiation sites were also found in the LTR of spleen necrosis virus, a related member of the reticuloendotheliosis virus family; therefore, it seems likely that the existence of two transcriptional initiation sites is a common feature of the reticuloendotheliosis virus LTR, in contrast to other previously studied retroviral LTRs that exhibit one such site. The possible implications of these findings are discussed.
 ...
PMID:In vitro transcription analysis of the viral promoter involved in c-myc activation in chicken B lymphomas: detection and mapping of two RNA initiation sites within the reticuloendotheliosis virus long terminal repeat. 298 11