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At least 127 records · Page 7Linked to original sources
PubMed1997

Inhibition of HIV type 1 RNA dimerization by antisense DNA corresponding to the 17-nucleotide sequence downstream from the splice donor site of HIV type 1 RNA.

HIV-1 RNA dimerization involves at least two key regions, one located upstream from the splice donor (SD) site, and the other located downstream from the SD site. To determine the precise location and the mechanism of action of the downstream region, we constructed a model system using a synthetic HIV-1 RNA fragment (HXB2, 455-1146), which dimerized at relatively low salt concentrations (100 mM KCl, 1 mM MgCl2). We tested in this system antisense DNAs that are complementary to both the upstream and downstream regions of HIV-1 RNA for their possible inhibitory effects on dimerization. Antisense DNAs complementary to nucleotides 773-789 located downstream from the SD site effectively inhibited dimerization of HIV-1 RNA. These inhibitory antisense DNAs hybridized with the dimer form of HIV-1 RNA, and dissociated the dimer into monomers. However, antisense DNAs complementary to the region upstream from the SD site did not hybridize with the dimer, although they inhibited RNA dimerization and also dissociated the preformed dimer.

Base Sequence↗
PubMed1988

Intron sequences and the length of the downstream second exon affect the binding of hnRNP C proteins in an in vitro splicing reaction.

The proteins that are in direct contact with the pre-mRNA in an in vitro splicing reaction were analyzed by UV cross-linking experiments. Six major proteins (120, 55, 44, 42, 39 and 38 KD) and three minor polypeptides (84, 72 and 63 KD) were detected. The predominant proteins 44, 42 KD belong to the class of hnRNP C proteins since they were immunoprecipitated by monoclonal antibodies directed against hnRNP C proteins. The cross-linked proteins were not detected in the absence of Mg2+, ATP or when RNA lacking introns were used as substrates in the splicing reactions. The effect of exon sequences on the binding efficiency for the photocrosslinked proteins was investigated. Transcripts containing a second exon of 24 nucleotides for the beta-globin or 107 nucleotides for the mouse insulin, yielded a reduced amount of cross-linked proteins when compared with "full length" pre-mRNAs. Sequences within the first exon of the beta-globin pre-mRNA did not affect the binding efficiency of these proteins. The reduced binding efficiency of the cross-linked proteins for the truncated beta-globin or mouse insulin pre-mRNAs correlated with the lower efficiency for in vitro splicing. Substitutions with unrelated sequences in the beta-globin second exon restore the binding of the cross-linked proteins indicating that the length of the second exon and not specific sequences are relevant for the binding efficiency of these proteins. The SP6/mouse insulin oligonucleotides cross-linked to the hnRNP C proteins were isolated and sequenced. A 17-mer was located in the second exon (134 nucleotides downstream from the 3' splice site) and a 14-mer in the intron region (25 nucleotides downstream the 5' splice site). The beta-globin oligonucleotides cross-linked to the hnRNP C proteins were a 13-mer in the second exon (28 nucleotides downstream the 3' splice site) and an 8-mer in the first exon (81 nucleotides downstream the 5' end of the pre-mRNA). Our results indicate that the hnRNP C proteins interact with those oligonucleotides located in different regions of the pre-mRNA. The binding efficiency of those proteins, however, depends on the length of the second exon and the presence of intron sequences (secondary and/or tertiary pre-mRNA structure).

Adenosine Triphosphate↗
PubMed1996

Relationship between plus strand DNA synthesis removal of downstream segments of RNA by human immunodeficiency virus, murine leukemia virus and avian myeloblastoma virus reverse transcriptases.

During retroviral reverse transcription the genomic RNA is degraded by the RNase H activity of reverse transcriptase (RT). Previous results suggest that after RNA-directed DNA synthesis, fragments of RNA remain annealed to the newly synthesized DNA [DeStefano et al.(1991) J. Biol.Chem. 266, 7423-7431]. These must be removed to allow synthesis of the second DNA strand. We measured the ability of HIV-, AMV- and MuLV-RT to coordinate DNA-dependent DNA synthesis and removal of downstream segments of RNA. The substrates employed were DNA templates having upstream DNA and downstream RNA primers. We found that none of the wild type RTs elongated the upstream DNA without simultaneous degradation of the RNA. Consistent with these results, HIV-, AMV- and MuLV-RT showed relatively higher affinity for RNA than for DNA oligonucleotides bound to a DNA template. Differences were observed in the RNA degradation and DNA extension patterns generated by the different RTs. AMV-RT degraded the RNA to segments 11-12 nt long, and readily elongated the upstream DNA to the end of the template. MuLV- and HIV-RT degraded the RNA primarily to segments 15-16 nt long. At low concentrations of the latter two RTs, the DNA primer stalled when it encountered the 5'-end of the RNA. In sufficient excess, all of the RTs elongated the upstream primer without stalling. Even though we were unable to detect displacement of the downstream RNA by the wild type RTs, MuLV- and HIV-RT lacking RNase H, were able to elongate the upstream DNA to the end of the template without degradation of the RNA. This suggests that degradation of downstream pieces of RNA is not absolutely required before synthesis of the plus strand DNA. The implications of these findings for viral replication are discussed.

Animals↗
PubMed2000

The efficiency of Escherichia coli selenocysteine insertion is influenced by the immediate downstream nucleotide.

Selenocysteine (Sec) incorporation requires the TGA opal codon and a downstream Sec insertion sequence (SECIS), which can be partially randomized and cloned into M13 pIII fusion constructs for phage display. This combinatorial approach provides a convenient non-radioactive assay that couples phage production to opal suppression. Two SECIS libraries were prepared, with the immediate downstream nucleotide either randomized (TGAN) or fixed as thymidine (TGAT). The TGAN library resulted in a majority of clones with a downstream purine and selenium-independent phage production, implicating the endo-genous tryptophan-inserting opal suppression pathway. Although the addition of sodium selenite to the growth medium did not affect phage production, it did increase the level of Sec insertion, as shown by the chemical reactivity of the resulting phage. The TGAT phage library yielded clones with strictly selenium-dependent phage production and reactivity consistent with the presence of Sec. These clones were prone to spontaneous mutation upon further propagation, however, resulting in loss of the selenium-dependent phenotype. We conclude that the immediate downstream nucleotide determines whether the endogenous opal suppression pathway competes with co-translational Sec insertion.

ATP-Binding Cassette Transporters↗
PubMed2001

Complementarity of the 16S rRNA penultimate stem with sequences downstream of the AUG destabilizes the plastid mRNAs.

Escherichia coli mRNA translation is facilitated by sequences upstream and downstream of the initiation codon, called Shine-Dalgarno (SD) and downstream box (DB) sequences, respectively. In E.coli enhancing the complementarity between the DB sequences and the 16S rRNA penultimate stem resulted in increased protein accumulation without a significant affect on mRNA stability. The objective of this study was to test whether enhancing the complementarity of plastid mRNAs downstream of the AUG (downstream sequence or DS) with the 16S rRNA penultimate stem (anti-DS or ADS region) enhances protein accumulation. The test system was the tobacco plastid rRNA operon promoter fused with the E.coli phage T7 gene 10 (T7g10) 5'-untranslated region (5'-UTR) and DB region. Translation efficiency was tested by measuring neomycin phosphotransferase (NPTII) accumulation in tobacco chloroplasts. We report here that the phage T7g10 5'-UTR and DB region promotes accumulation of NPTII up to approximately 16% of total soluble leaf protein (TSP). Enhanced mRNA stability and an improved NPTII yield ( approximately 23% of TSP) was obtained from a construct in which the T7g10 5'-UTR was linked with the NPTII coding region via a NheI site. However, replacing the T7g10 DB region with the plastid DS sequence reduced NPTII and mRNA levels to 0.16 and 28%, respectively. Reduced NPTII accumulation is in part due to accelerated mRNA turnover.

Bacteriophage T7↗
PubMed2002

Downstream sequence elements with different affinities for the hnRNP H/H' protein influence the processing efficiency of mammalian polyadenylation signals.

Auxiliary factors likely play an important role in determining the polyadenylation efficiency of mammalian pre-mRNAs. We previously identified an auxiliary factor, hnRNP H/H', which stimulates 3'-end processing through an interaction with sequences downstream of the core elements of the SV40 late polyadenylation signal. Using in vitro reconstitution assays we have demonstrated that hnRNP H/H' can stimulate processing of two additional model polyadenylation signals by binding at similar relative downstream locations but with significantly different affinities. A short tract of G residues was determined to be a common property of all three hnRNP H/H' binding sites. A survey of mammalian polyadenylation signals identified potential G-rich hnRNP H/H' binding sites at similar downstream locations in approximately 34% of these signals. All of the novel G-rich elements tested were found to bind hnRNP H/H' protein and the processing of selected signals identified in the survey was stimulated by the protein both in vivo and in vitro. Downstream G-rich tracts, therefore, are a common auxiliary element in mammalian polyadenylation signals. Sequences capable of binding hnRNP H protein with varying affinities may play a role in determining the processing efficiency of a significant number of mammalian polyadenylation signals.

3' Flanking Region↗
PubMed1999

Suitability of air sampling locations downstream of bends and static mixing elements.

The revised standard for sampling effluent air from stacks and ducts of the nuclear industry places limits on the non-uniformity of velocity and contaminant profiles at the sampling location; namely, the coefficients of variation must not exceed 20% over an area that encompasses at least the center 2/3 of the cross sectional area. Tests were conducted to characterize the degree of mixing at downstream locations as affected by several types of flow disturbances, including 90 degree elbows and commercial static mixing devices. Flow straighteners were incorporated into the ducting upstream of the mixer to be tested to simulate the dampening of flow turbulence that might occur because of upstream HEPA filters. The coefficients of variation of velocity and tracer gas concentration measured in a straight tube at a distance of 3 diameters downstream from a 90 degree elbow were 17% and 69%, respectively. The mixing is impacted by the upstream flow turbulence. Without a flow straightener, the tracer gas concentration coefficient of variation was reduced to 33% at the 3-diameter location. The use of static mixing elements can greatly enhance the mixing process. A ring placed just downstream of a 90 degree elbow, which blocks the outer 56% of the cross sectional area, results in a coefficient of variation of 19% for tracer gas concentration at the 3-diameter location. Pressure loss across the elbow with the ring is about nine times that of the basic elbow. One of the commercially available static mixers provides coefficients of variation that are less than 10% for both velocity and tracer gas concentration at 4 diameters downstream from the mixer with a pressure loss that is only about 3.5 times as large as that of a 90 degree elbow.

Air Pollutants, Radioactive↗
PubMed2005

Specific signals at the 3' end of the DHFR gene define one boundary of the downstream origin of replication.

The Chinese hamster dihydrofolate reductase (DHFR) origin of replication consists of a 55-kb zone of potential initiation sites lying between the convergently transcribed DHFR and 2BE2121 genes. Two subregions within this zone (ori-beta/ori-beta' and ori-gamma) are preferred. In the DHFR-deficient variant, DR8, which has deleted a 14-kb sequence straddling the 3' end of the DHFR gene, early-firing origin activity in the downstream ori-beta/ori-beta' and ori-gamma regions is completely suppressed. We show that the critical deleted sequences reside within a 168-bp segment encompassing the intron 5/exon 6 boundary, exon 6, 54 bp of the 3' untranslated region (UTR), but not the three natural polyA sites. In wild-type cells, this sequence efficiently arrests transcription in a region a few kilobases downstream, which coincides with the 5' boundary of the replication initiation zone. In DR8, DHFR-specific transcripts efficiently use an alternative sixth exon (6c) and polyA signals near the middle of the former intergenic region to process primary transcripts. However, transcription proceeds to a position almost 35 kb downstream from these signals, and replication initiation can only be detected beyond this point. When the wild-type 168-bp 3' element is inserted into DR8 at the same position as alternative exon 6c, transcription is arrested efficiently and initiations occur almost immediately downstream. Thus, the normal 3' end of the DHFR gene constitutes a boundary element not only for the gene but also for the local origin of replication.

3' Flanking Region↗
PubMed2006

Targeting downstream effectors of epidermal growth factor receptor/HER2 in breast cancer with either farnesyltransferase inhibitors or mTOR antagonists.

In breast cancer, there is an increasing recognition of the pivotal role played by the epidermal growth factor receptor (EGFR) and HER2 together with the various downstream signal transduction pathways, in particular the Ras/Raf/Mek/erk1/2 pathway that regulates cell proliferation together with the phosphatidylinositol-3-OH kinase (PI3K)/Akt/mTOR pathway that is implicated in cell survival. While monoclonal antibodies and small molecule tyrosine kinase inhibitors targeted against EGFR/HER2 are now being used for breast cancer therapy, there is considerable interest in also targeting the critical downstream pathways that cells may remain dependent upon. Activation of these downstream pathways in breast cancer may be associated with resistance to either conventional endocrine or cytotoxic therapies or, indeed, lack of response to EGFR/HER2-targeted approaches. Farnesyltransferase inhibitors (FTIs) were initially developed to target Ras activation, although their mechanism of action may be more nonspecific. Trials in breast cancer have been completed with FTIs alone or in combination with endocrine or cytotoxic therapy. Activation of the PI3K/Akt pathway has also been associated with resistance to either tamoxifen or estrogen deprivation, and preclinical studies have shown that the mTOR antagonists can restore endocrine sensitivity in breast cancer cells. Randomized phase II/III trials of aromatase inhibitors combined with mTOR antagonists are in progress and have been powered to detect whether combined therapy can significantly prolong time to disease progression compared to endocrine therapy alone. Finally, preclinical experiments are now investigating whether downstream agents should be combined with upstream EGFR/HER2 therapies to produce maximal blockade of vertical signal transduction pathways. Subsequent trials will be needed to see whether combinations of novel STIs are well tolerated and how they may further enhance clinical benefit in breast cancer.

Antineoplastic Agents↗
PubMed2005

The flow field downstream of an oscillating collapsed tube.

A two-component laser Doppler anemometer was used to determine the velocity of aqueous flow in the region from 0.25 to 2.5 diameters downstream of a collapsible tube while the tube was executing vigorous repetitive flow-induced oscillations. The Reynolds number for the time-averaged flow was 10,750. A simultaneous measurement of the pressure at the downstream end of the tube was used to align all the results in time at sixty locations in each of the two principal planes defined by the axes of collapse of the flexible tube upstream. The raw data of seed-particle velocity were used to create a periodic waveform for each measured velocity component at each location by least-squares fitting of a Fourier series. The results are presented as both velocity vectors and interpolated contours, for each of ten salient instants during the cycle of oscillation. In the plane of the collapse major axis, the dominant feature is the jet which emerges from each of the two tube lobes when it collapses, but transient retrograde flow is observed on both the central and lateral edges of this jet. In the orthogonal, minor-axis plane, the dominant feature is the retrograde flow, which during part of the cycle extends over the whole plane. All these features are essentially confined to the first 1.5 diameters of the rigid pipe downstream of the flexible tube. These data map the temporal and spatial extent of the highly three-dimensional reversing flow just downstream of an oscillating collapsed tube.

Animals↗
PubMed1986

Two-component laser velocimeter measurements downstream of heart valve prostheses in pulsatile flow.

Elevated turbulent shear stresses resulting from disturbed blood flow through prosthetic heart valves can cause damage to red blood cells and platelets. The purpose of this study was to measure the turbulent shear stresses occurring downstream of aortic prosthetic valves during in-vitro pulsatile flow. By matching the indices of refraction of the blood analog fluid and model aorta, correlated, simultaneous two-component laser velocimeter measurements of the axial and radial velocity components were made immediately downstream of two aortic prosthetic valves. Velocity data were ensemble averaged over 200 or more cycles for a 15-ms window opened at peak systolic flow. The systolic duration for cardiac flows of 8.4 L/min was 200 ms. Ensemble-averaged total shear stress levels of 2820 dynes/cm2 and 2070 dynes/cm2 were found downstream of a trileaflet valve and a tilting disk valve, respectively. These shear stress levels decreased with axial distance downstream much faster for the tilting disk valve than for the trileaflet valve.

Blood Flow Velocity↗
PubMed2000

Scaling of turbulent wall pressure fluctuations downstream of a rearward facing step.

The turbulent boundary layer that forms downstream of a surface discontinuity is locally inhomogeneous. Here, we consider the boundary layer that occurs downstream of a rearward facing step discontinuity on a flat plate that is exposed to a zero incidence, uniform subsonic flow. The wall pressure "point" spectra are measured by small, flush-mounted pressure transducers located at various locations downstream of the step. A new form of the non-dimensional point wall pressure auto-frequency spectrum is proposed that includes the statistical variations of the reattachment location. This form is shown to collapse quite well all of the spectra measured slightly upstream, within, and downstream of the flow reattachment location.

Models, Theoretical↗
PubMed1989

Genes downstream from pucB and pucA are essential for formation of the B800-850 complex of Rhodobacter capsulatus.

The formation of the light-harvesting complex B800-850 (LH-II) of Rhodobacter capsulatus requires, in addition to the synthesis of the polypeptides alpha and beta (the gene products of pucA and pucB), the synthesis of bacteriochlorophyll and carotenoids and the expression of at least one gene localized downstream from the pucBA operon. This was concluded from the observation that a Tn5 insertion downstream from pucBA inhibited the formation of the LH-II complex and the formation of the pucBA mRNA. The Tn5 insertion point was mapped and found to be over 500 base pairs (bp) downstream from the end of the pucA gene, suggesting the presence of additional puc genes. A region of about 3,000 bp including the pucB and pucA genes and DNA downstream from pucA was sequenced and found to contain three open reading frames (ORFs C, D, and E). The polypeptide deduced from the first ORF (C) contains 403 amino acids with strongly hydrophobic stretches and one large and three small hydrophilic domains carrying many charged residues. The other two ORFs contain 113 (D) and 118 (E) codons. The amino acid sequences of the N terminus and two tryptic peptides of an alkaline-soluble Mr-14,000 subunit of the isolated LH-II complex were identical with the deduced amino acid sequence of ORF E.

Amino Acid Sequence↗
PubMed2000

Effects of combination of different -10 hexamers and downstream sequences on stationary-phase-specific sigma factor sigma(S)-dependent transcription in Pseudomonas putida.

The main sigma factor activating gene expression, necessary in stationary phase and under stress conditions, is sigma(S). In contrast to other minor sigma factors, RNA polymerase holoenzyme containing sigma(S) (Esigma(S)) recognizes a number of promoters which are also recognized by that containing sigma(70) (Esigma(70)). We have previously shown that transposon Tn4652 can activate silent genes in starving Pseudomonas putida cells by creating fusion promoters during transposition. The sequence of the fusion promoters is similar to the sigma(70)-specific promoter consensus. The -10 hexameric sequence and the sequence downstream from the -10 element differ among these promoters. We found that transcription from the fusion promoters is stationary phase specific. Based on in vivo experiments carried out with wild-type and rpoS-deficient mutant P. putida, the effect of sigma(S) on transcription from the fusion promoters was established only in some of these promoters. The importance of the sequence of the -10 hexamer has been pointed out in several published papers, but there is no information about whether the sequences downstream from the -10 element can affect sigma(S)-dependent transcription. Combination of the -10 hexameric sequences and downstream sequences of different fusion promoters revealed that sigma(S)-specific transcription from these promoters is not determined by the -10 hexameric sequence only. The results obtained in this study indicate that the sequence of the -10 element influences sigma(S)-specific transcription in concert with the sequence downstream from the -10 box.

Artificial Gene Fusion↗
PubMed1987

An aberrant avian leukosis virus provirus inserted downstream from the chicken c-myc coding sequence in a bursal lymphoma results from intrachromosomal recombination between two proviruses and deletion of cellular DNA.

A chicken bursal lymphoma, LL6, contains avian leukosis virus DNA integrated 3' of the c-myc coding sequences, unlike all other examined bursal lymphomas, which have integrations 5' to c-myc. To better understand this unusual mutation, we examined a molecular clone containing the LL6 c-myc gene and determined the structure of the proviral insertion by DNA sequencing. Viral DNA begins 575 base pairs downstream of the c-myc coding sequences within the untranslated region, disrupting the use of the normal polyadenylation signal. An internal deletion of the provirus extends from within U3 in the 5' long terminal repeat to within the gp37-coding region of the env gene, disabling virus replication and protein synthesis. Both host-virus boundaries appear normal with respect to the site in viral DNA which is joined to host DNA; both long terminal repeats lack the terminal dinucleotide found in unintegrated DNA. However, in contrast to normal integrations, the six bases of cellular sequence at the 5' junction are not repeated at the 3' junction. The DNA sequences immediately downstream of the LL6 recombinant provirus are not part of the c-myc gene; they originate from the same chromosome as c-myc, but at least 15 kilobases (kb) away. In addition, DNA sequences normally residing 3' of c-myc are deleted in LL6. In summary, these results imply that the LL6 provirus is the result of recombination between two proviruses; that both proviruses were originally downstream of c-myc in the same orientation and separated by at least 15 kb; and that the recombination event was preceded, accompanied, or followed by an internal proviral deletion. No transcript could be detected within a 20-kb region downstream of the LL6 provirus, leaving unresolved the question of whether the additional chromosomal alterations make a specific contribution to LL6 tumorigenesis.

Animals↗
PubMed1996

Downstream regulatory elements increase acute and latent herpes simplex virus type 2 latency-associated transcript expression but do not influence recurrence phenotype or establishment of latency.

The role of putative promoter or activator sequences downstream of the herpes simplex virus type 2 latency-associated transcript (LAT) promoter and upstream of the LAT intron was investigated in vivo by constructing and evaluating mutant viruses with deletions in this region. The deletion of LAT promoter sequences upstream of the primary LAT transcript reduced levels of LAT expression during productive infections, compared with the LAT expression level of wild-type virus, and abolished LAT expression during latency. The deletion of the putative downstream regulatory elements reduced but did not eliminate LAT expression during productive and latent infections. The deletion of both regions almost completely eliminated acute LAT transcription, although additional acute LAT-region transcription directed by sequences upstream of either region was detected by reverse transcriptase PCR. The deletion of the downstream elements did not influence the ability of the virus to reactivate from latently infected guinea pigs relative to the ability of the wild-type virus to reactivate; thus, decreased LAT expression did not affect the frequency of recurrence. The deletion of both regions did not affect the ability of the virus to establish latency. We conclude that downstream regulatory elements are necessary for maximal acute LAT expression but do not constitute an independent promoter during latency and do not play an obvious role in the establishment of our reactivation from latency.

Animals↗
PubMed1997

Regulation of EBNA gene transcription in lymphoblastoid cell lines: characterization of sequences downstream of BCR2 (Cp).

During Epstein-Barr virus (EBV) latent infection of B lymphocytes in vitro, six EBV nuclear antigens (EBNAs) are expressed from one of two promoters, Cp and Wp, whose activities are mutually exclusive. Upon infection, Wp is initially active, followed by a switch to Cp for the duration of latency. In this study, the impact on Cp and Wp activity of sequences downstream of the distal EBNA gene promoter, Cp, was assessed in two lymphoblastoid cell lines. Cp activity was detected in constructs extending from just upstream of oriP to the first W1 exon. In contrast, Wp activity required the presence of the next downstream exon, W2. Viral sequences from -2199 to +2680 bp, relative to the Cp transcription start site, were dispensable for Wp activity. Sequences from +155 to +2680 bp, relative to the Cp transcription start site, were dispensable for Cp activity. Deletion of a 200-bp region from +2680 to +2880 bp downstream of Cp decreased both Cp and Wp activity two- to fivefold. Wp activity was also significantly diminished by deletion of the sequences from +2880 to +3000 bp downstream of the Cp transcription initiation site, which encompassed the Wp CCATT box. Based on deletion analyses of 10.3 kb of viral genomic sequence extending from just upstream of oriP to the first Wp, the only deletions which significantly upregulated Wp activity were those which abrogated Cp activity. However, reporter constructs in which the orientation of Cp was reversed displayed Wp activity comparable to that of reporter constructs in which Cp was deleted, even though the steady-state level of Cp-initiated transcripts from the inverted promoter was indistinguishable from that observed with Cp in normal orientation. This is the first direct evidence to support transcriptional interference as the mechanism for the mutually exclusive behavior of Cp and Wp.

Cell Line↗
PubMed1990

Sequences downstream of the transcription initiation site modulate the activity of the murine dihydrofolate reductase promoter.

The murine dihydrofolate reductase gene is regulated by a bidirectional promoter that lacks a TATA box. To identify the DNA sequences required for dihydrofolate reductase transcription, the activities of various templates were determined by in vitro transcription analysis. Our data indicate that sequences both upstream and downstream of the transcription initiation site modulate the activity of the dihydrofolate reductase promoter. We have focused on two regions downstream of the transcription initiation site that are important in determining the overall efficiency of the promoter. Region 1, which included exon 1 and part of intron 1, could stimulate transcription when placed in either orientation in the normal downstream position and when inserted upstream of the transcription start site. This region could also stimulate transcription in trans when the enhancer was physically separate from the promoter. Deletion of region 2, spanning 46 nucleotides of the 5' untranslated region, reduced transcriptional activity by fivefold. DNase I footprinting reactions identified protein-binding sites in both downstream stimulatory regions. Protein bound to two sites in region 1, both of which contain an inverted CCAAT box. The protein-binding site in the 5' untranslated region has extensive homology to binding sites in promoters that both lack (simian virus 40 late) and contain (adenovirus type 2 major late promoter and c-myc) TATA boxes.

Animals↗