Ef1a promoter transcription start site.
Dec 3, 2021 · The two promoters tested in this work (i.
Ef1a promoter transcription start site These transcriptional elements may drive aberrant splicing and/or polyadenylation between transgene-contained and genomic sequences. Results In the present study we begin to This experiment confirms that constructs containing the EF1a promoter can undergo epigenetic silencing in embryonic development. ter, denotes the site for termination of transcription. They are also unlike promoters in that the introns must be downstream of the transcription start site to affect expression. The 1172bp version actually contains an intronic sequence, which is occasionally spliced out. The CMV-initiator (Inr) is underlined. Dec 6, 2014 · It is a cellular-derived enhancer/promoter with decreased cross-activation of nearby promoters, therefore hypothetically decreasing the risk of genotoxicity. Here, we present an analysis of the transcription start sites (TSSs) in the migratory locust, Locusta migratoria, which has a genome size of 6. In practice, the term "promoter" describes the combination of the promoter (RNA polymerase binding site) and operators (response elements). Aug 21, 2011 · For the CCR5 locus, although the EF1A promoter with or without the intron had no effect on the expression of any gene studied, the PGK promoter upregulated both CCR5 (ninefold) and CCR3 (twofold Many genes employ multiple promoters that allow for differential RNA isoform expression, a fundamental component of tissue diversity and response to environmental changes 1, 3, 4, 5. Optimal promoter selection can enhance target specificity and gene expression. (enAsCas12a, herein referred to simply as Cas12a) for some-by-some combinatorial knockout screens and genome-wide single-gene screens. Transcription start sites (TSS) are integral to the initiation of gene transcription, marking where RNA polymerase begins synthesizing RNA. The SV40 early promoter exhibits all the hallmarks of eukaryotic promoters, containing elements that function when positioned near the start site of transcription and other positionally flexible elements that constitute a transcriptional enhancer. b, Workflow for AAV-based retinal cell-type targeting screen. SoEF1A1: Saccharum These paRNAs have also been named promoter-proximal transcription start site RNAs , promoter upstream transcripts , or transcription start site-associated RNAs . 19, 20 This approach compares favorably to Cas9-based screens largely because several guides can be easily multiplexed in a single vector, resulting in a more Initiation sites of transcription, also known as Transcription Start Sites (TSSs), represent the definitive points at which the process of RNA synthesis commences, employing the DNA strand as a template. Therefore, efforts have been directed to create a super core promoter, by combining different core promoter elements, such that this composite promoter has a higher efficacy than the existing viral and eukaryotic Jul 8, 2019 · a, Synthetic promoter design strategies. U6 promoter Jan 3, 2014 · Sequence analyses showed that all of the promoters contain three conserved putative cis-acting elements which are located upstream of the transcription start site. The distributions of seven TFREs (SP1, NF-κB, STAT, HSF, GATA, TEF and CEBP) were assessed for the EF-1α, CAG and CMV promoters. The characterization of core promoters is crucial for exploring the regulatory code of transcription initiation. This sequence is fused to a DNA element providing basal promoter activity in mammalian cells derived either from the CMV IE or HSV thymidine kinase promoters. Minimal promoters. Furthermore, elongation factor 1a promoter (EF1a) -driven GFP reporter and Myostatin promoter (MyoP)-driven Follistatin (Fst) were successfully targeted into the pRosa26 locusby traditional homologous recombination (HR) strategy. Oct 28, 2024 · Basics of Transcription Start Sites. Most metazoan polymerase II-transcribed genes Jan 30, 2023 · sites and polyadenylation sites within the vector sequences. Jan 3, 2014 · A putative TATA box (consensus CTATAWATA) sequence was located at a region approximately between –10 and –45 relative to the transcription start site (TSS). Specifically, transcripts containing the FIV rev-responsive element (RRE) upstream of the EF1A promoter were not detected, nor Sep 13, 2023 · Previously, we reported the optimization of an enhanced version of Cas12a from Acidaminococcus sp. 5' (Hin dIII) and 3' (Sal I) restriction sites are shown in lower case, bold. Both promoters consist of a basal region directing basal transcription and a distal sequence element (DSE) that enhances transcription (2) (Fig. Hi John. Sequence analyses showed that EF1A promoters have putative cis-acting elements which are predicted based on the sequence similarity and the relative position to the transcription start site (TSS Truncated RNA polymerase III promoter for human U6 snRNA used in pSIREN vectors such as pSIREN-RetroQ-ZsGreen1. c, Confocal images of sections of AAV-infected retinas. 25, 27 Even so, the CMV promoter has shown significantly increased transfection levels compared to the EF1a promoter, especially in hMSCs. Cleavage at this site generates the products mRNAp (5′) and mRNAp (3′). 3 kb of D. Beware some genes have alternative promoters. The start site maps to an adenine located within a consensus initiator element. (A) The Lefty1/Lefty2 locus in the mouse (top) and human (bottom) genomes. Taking advantage of recent advances in genome-wide sequencing approaches, Vo ngoc an … Alternatively, constitutive human EF1a or mouse pPGK promoters are used . X03922. A widely used promoter/enhance element present in gene vectors to ensure high transgene expression Mar 30, 2021 · Results. The CEBP, NFκB, STAT, GATA and HSF TFREs were abundant in the EF-1α promoter (Table 1). The comprehension of TSSs is vitally important in elucidating patterns of gene expression, the mechanics behind their regulation, and the Jan 1, 2021 · The profound difference in Pol II activity of the H1 and 7SK promoters is quite remarkable as they share a similar type 3 RNA Pol III promoter architecture (7). Jul 27, 2020 · RNA polymerase III (Pol III) promoters, such as 7SK, U6, and H1, are widely used for the expression of small noncoding RNAs, including short hairpin RNAs for RNAi experiments and guide RNAs for CRISPR-mediated genome editing. These sites are typically located near promoter regions, which are sequences of DNA that facilitate the binding of transcription machinery. The promoter is active in most mammalian cell types. In addition, all of the promoters also have the 5'UTR intron but with a different lengths. Recently, we evaluated three different human elongation factor 1 alpha (EF1α) promoters. My transfection efficiency in See full list on addgene. , 93 ( 2002 ) , pp. The backbone integrated with 2xSp1 (two yellow circles) is outlined in construct 2. 1b) or removing it to test for potential May 30, 2017 · Promoter activity is related to transcription factor-binding sites and TFREs. Be the first to answer. Jun 26, 2018 · transcription start site (TSS; see the figure, part a), and ‘dispersed’ or ‘broad’ promoters 45, which have multiple closely spaced TSSs that are used with similar frequency (see the Mar 1, 2002 · More specifically, the luciferase gene was linked to the IE1 or IE2 promoters keeping the other transcription start site on the construct (C and D in Fig. org Jul 24, 2007 · The observation that there is transcriptional activity across the EF1a promoter suggested that a species of RNA is generated specifically to promoter regions. No, translation start site is A start site is a biochemically signaled nucleotide or set of nucleotides for attachment either to the Epigenomes or the DNA. I am using 2nd-generation lentiviral system (psPAX2 and VSV-G). 1 A). (B) Transcription of the gene leads to the formation of a steady-state between mRNA synthesis and degradation. Jun 29, 2021 · Next, RNAP selects a transcription start site (TSS) by placing the start-site nucleotide and the next nucleotide of the “template DNA strand” into the RNAP active-center product site (P site) and addition site (A site), respectively, and binding an initiating entity in the RNAP active-center P site (Fig. sequences with a regulatory element from another highly-expressed soybean eEF1A gene (GmScreamM1) [34]. The TSS is embedded within a core Jul 7, 2007 · The observation that there is transcriptional activity across the EF1a promoter suggested that a species of RNA is generated specifically to promoter regions. Available methods for TSS detection in bacteria use ve … Aug 28, 2015 · Here we demonstrate that at least three HSEs, with different configurations, exist in the UBC promoter: two distal, residing within nucleotides -841/-817 and -715/-691, and one proximal to the transcription start site (nt -100/-65). Accurately detecting transcription start sites (TSS) is a starting point for understanding gene transcription, and an important ingredient in a number of applications necessary for functional gene annotation, such as gene and operon predictions. magna elongation factor 1 α-1 (EF1α-1) promoter/enhancer, including the Aug 12, 2022 · In this work, we set out to create mice susceptible to the SARS-CoV-2 coronavirus. Using promoter truncation experiments and site-directed mutagenesis within potential transcription factor binding sites, we suggest that the minimal promoter contains more than one binding site for the recently identified parasite-specific ApiAP2 transcription We have isolated the Xenopus EF-1αS gene and used microinjection techniques to identify promoter elements responsible for embryonic transcription. To characterize the 5′ end and transcription start site (TSS) of this EF1a promoter-associated RNA, 5′ RACE was performed. Mar 14, 2012 · The world of RNAs is much more complex than previously thought, and has rapidly emerged as one of the most actively researched topics in the life sciences. Using pronuclear microinjection of the transgene construct, we obtained six founders with the insertion of the EF1a-hACE2 transgene, from which four independent mouse lines were established. EF1a showed high activity and hypomethylation at the locus. Oct 14, 2015 · Here is the BRCA2 promoter sequence aligned to BRAC2 gene. Aug 15, 2000 · Primer extension analysis identified the predominant transcription start site 166 bp upstream of the AUG codon. In the core promoter conserved motifs are shown with consensus sequences and the position from the transcription start site The core (basal, or minimal) promoter is a specialized DNA sequence which directs transcription initiation and is located -50 to +50 bp from the transcription start site (TSS) . Dec 3, 2021 · The two promoters tested in this work (i. Recently, two findings in this field were reported and given special attention: promoter-associated RNAs (paRNAs), a novel class of RNAs with numerous potential functions; and promoter-targeted RNA-induced transcriptional gene regulation, a Dec 1, 1999 · The second plasmid enables cloning of a cDNA of interest downstream of a synthetic heptamerized Tc operator transcription regulatory DNA sequence. The EF-1 alpha S promoter is extremely active in the early Xenopus embryo where EF-1 alpha S transcripts account for as much as … Conserved high enhancer feature (CHEF) regions contain a conserved regulatory code. Authors took a stringent approach to characterize the expression of the Jan 3, 2014 · A putative TATA box (consensus CTATAWATA) sequence was located at a region approximately between –10 and –45 relative to the transcription start site (TSS). magna elongation factor 1 α-1 (EF1α-1) promoter/enhancer, including the A1 insulated vectors also had significantly less proviral integrations near the transcription start sites (TSS) of genes. These elements are included a TEF1, a TELO and TATA boxes. Left Sep 19, 2005 · RESULTS AND DISCUSSION. The TATA box motifs are shown as open boxes, and the positions of SV40 early (SVE EES1 and EES2) and CMV transcription starts sites are indicated by arrows. Most of these promoters appear tissue-selective, exhibiting higher activity in one Jan 10, 2020 · Variations in transcription start site (TSS) selection reflect diversity of preinitiation complexes and can impact on post-transcriptional RNA fates. Jan 1, 2017 · Transcription by RNA polymerase II (Pol II) is dictated in part by core promoter elements, which are DNA sequences flanking the transcription start site (TSS) that help direct the proper initiation of transcription. 5 Gb. The observation that there is transcriptional activity across the EF1a promoter suggested that a species of RNA is generated specifically to promoter regions. There are several types of core promoters. This element is responsible for initiating the transcription of your insert into RNA. e. In the above example (BRCA2), a CpG island is displayed in the proximal promoter. 11, 12, 13 During early transcription, the ITC tends to Mar 10, 2011 · Here, we demonstrate that a back-to-back configuration of the mouse Pgk1 and human eukaryotic translation elongation factor 1 alpha 1 promoters provided a substantive increase in both transgene The full-length H1 promoter was truncated from the 5'-end by 50-bp steps up to position 74 (all numbers relate to the distance from the transcription start site). The core promoter consists of the TSS and proximal non-coding sequences, which are critical in transcriptional regulation. To ensure that transcription from the integrated transgenic EF1A promoter initiat-ed in a similar position to endogenous EF1A, we performed RT-PCR (fig. The CAG promoter did not contain CEBP and GATA the different promoters, particularly in the transcriptional start site. These in vivo expression studies have identified an enhancer fragment, located approximately 4. Aug 23, 2024 · a Sp1 and NF-kB binding sites were introduced upstream from EFS-NC promoter (pEFS-NC) (construct 1). The pPGK promoter ensures a low level of expression, the duration of which is unknown . However, several putative cis-regulatory elements were discovered. Apr 3, 2014 · Here, we'll cover the promoter, which is necessary for getting the plasmid express our gene of interest. Apr 12, 2021 · The PCR amplicon spans ~ 150 bp upstream of the transcription start site, exon 1, intron 1, and part of exon 2 to the endogenous start codon. Promoter engineering attempts to modulate promoter transcriptional capacity by altering promoter DNA sequence. The promoter is a type III Pol III promoter in that all elements required to control expression of the shRNA are located upstream of the transcription start site (Paule and White, 2000). However, sometimes the transcription from promoter EF1a becomes an order of magnitude lower a few days after transfection . 28 Mammalian promoters have also been explored for plasmid-based transgene expression, including the elongation factor 1a (EF1a) promoter, the apoA1 promoter, the apoE promoter, the albumin promoter, the alpha-1 antitrypsin promoter, and others (for review, see ). Therefore, the accurate id … EF1A-GFP expression by silencing transcrip-tion. 28 FV vectors have a strong CTCF insulator in the LTR 29, but the A1 insulator improved safety when stressed with a genotoxic SFFV promoter. The three promoters were put into the same expression vector, pAC-luc, driving expression of the luciferase cDNA. Promoter engineering often requires to obtain high and sustained expression or provides a wider range of gene expression. Recently, we evaluated three different human elongation factor 1 alpha (EF1α) To allow ubiquitous expression in D. 2019). 2004a). Nucleotides number relative to their start codon (ATG) show on top of the graph. , CMV and EF1a) are widely used promoters for gene delivery shown to produce high levels of transfection in numerous cell types. Usage of the expected +1 transcriptional start site was most accurate from the U6 promoter, while the accuracy in using this site from the 7SK and H1 promoters was variable based on the specific molecule being transcribed. Jun 26, 2018 · Transcription typically initiates at a defined position, the transcription start site (TSS), at the 5ʹ end of a gene, which we refer to as the gene start. Binding sites for cell-type-specific transcription factors involved in cell fate determination such as Runx2, MyoD, or myogenin are frequently observed. S2) (19, 21). 4xSp1 (four Apr 10, 2024 · During promoter escape, the transcription complex undergoes structural and compositional changes. a key consideration in selecting promoters for 976 to 798 bp upstream of the transcription start site (TSS). Sequencing of a 2-kb 5'-flanking promoter region revealed no TATA element. We previously characterized the static structures of transcription start site usage within promoters at the base pair level, based on large-scale sequencing of transcript 5' ends. ATG is the translation start site. TATA-Box and TFIIB site are shaded in grey. Feb 1, 2018 · These promoters may be useful for promoter engineering, which is now important to the synthetic biology. Jun 23, 2017 · The core EF1a promoter is only about 200-300bp in size. 28 Based on in silico analysis of the Des gene, a 144-bp sequence from 970 to 826 bp relative to the TSS (Figure 1A) was chosen as the first module of the hybrid promoter and called enhancer 1 (enh1). It was predicted to bind TFs such as MyoD, Myf6, Sp1 and SRF. However, the current understanding of insect core promoters is focused on those of Diptera (especially Feb 1, 1993 · The simian DNA tumor virus SV40 regulates synthesis of early and late viral transcripts from two divergent and overlapping promoters. In UCSC genome broswer, you can turn on CpG island feature, if there is CpG island in the promoter sequence, the sequence is highly likely a true promoter. 2, the MCMV promoter showed higher promoter strength than the HCMV and the EF-1α promoter in many cell lines, although in three cell lines (HeLa, COS, and CHO) the EF-1α promoter showed the highest promoter activity. To ensure the ubiquitous expression of the human ACE2 gene we used the human EF1a promoter. In comparison with the CMV promoter, the eukaryotic translation elongation factor 1 α (EF‐1α, gene symbol EEF1A1) promoter increased the transfection efficiency, the transgene expression, the proportion of expression‐positive clones and the copy number of the episomal vector in long‐term culture. May 30, 2020 · The human elongation factor 1 alpha (EF-1 alpha) first intron highly enhances expression of foreign genes from the murine cytomegalovirus promoter J. ↓, Potential processing site. 1A). Side-by-side comparison of the two GFP constructs with CAG and EF1a promoters was performed in the transgenic monkey project (Seita et al. Upstream (upper panel) and downstream promoter sequences (lower panel) relative to the transcription start site (+1) are aligned separately. Dark boxes represent the 72- and 21-bp repeats of SV40. These systems frequently employ the cytomegalovirus (CMV) promoter to drive recombinant gene transcription. 转录起始位点（transcription start site，TSS ）是指一个基因的5'端转录的第一个碱基，它是与新生RNA链第一个核苷酸相对应DNA链上的碱基，通常为一个嘌呤（A或G）。 To generate the GmSM8Core-pFLEV construct (100 bp GmScreamM8 core promoter sequence replacing the 46 bp 35S core promoter sequence), a 100 bp region [-60 bp to +40 bp, relative to the transcription start site (TSS)] of GmScreamM8 was initially amplified with GmSM8Core_F/R primers and then subcloned into pFLEV with appropriate restriction sites. The CHO EF-1α promoter shows higher transcription efficiency in comparison with human EF-1α promoter (Romanova and Noll, 2018). Expression of recombinant genes in HEK293 cells is frequently utilized for production of recombinant proteins and viral vectors. The genomic differences, including lower precision of transcription initiation and fewer constraints on the distance from transcription factor binding sites or regulatory elements to TSSs, were revealed in locusts compared with Drosophila However, sometimes transcription can start at a different position (see for instance the article "RNA Polymerase II Activity of Type 3 Pol III Promoters", where the H1 promoter starts +6 to +68 relative to the start site of transcription produced the same steady-state concentration of EIB messenger RNA as a virus with a wild-type E1B promoter region when EIA protein Oct 31, 2019 · Alternatively, a variety of strong promoters, including human elongation factor-1 alpha (EF-1α) promoter and CAG promoter (a combination of the CMV immediate early enhancer and the chicken β-actin promoter), have been exploited to achieve the high-level expression of various genes [Citation 19, Citation 20]. 0-fold in NIH3T3 (mouse fibroblast cell lines Jul 16, 1990 · To identify the promoter region of the EF-1α gene necessary for efficient gene expression, we constructed four pEF-CAT plasmids that have the bacterial cat gene fused to four different sites of the human EF-1α gene: (i) ligated to the end of the TATA box (pEF220-CAT); (ii) ligated in exon 1 (pEF204-CAT and pEF233-CAT), and (iii) ligated in The Lenti-X Tet-On 3G Inducible Expression System (EF1alpha Version) is a tetracycline-inducible lentiviral gene expression system that allows you to produce high titers of recombinant, VSV-G pseudotyped lentiviruses for the purpose of establishing a tightly inducible expression system in both dividing and non-dividing cell types. I am expressing two genes (CAR and a reporter) under EF-1a promoter in a lentiviral vector. The full-length CMV promoter is the most commonly used and versatile regulatory element with a TATA-box-containing promoter region and an enhancer region from −550 bp to −39 bp relative to the transcription start site (tss) (GenBank Accession No. Promoter regions are located within ~2 kb upstream of the transcriptional start site, whereas enhancers may be located at some distance from promoter sequences and exert long-range effects. 14 Consistent with other published . 183 - 187 Google Scholar Aug 24, 2020 · Alternatively, constitutive human EF1a or mouse pPGK promoters are used . The transcription starting point, TSP1, for mRNA1 relates to promoter P1. The rest Dec 28, 2020 · EF1-alpha is considered a ubiquitous/constitutive promoter; it is effective in all animal cells and tends to provide strong expression. The vectors included T2A vector with T2A-separated Ii and GFP under the same MSCV promoter, dual-promoter vectors with separate promoters for Ii and GFP (called MSCV or EF1a according to the promoter driving Ii expression), and a vector with EF1a driving a fusion of Ii/GFP (called Fusion vector). To build constructs with low-expression promoters, an NsiI restriction cloning site was inserted by site-directed mutagenesis before the EF1α promoter in pEF5B/FRT (Nager et al. Dec 12, 2006 · Background Mammalian promoters do not initiate transcription at single, well defined base pairs, but rather at multiple, alternative start sites spread across a region. In this study, a series of deletion and scanning mutations was introduced in the promoter region of human EF-1 alpha … The precise and accurate identification and quantification of transcriptional start sites (TSSs) is key to understanding the control of transcription. Transcription factor–bound regions from ChIP-seq (red bars), mouse and human syntenic regions (gray bars), and H3K27ac ChIP-seq data are displayed on the mm10 and hg19 assemblies of the University of California at Santa Cruz (UCSC Where is the exact transcription start site of the EF1a promoter? Question. Biotechnol. 7, 8 As initial transcription proceeds, the upstream end of the initially melted DNA bubble remains in place, whereas the downstream junction of the bubble is further unwound, enlarging the DNA bubble 9, 10 in a process termed DNA scrunching. RESULTS Feb 6, 2019 · These introns are therefore unlike enhancer elements, which operate over long distances in both directions to activate transcription from a promoter (Zabidi and Stark, 2016). Another motif that we found is TELO box (consensus AACCCTA). However, the current understanding of insect core promoters is focused on those of Diptera (especially transcription start site was mapped by rapid amplification of cDNA ends (59-RACE). Mar 30, 2021 · Background Core promoters have a substantial influence on various steps of transcription, including initiation, elongation, termination, polyadenylation, and finally, translation. However, the mechanistic basis of CMV-mediated transcriptional … Nov 23, 2023 · Here, using CAGE-seq, the authors show that transcription start site choice in thousands of genes may endow transcripts with distinct post-transcriptional fates, with dynamic switching defining Nov 25, 1994 · Most eukaryotic cells abundantly express polypeptide chain elongation factor-1 alpha (EF-1 alpha), an enzyme which catalyzes the GTP-dependent binding of aminoacyl-tRNA to ribosomes. 1) 20. Expected transcription start site is 8bp downstream of this feature. 4 kb upstream of the transcription start site, that is required for maximum expression from the EF-1αS Feb 1, 1993 · The simian DNA tumor virus SV40 regulates synthesis of early and late viral transcripts from two divergent and overlapping promoters. Transcription of the Xenopus laevis EF-1 alpha S gene commences at the mid-blastula stage of embryonic development and then continues constitutively in all somatic tissues. magna, the original chicken β-actin promoter was replaced with a 2. Embryonic (and other) stem cells are more difficult to target than other cells because they don't express genes under the cell-type specific promoters that are often used for other populations of cells, which is why you're seeing it used specifically for that Feb 14, 2002 · As shown in Fig. Asked 29th Aug, 2022; Meng Sun; Hello, I didn't find the TATA box sequence in this EF1a sequence Mar 30, 2021 · Background Core promoters have a substantial influence on various steps of transcription, including initiation, elongation, termination, polyadenylation, and finally, translation. Synthetic promoters/introns consisting of an element tetramer, a core promoter, and variant intronic sequences were transcriptionally fused to a green fluorescent protein (gfp) reporter gene and evaluated using both transient expression in Mar 3, 2017 · (a) The 5′-LTR contains a TATA box (nt −30/−21) upstream of the transcription initiation site at the U3-R junction (mRNA start site at + 1 is indicated by an arrow). Mar 9, 2020 · A Kozak sequence is found at the translation start site (the methionine ATG) in the mRNA, which can be hundreds of nucleotides away from the promoter or the 5' transcription start site. All of plants EF1A promoters have single putative TATA box except for MeEF1A1 that contain two putative TATA boxes. To allow ubiquitous expression in D. Jan 3, 2014 · The elongation factor 1 alpha promoter architecture in plants. They transcribe approximately from the start of or within the promoter, and include long, short and tiny RNA molecules. We previously reported dual RNA polymerase activity (Pol II/III) for the human H1 promoter and demonstrated that this promiscuous RNA polymerase use can be exploited for The promoter is a major element in the expression cassette of gene therapy vectors. The MCMV promoter was more active than the HCMV promoter by 13. We have produced vector constructs carrying the internal enhancer/promoters MNDU3, MSCV, or EFS driving clinically relevant transgenes for modification of primary human T lymphocytes and Mar 3, 2017 · (a) The 5′-LTR contains a TATA box (nt −30/−21) upstream of the transcription initiation site at the U3-R junction (mRNA start site at + 1 is indicated by an arrow). , 2017). Download scientific diagram | The elongation factor 1 alpha promoter architecture in plants. A number of strategies exist for identifying potential transcription start sites (TSS) and enhancer elements on a genome-wide scale. Recently, we evaluated three different human elongation factor 1 alpha (EF1α) The promoter is a major element in the expression cassette of gene therapy vectors. Unfortunately, only one line Mar 7, 2014 · Optimal promoter selection can enhance target specificity and gene expression. The positions are numbered relative to the transcription start site (+1) for CMV or according to the SV40 system . siRNA EF52 is homologous to sequence −104 to −125 relative to the transcriptional start site in the EF1A promoter and was shown previously to mediate TGS of the endogenous EF1A gene (Morris et al. uummlqucicnlgrmfgosrkpiedutinxuldcdegamjjsgciqmjxtnnjxkixbguahdkylnkgbmssyrbcfnxzvu