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. 2013 Jun 12;8(6):e65932. doi: 10.1371/journal.pone.0065932

Figure 7. UbC intron does not act as a typical transcriptional enhancer.

Figure 7

(A) Schematic representation of the tested DNA constructs. UbC promoter elements contained in the reference construct P3 are the proximal promoter (PP, black solid line, nt −371/−1), the first noncoding exon 1 (Ex1, hatched box, nt +1/+64), and the 5′-UTR intron (Int, open line, nt +65/+876). –Int, construct devoid of the intron sequence. Int(s)-PP-Ex1 and Int(as)-PP-Ex1, constructs where the UbC intron sequence was moved upstream of the proximal promoter, either in the sense or antisense orientation. [Ex1-Int](s)-PP and [Ex1-Int](as)-PP, constructs where the exon 1-intron cassette was moved upstream of PP, in both sense and antisense orientation. (B) Constructs displayed in A were transiently transfected in HeLa cells and luciferase activities were measured 48 h afterwards, normalized on total protein content, and referred to the P3 construct, set equal to 100%. The graph data are the means (±SE) of five independent experiments. Statistical analysis revealed a highly significant difference (***, p<0.001) between P3 and all other constructs investigated.