Figure 6.21. Action of enhancers.

Figure 6.21Action of enhancers

Without an enhancer, the gene is transcribed at a low basal level (A). Addition of an enhancer, E—for example, the SV40 72-base-pair repeats—stimulates transcription. The enhancer is active not only when placed just upstream of the promoter (B), but also when inserted up to several kilobases either upstream or downstream from the transcription start site (C and D). In addition, enhancers are active in either the forward or backward orientation (E).

From: Regulation of Transcription in Eukaryotes

Cover of The Cell
The Cell: A Molecular Approach. 2nd edition.
Cooper GM.
Sunderland (MA): Sinauer Associates; 2000.
Copyright © 2000, Geoffrey M Cooper.

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