Transcriptional
Promoters
A
promoter is a short
DNA sequence that signals the RNAPol
where to begin transcription. Comparison of many E. coli
DNA gene sequences shows two common promoter motifs [yellow
boxes] with similar
sequences, which are
located approximately -10 [the TATA Box] & -35
[the CAT Box] bases 5' ('upstream') from the start point of RNA
transcription [blue box]. Similar promoter regions occur in other prokaryotic
and eukaryotic genes.
It is important to remember that
the promoter is a DNA
signal for the downstream start point of transcription at
position +1. The start point of translation is recognizable in the
DNA still further
downstream, but is actually on the transcribed RNA molecule,
at the AUG start codon of the gene. The start
codon does not appear
in the diagram.
Figure © 2004 by Griffiths et al.
; text © 2024 by Steven M.
Carr