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 startpoint
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 startpoint of transcription at position +1. The startpoint 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. [Note that the start codon does not appear in the diagram].
It is important to remember that the promoter is a DNA signal for the downstream startpoint of transcription at position +1. The startpoint 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. [Note that the start codon does not appear in the diagram].
Figure © 2004 by Griffiths et al. ; text © 2011 by Steven M. Carr