Organization of a eukaryotic protein-coding gene region
convention, the upstream downstream orientation
corresponds to the 5' 3' direction of the DNA
sense strand; it is ordinarily drawn left to
right for convenience.
The transcriptional unit comprises
the expressed exons and intervening
as well as 5' non-coding sequences
required for RNA polymerase binding (Shine-Delgarno sequence)
and trailing 3' non-coding sequences. Outside the
transcriptional area, the 5'
flanking region ("upstream")
region includes the 'CAT box' and 'TATA box' promoters required
for RNA polymerase
recognition prior to transcription.
Enhancers that regulate occurrence, timing,
and amount of transcription occur in both the upstream region
and the 3' flanking region
multiple enhancers may occur many hundreds of nucleotides
Figure © 1997
Klug & Cummings; text © 2016 by Steven M. Carr