of the Promoter site
The RNAPol molecule recognizes the beginning of a transcriptional unit (typically for an mRNA) as a short motif called the Promoter.The Promoter itself is approximately 10 bp 'upstream' [to the 'left' of, or 5' to ] the physical start site of transcription on the Template strand. Note that this "start site" in the DNA is not the same as the "start codon" in the mRNA.
Figure © 2000 by Griffiths et al. ; text © 2010 by Steven M. Carr