Question

How is the rate of initiation of RNA polymerase at a given promoter in a transcriptional unit of prokaryotes regulated?

Answer 1

1. In a transcription unit, the activity of RNA polymerase at a given promoter is regulated by accessory proteins that have an ability to recognise start sites.
2. These regulatory proteins can act both positively (activators) and negatively (repressors) with the operator, which is adjacent to the promoter in an operon unit.