Mechanisms of positive control of transcription

(a) Effect of allosteric effector compound Activator protein Effector W No ‘9’, RNA polymerase :transcription , ' ' Promoter Gene Absence of effector prevents i Effector binding to the activator protein binding and éactivator protein facilitates transcription. l transcription by positive ‘ . l regulation. (b) Effect of allosteric inhibitor compound Activator protein RNA polymerase lnhibitog No - - . . :transcription Transcription Promoter Gene Binding of inhibitor to activator Absence of an inhibitor allows protein prevents activator bind- binding of activator protein ing and transcription. and transcription by positive ; regulation.