Consequences of mutations in the upstream promoter region

    The effect of a point mutation at each position upstream from the coding region can be measured by comparing the level of mRNA transcription relative to the un-mutated gene [vertical scale]. The graph shows that transcription is strongly reduced by mutations in the promoter regions at -10 (ATATAA) & -35 (GGCCAATC), and at an upstream enhancer region. Note that mutations at either of two sites immediately 5' to the -35 promoter sharply increase transcription. A mutation at the start point of transcription (bent , fifth base  from the 3' end) turns off transcription entirely. 

    The large majority of mutations in this region have no measurable effect on transcription (relative transcription level ~ 1). Dots on the baseline are positions where the consequences of mutations are unknown.