Figure 14.16 illustrates initiation of transcription. Besides the initiation complex of DNA, two other regions will bind with proteins that help activate RNA polymerase. Enhancer regions are much farther away and activator proteins bind with them. The activator proteins stimulate the transcription complex although it is not clear how they do this since they are so far away. Silencer regions have inhibitory effects that counteract the effects of enhancers.
Repressor proteins bind with the silencer regions to bring about inhibition.
Gene Inactivation Genes may be inactivated by the structure of chromatin. Heterochromatin is clumped chromatin that can block transcription by making the DNA physically unavailable for transcription. The binding of proteins can regulate longevity of the mRNA in the cytoplasm. The function and stability of the completed protein can be regulated by chemical modifications.