Recall that in eukaryotes

Recall that in eukaryotes - regions of actively transcribed...

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Recall that in eukaryotes, DNA is bound to histones in nucleosomal structure. Actively transcribed genes are in the most relaxed form of chromatin (the 10nm chromatin fiber conformation). Nevertheless, a variety of experiments have shown that nucleosomes bound to the promoter or enhancer inhibit the initiation of transcription by blocking the binding of transcription factors and RNA polymerase. Nucleosomal structure is believed to be relieved by proteins known as nucleosome remodeling factors in these regions during transcription. Enhancer and promoter
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Unformatted text preview: regions of actively transcribed genes contain disrupted nucleosomes or fewer nucleosomes and are, therefore, more susceptible to the action of endonucleases. Interestingly, the body of transcribed genes remains in nucleosomal structure. Apparently nucleosomes are not an impassable barrier to RNA polymerase. HMG (high mobility group) proteins may disrupt the interaction between the histone proteins (perhaps especially Histone 1) and the nucleosome during transcription....
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