Transcription bubble

The transcription bubble size is usually 12 to 14 base pairs, which allows the incorporation of complementary RNA nucleotides by the enzyme with ease.

[2] The transcription bubble is formed when RNA polymerase binds to a promoter site and unwinds a small portion of the DNA double helix.

[8] Once it binds to the DNA, RNA polymerase turns from a closed to an open complex, forming the transcription bubble.

[8] The holoenzyme composition dissociates after transcription initiation, where the σ factor disengages the complex and the RNA polymerase, in its core form, slides along the DNA molecule.

[9] The double helix DNA is unwound and a short nucleotide sequence is made accessible on each strand.

[11] In eukaryotes, specific subunits within the RNA polymerase II complex allow it to carry out multiple functions.

After about 25 base pairs of the DNA double strand are unwound, RNA synthesis takes place within the transcription bubble region.

A molecular structure composed of unwound and unpaired DNA, where a short stretch of nucleotides are exposed on each strand of the double helix, allowing RNA polymerase binding, and nascent RNA synthesis within this region.