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Updated: May 9, 2026

Artificial RNA Polymerase II Elongation Complexes for Dissecting Co-transcriptional RNA Processing Events
Published on: May 13, 2019
RNA polymerase II transcription initiation with and without XPB translocase activity
Mario Zurita1, Samantha Cruz-Ruiz2, Eduardo Calvario2
1Departamento de Genética del Desarrollo y Fisiología Molecular. Instituto de Biotecnología,Universidad Nacional Autónoma de México. Av. Universidad 2001, Chamilpa, Cuernavaca, México. mario.zurita@ibt.unam.mx.
None:
A key step in gene expression is the opening of DNA at the transcription start site (TSS), allowing RNA polymerase to begin RNA synthesis. In eukaryotes, RNA polymerase II initiates transcription within the pre-initiation complex (PIC), which includes TFIIH. The XPB subunit of TFIIH drives DNA unwinding at the TSS through ATP-dependent activity. However, some promoters enable transcription without XPB, likely due to intrinsically unstable DNA that does not require active unwinding. This mechanism may reflect an evolutionary remnant of archaeal transcription.
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