Stability of transcription complexes on class II genes.

Commitment of a TATA box-driven class II gene to transcription requires binding of only one transcription factor, TFIID. Additional factors (TFIIB, TFIIE, and RNA polymerase II) do not remain associated with the TFIID-promoter complex during the course of transcription. This indicates that there are two intermediates along the transcription reaction pathway which may be potential targets for the regulation of gene expression.