What causes RNA polymerase to pause just after transcription is initiated?

Question

Quizplus · Accepted Answer

Binding of negative elongation factor (NELF) and DRB sensitivity-inducing factor (DSIF) to RNA polymerase causes it to pause just after transcription initiation. This pause allows for proper regulation of gene expression, as well as coordination with other cellular processes. NELF and DSIF are eventually released by positive transcription elongation factor b (P-TEFb), which allows RNA polymerase to resume transcription. While phosphorylation of the C-terminal domain (CTD) of RNA polymerase is involved in transcription elongation, it doesn't cause the initial pause. Production of P-TEFb is also involved in releasing the pause, but it is not the initial cause.

What Causes RNA Polymerase to Pause Just After Transcription Is