Promoter-proximal pausing and its release: molecular mechanisms and physiological functions.

For a long time, not much attention had been paid to post-initiation steps in transcription, because it was widely believed that transcriptional control was brought about almost entirely through the regulation of transcription initiation. However, it has become clear that the process of elongation is also tightly controlled by a collection of regulatory factors called transcription elongation factors and contributes, for example, to rapid induction of immediate-early genes and to the control over the viral life cycle. Transcription elongation has attracted attention also because this process is coupled with various RNA processing events. In this review, we discuss biochemical and physiological aspects of elongation control, particularly focusing on the role of the negative elongation factor NELF.