The regulation of elongation by eukaryotic RNA polymerase II: A recent view

The elongation of mRNA by RNA polymerase II (RNAPII) is controlled by the d iverse actions of cis- and trans-acting elements that respond to a variety of biological signals. Elongation regulation, which determines the processi vity of RNAPII, occurs during the steps of transcription initiation and elo ngation through both negative and positive influences. It has been generall y accepted that negative elongation factors repress the elongation reaction . It is also generally accepted that positive elongation factors act by all owing the stalled RNAPII to escape from an inactive state, thus facilitatin g the production of full-length transcripts. However, recent data suggests that these opposing regulatory mechanisms can be achieved through a couplin g pattern, rather than through independent activity. In addition, biochemic al experiments using 5,6-<(d)underbar>ichloro-1-beta -D-(r) under bar ibofu ranosyl (b) under bar enzimidazole (DRB) have identified several factors in volved in DRB-sensitive transcription, and elucidated the me chanism of int erplay between the positive and negative elongation factors. Here, we will review the major findings from studies on RNAPII elongation control. We wil l further discuss the properties of newly identified factors that have resu lted from studies on the action of DRB on elongation.