THE RNA-POLYMERASE-II ELONGATION COMPLEX

The initiation stage of transcription by RNA polymerase II has long be en regarded as the primary site for regulation of eukaryotic gene expr ession, Nevertheless, a growing body of evidence reveals that the RNA polymerase II elongation complex is also a major target for regulation . Biochemical studies are implicating an increasing number of transcri ption factors in the regulation of elongation, and these transcription factors are being found to function by a diverse collection of mechan isms. Moreover, unexpected features of the structure and catalytic mec hanism of RNA polymerase II are forcing a reconsideration of long-held views on the mechanics of some of the most basic: aspects of polymera se function, In this review, we will describe recent insights into the structures and functions of RNA polymerase II and the transcription f actors that control its activity during the elongation stage of eukary otic messenger RNA synthesis.