Multiple functions of general transcription factors TFIIE and TFIIH in transcription: possible points of regulation by trans-acting factors.
General transcription factors together with RNA polymerase II assemble on the promoter DNA and initiate transcription accurately in response to a variety of signals. Such signals enhance preinitiation complex formation by targeting components thereof via several alternative pathways. Two components of the initiation complexes, TFIIE and TFIIH, are known to function at both a late stage of transcription initiation and the following promoter clearance. TFIIH has been studied extensively because of its multiple enzymatic activities, functioning not only in transcription but also in nucleotide excision repair and cell cycle control. Fewer data have been reported for TFIIE, but its potential regulatory function as to TFIIH warrants further attention. In this review, an overall perspective of the functional roles of TFIIE and TFIIH during transcription initiation and the following promoter clearance will be presented as it has emerged from recent studies.