Factors involved in specific transcription by mammalian RNA polymerase II: purification and characterization of general transcription factor TFIIE.

Abstract
Human transcription factor TFIIE, a ubiquitous factor required for transcription initiation by RNA polymerase II, was purified to homogeneity by a combination of conventional and HPLC steps. The purified TFIIE contained equimolar amounts of 57-kDa (TFIIE-.alpha.) and 34-kDa (TFIIE-.beta.) polypeptides that were judged to be functional subunits on the basis of their copurification with transcriptional activity and the recovery of activity following renaturation of polypeptides separated by reverse-phase HPLC. TFIIE-.alpha. had an independent TFIIE activity whereas TFIIE-.beta. had no activity alone but enhanced the activity of TFIIE-.alpha.. In conjunction with gel filtration studies, which indicated a molecular mass of .apprxeq.180 kDa for the native protein, these results suggested that TFIIE is a heterotetramer containing two .alpha. and two .beta. polypeptides. Functional studies with the purified TFIIE demonstrated that it is a general initiation factor, required for all of the genes tested, but it failed to show any DNA-dependent ATPase activity.