The general transcription factors IIA, IIB, IIF, and IIE are required for RNA polymerase II transcription from the human U1 small nuclear RNA promoter

RNA polymerase II transcribes the mRNA-encoding genes and the majority of t he small nuclear RNA (snRNA) genes. The formation of a minimal functional t ranscription initiation complex on a TATA-box-contnining mRNA promoter has been well characterized and involves the ordered assembly of a number of ge neral transcription factors (GTFs), all of which have been either cloned or purified to near homogeneity: In the human RNA polymerase II snRNA promote rs, a single element, the proximal sequence element (PSE), is sufficient to direct basal levels of transcription in vitro. The PSE is recognized by th e basal transcription complex SNAP(c). SNAP(c), which is not required for t ranscription from mRNA-type RYE polymerase II promoters such as the adenovi rus type 2 major late (Ad2ML) promoter, is thought to recruit TATA binding protein (TBP) and nucleate the assembly of the snRNA transcription initiati on complex, but little is known about which GTFs other than TBP are require d. Here we show that the GTFs IIA, IIB, IIF, and IIE are required for effic ient RNA polymerase II transcription from snRNA promoters. Thus, although t he factors that recognize the core elements of RNA polymerase II mRNA and s nRNA-type promoters differ, they mediate the recruitment of many common GTF s.