A universal nomenclature for subunits of the RNA polymerase III transcription initiation factor TFIIIB

Recently, a unified and systematic nomenclature for the Pol II TAFs has been adopted (Tora 2002). Researchers working on RNA polymerase III have now agreed on a universal nomenclature for the proteins that, together with the TATA-binding factor, TBP, comprise the various forms of the Pol III initiation factor TFIIIB (Table 1). In considering a universal nomenclature for the subunits of TFIIIB, it was widely agreed that the TAF3 designation (where the number denotes Pol III) was not suitable because (1) the B" component is not associated with TBP to any significant degree and (2) the TFIIB-related factor (Brf1), although associated with TBP in most, but not all systems (Hamada et al. 2001), is functionally analogous to a general transcription factor, rather than to any Pol II TAF. The universal nomenclature that has been adopted for TFIIIB subunits addresses these and other issues as follows.