Genetic characterization of general transcription factors TFIIF and TFIIB of Homo sapiens sapiens

Analysis of loci GTF2F1 and GTF2B, encoding Rap 74 (a subunit of TFIIF) and TFIIB, respectively, showed that they are present in a single copy in the human genome and are localized at 19p13.3 and 1p22, respectively. By using as probe a cDNA for Rap 30 (the other subunit of TFIIF), we localized the GTF2F2 locus to 13q14; the same probe also detected a cross-hybridizing sequence at 4q31 whose functional importance remains to be elucidated. These data and those previously published by our group demonstrate that genes coding for class II general transcription factors with reported sequence similarity to bacterial sigma proteins are scattered in different regions of the human genome, with no evidence of clustering. This dispersion and the identification of homologs of both TBP and TFIIB in Archaea suggest an early evolutionary origin of the general transcription apparatus of contemporary eukaryotes.