Alternative titles; symbols
HGNC Approved Gene Symbol: TAF1B
Cytogenetic location: 2p25.1 Genomic coordinates (GRCh38) : 2:9,843,442-9,934,416 (from NCBI)
Eukaryotic RNA polymerases are unable to initiate RNA synthesis in the absence of additional proteins called general transcription factors, or GTFs. GTFs assemble in a complex on the DNA promoter and recruit the RNA polymerase. The multisubunit complex SL1 is required for RNA polymerase I to synthesize ribosomal RNA. SL1 consists of TATA box-binding protein (TBP; 600075), which is a universal GTF for all 3 RNA polymerases, and 3 TBP-associated factors (TAFs).
Using immunoaffinity chromatography with anti-TBP, followed by SDS-PAGE analysis, Comai et al. (1994) isolated the purified 63-kD subunit of SL1. By screening a teratocarcinoma cDNA library using degenerate PCR primers corresponding to peptide sequences of the 63-kD subunit of SL1, they obtained a nearly full-length cDNA encoding TAF1B, which they called TAFI63. Comai et al. (1994) also obtained cDNAs encoding TAF1A (604903) and TAF1C (604905). The TAF1B cDNA encodes a deduced 556-amino acid protein, which the authors suggested is missing a few amino acids at the N terminus. Western blot analysis confirmed that TAF1B is expressed as a 63-kD protein. Analysis of SL1 subunit interactions showed that all 3 TAF1 proteins bind to TBP and to each other. However, binding of the SL1 complex to TBP excluded binding of the RNA polymerase II transcription factor TFIID (see TAF2A; 313650) to TBP. Comai et al. (1994) concluded that this mutually exclusive binding directs the formation of promoter- and RNA polymerase-selective TBP-TAF complexes.
Knutson and Hahn (2011) showed that Rrn7, a subunit of the yeast Pol I core factor, and its human ortholog TAF1B are TFIIB (see 189963)-like factors. Although distantly related, Rrn7 shares many activities associated with TFIIB-like factors. Domain swaps between TFIIB-related factors showed that Rrn7 is most closely related to the Pol III general factor Brf1 (604902). Knutson and Hahn (2011) concluded that their results pointed to the conservation of initiation mechanisms among multisubunit Pols and revealed a key function of yeast core factor/human SL1 in Pol I transcription.
Naidu et al. (2011) showed that TAF1B, a subunit of human Pol I basal transcription factor SL1, is structurally related to TFIIB/TFIIB-like proteins, through predicted N-terminal zinc ribbon and cyclin-like fold domains. SL1, essential for Pol I recruitment to the ribosomal RNA gene promoter, also has an essential polymerase recruitment role, operating through TAF1B. Therefore, Naidu et al. (2011) concluded that a TAFIIB-related protein is implicated in preinitiation complex assembly and postpolymerase recruitment events in Pol I transcription, underscoring the parallels between eukaryotic Pol I, II, and III and archaeal transcription machineries.
The International Radiation Hybrid Mapping Consortium mapped the TAF1B gene to 2p (stSG39145). Di Pietro et al. (2000) mapped the TAF1B gene to chromosome 2p25 by fluorescence in situ hybridization.
Comai, L., Zomerdijk, J. C. B. M., Beckmann, H., Zhou, S., Admon, A., Tjian, R. Reconstitution of transcription factor SL1: exclusive binding of TBP by SL1 or TFIID subunits. Science 266: 1966-1972, 1994. [PubMed: 7801123] [Full Text: https://doi.org/10.1126/science.7801123]
Di Pietro, C., Rapisarda, A., Amico, V., Bonaiuto, C., Viola, A., Scalia, M., Motta, S., Amato, A., Engel, H., Messina, A., Sichel, G., Grzeschik, K.-H., Purrello, M. Genomic localization of the human genes TAF1A, TAF1B and TAF1C, encoding TAFI48, TAFI63 and TAFI110 subunits of class I general transcription initiation factor SL1. Cytogenet. Cell Genet. 89: 133-136, 2000. [PubMed: 10894955] [Full Text: https://doi.org/10.1159/000015592]
Knutson, B. A., Hahn, S. Yeast Rrn7 and human TAF1B are TFIIB-related RNA polymerase I general transcription factors. Science 333: 1637-1640, 2011. [PubMed: 21921198] [Full Text: https://doi.org/10.1126/science.1207699]
Naidu, S., Friedrich, J. K., Russell, J., Zomerdijk, J. C. B. M. TAF1B is a TFIIB-like component of the basal transcription machinery for RNA polymerase I. Science 333: 1640-1642, 2011. [PubMed: 21921199] [Full Text: https://doi.org/10.1126/science.1207656]