Abstract
TATA binding protein (TBP) is a key component of the eukaryotic transcription initiation machinery. It functions in several complexes involved in core promoter recognition and assembly of the pre-initiation complex. Through gene duplication eukaryotes have expanded their repertoire of TATA binding proteins, leading to a variable composition of the transcription machinery. In vertebrates this repertoire consists of TBP, TBP-like factor (TLF, also known as TBPL1, TRF2) and TBP2 (also known as TBPL2, TRF3). All three factors are essential, with TLF and TBP2 playing important roles in development and differentiation, in particular gametogenesis and early embryonic development, whereas TBP dominates somatic cell transcription. TBP-related factors may compete for promoters when co-expressed, but also show preferential interactions with subsets of promoters. Initiation factor switching occurs on account of differential expression of these proteins in gametes, embryos and somatic cells. Paralogs of TFIIA and TAF subunits account for additional variation in the transcription initiation complex. This variation in core promoter recognition accommodates the expanded regulatory capacity and specificity required for germ cells and embryonic development in higher eukaryotes.
Highlights
Eukaryotic cells have three RNA polymerases: RNA polymerase I (RNAP-I) transcribes the ribosomal RNA genes, RNA polymerase II (RNAP-II) mostly transcribes protein-coding genes and some non-coding genes, whereas RNAP-III generally transcribes small RNA genes
For the recruitment of each RNA polymerase to the site of initiation, an additional set of polypeptides is required, the basal transcription factors. These proteins recognize the core promoter, a sequence of approximately 100 bp around the transcription start site that is required for initiation of transcription and which contains specific sequence motifs, such as the TATA box, Initiator (Inr) and Downstream Promoter Element (DPE) [1]
TFIID and other basal transcription factors have been considered a general set of proteins involved in transcription at all RNAP-II promoters
Summary
Eukaryotic cells have three RNA polymerases: RNA polymerase I (RNAP-I) transcribes the ribosomal RNA genes, RNAP-II mostly transcribes protein-coding genes and some non-coding genes, whereas RNAP-III generally transcribes small RNA genes. TATA box binding protein (TBP) and up to 14 other polypeptides called TBP-associated factors (TAFs) [2].
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