TAF1C is a component of the transcription factor SL1/TIF-IB complex, which is involved in the assembly of the PIC (preinitiation complex) during RNA polymerase I-dependent transcription [].
This entry represents subunit A (TATA-binding protein-associated factor TAFI48 or TAF1A) of RNA polymerase I. It is a component of the transcription factor SL1/TIFIB complex involved in the assembly of the pre-initiation complex (PIC). The SL1/TIFIB complex is composed of TBP (TATA-binding protein) and TAF1A (TAFI48), TAF1B (TAFI63) and TAF1C (TAFI110) []. Human ribosomal RNA synthesis by RNA polymerase I requires the activator UBF and the promoter selectivity factor SL1/TIFIB. Both TAF1B/TAFI63 and TAF1C/TAFI110 contact the promoter, whereas TAF1A/TAFI48 serves as a target for interaction with UBF and is required to form a transcriptionally active SL1/TIFIB complex responsive to UBF []. Interaction of the SL1/TIFIB subunits with TBP excluded interaction with the transcription factor IID (TFIID) subunits []. This mutually exclusive binding directs the formation of promoter- and RNA polymerase-selective TBP-TAF complexes. Therefore, TAF1A/TAFI48 may function both as a target to mediate UBF activation and as a class-specific promoter selectivity factor.
