RNA polymerase I, subunit A (TATA-binding protein-associated factor) (IPR016629)

Short name: RNA_pol_I_TAF1A/TAFI48

Overlapping homologous superfamilies


Family relationships



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 [PMID: 7491500]. Interaction of the SL1/TIFIB subunits with TBP excluded interaction with the transcription factor IID (TFIID) subunits [PMID: 17318177]. 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.

GO terms

Biological Process

GO:0006360 transcription by RNA polymerase I

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0000120 RNA polymerase I transcription factor complex

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.