Transcription factor TFIIB, cyclin-like domain (IPR013150)

Short name: TFIIB_cyclin

Overlapping homologous superfamilies

Domain relationships

  • Cyclin-like (IPR013763)
    • Transcription factor TFIIB, cyclin-like domain (IPR013150)


In eukaryotes, transcription initiation of all protein encoding genes involves the polymerase II system. This sytem is modulated by both general and specific transcription factors. The general factors (which include TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIG and TFIIH) operate through common promoter elements, such as the TATA box. Transcription factor IIB (TFIIB) is of central importance in transcription of class II genes. It associates with TFIID-TFIIA bound to DNA (the DA complex) to form a ternary TFIID-IIA-IBB (DAB) complex, which is recognised by RNA polymerase II [PMID: 1876184, PMID: 1949150]. TFIIB comprises ~315-340 residues and contains an imperfect C-terminal repeat of a 75-residue domain that may contribute to the symmetry of the folded protein. The basal archaeal transcription machinery resembles that of the eukaryotic polymerase II system and includes a homologue of TFIIB [PMID: 7597027].

This entry represents a cyclin-like domain which is found repeated in the C-terminal region of a variety of eukaryotic TFIIB's and their archaeal counterparts. These domains individually form the typical cyclin fold, and in the transcription complex they straddle the C-terminal region of the TATA-binding protein - an interaction essential for the formation of the transcription initiation complex [PMID: 9177165, PMID: 10619841].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0017025 TBP-class protein binding

Cellular Component

No terms assigned in this category.

Contributing signatures

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