RNA polymerase, alpha subunit, C-terminal (IPR011260)

Short name: RNAP_asu_C

Overlapping homologous superfamilies


Domain relationships



The core of the bacterial RNA polymerase (RNAP) consists of four subunits, two alpha, a beta and a beta', which are conserved from bacteria to mammals. The alpha subunit (RpoA) initiates RNAP assembly by dimerising to form a platform on which the beta subunits can interact. The alpha subunit consists of a N-terminal domain (NTD) and a C-terminal domain (CTD), connected by a short linker. The NTD is essential for RNAP assembly, while the CTD is necessary for transcription regulation, interacting with transcription factors and promoter upstream elements. In Escherichia coli, the catabolite activator protein (CAP or CRP) was shown to exert its effect through its interactions with the CTD, where CAP binding to CTD promotes RNAP binding to promoter DNA, thereby stimulating transcription initiation at class I CAP-dependent promoters. At class II CAP-dependent promoters, the interaction of CAP with CTD is one of multiple interactions involved in activation [PMID: 12202833].

The CTD has a compact structure of four helices and two long arms enclosing its hydrophobic core, making its folding topology distinct from most other binding proteins. The upstream promoter element-binding site is formed from helices 1 and 4 [PMID: 7491496].

GO terms

Biological Process

GO:0006351 transcription, DNA-templated

Molecular Function

GO:0003677 DNA binding
GO:0003899 DNA-directed 5'-3' RNA polymerase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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