sigma factor activity

Sigma factors act as the promoter specificity subunit of eubacterial and plant plastid multisubunit RNA polymerases, whose core subunit composition is often described as alpha(2)-beta-beta-prime. Although sigma does not bind DNA on its own, when combined with the core to form the holoenzyme, the sigma factor binds specifically to promoter elements. The sigma subunit is released once elongation begins.

• Code: GO:0016987
• Source: Gene Ontology
• Alternative labels: promoter selection factor activity plastid sigma factor activity bacterial sigma factor activity DNA-dependent RNA polymerase promoter selection factor core DNA-dependent RNA polymerase binding promoter specificity activity sigma transcription factor