part of has part core promoter sequence-specific DNA binding DNA-binding transcription factor activity sigma factor activity https://github.com/geneontology/go-ontology/issues/14848 https://github.com/geneontology/go-ontology/issues/15587 2010-08-11T04:12:24Z molecular_function krc GO:0000996 sigma transcription factor promoter selection factor activity GO:0001053 bacterial sigma factor activity GO:0016987 plastid sigma factor activity DNA-dependent RNA polymerase promoter selection factor core DNA-dependent RNA polymerase binding promoter specificity 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. RNA polymerase core enzyme binding transcription regulator activity regulation of DNA-templated transcription initiation