RNA Polymerase III:TFIIIB:SNAPc:Type 3 Open Promoter Complex RNA Polymerase III:TFIIIB:SNAPc:Type 3 Promoter Complex RNA Polymerase III Promoter Opening at Type 3 Promoters Authored: Geiduschek, E, 2004-03-29 17:50:49 Edited: Gillespie, ME, 0000-00-00 00:00:00 Pol III initiation complexes open the promoter spontaneously. Indeed, this is the general case for DNA-dependent RNA polymerases. Only pol II, with its requirement for TFIIH-directed and ATP-dependent promoter opening is exceptional. TFIIH introduces a layer of mechanism that is not in the repertoire of any other transcriptase. Thus, it is pol III-mediated transcription that is, from a mechanistic perspective, most directly comparable with archaeal and also bacterial transcription. <p>As promoter opening has been analyzed only in the S. cerevisiae this event is Inferred from the homologous pathway in yeast. Reactome Database ID Release 43112152 Reactome, http://www.reactome.org ReactomeREACT_1485