<p>Transcription of yeast class III genes requires the sequential assembly of the general transcription factors TFIIIC (tau) and TFIIIB, and of RNA polymerase III, into an initiation complex composed of at least 25 polypeptides. TFIIIC, which is required for promoter recognition, transcription factor IIIB recruitment and chromatin antirepression, contains at least 5 major subunits [<cite idref="PUB00027931"/>]. In <taxon tax_id="4932">Saccharomyces cerevisiae</taxon> (Baker s yeast), gene TFC7 encodes the tau55 subunit of TFIIIC. The C-terminal half of tau55 is essential for cell viability and sufficient for TFIIIC function in DNA binding and transcription assays. The N-terminal half is non-essential and contains the phosphoglycerate mutase family domain (<db_xref db="INTERPRO" dbkey="IPR013078"/>). Partial deletions of the N-terminal domain impair tau55 function at a high temperature or in media containing glycerol or ethanol. tau55 has also been found, together with the TFIIIC subunit tau95, in a protein complex distinct from TFIIIC, which may play a role in the regulation of PolIII transcription [<cite idref="PUB00027890"/>]. A gene that may encode a closely related homologue missing most of the C-terminal domain is also found in several yeast genomes, including S. cerevisiae. These have been grouped in subfamily <db_xref db="PIRSF" dbkey="PIRSF500241"/>.</p> Transcription factor TFIIIC, tau55 subunit