This gene encodes a transcription termination factor that is localized to the nucleolus and plays a critical role in ribosomal gene transcription. The encoded protein mediates the termination of RNA polymerase I transcription by binding to Sal box terminator elements downstream of pre-rRNA coding regions. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. This gene shares the symbol/alias 'TFF1' with another gene, NK2 homeobox 1, also known as thyroid transcription factor 1, which plays a role in the regulation of thyroid-specific gene expression. [provided by RefSeq, Apr 2011].