Transcription Termination Factor, RNA polymerase I (TTF1)

Transcription termination by RNA polymerase I is largely the result of binding of a transcription termination factor to a DNA element called a transcriptional terminator. The terminator element is located downstream of the pre-rRNA coding region (RNR1) and in many species is also found immediately upstream of the gene promoters for the tandemly repeated rRNA genes. The mouse protein was partially purified and limited peptide sequence was obtained.The resulting cDNA encoded a predicted 833-amino acid protein. Recombinant mouse TTF1 specifically bound to the mouse terminator elements and stopped transcription in an in vitro system. Study of the protein identified a large C-terminal DNA-binding domain, with sequence similarity to the c-Myb oncogene, and an internal domain required for transcription termination.