Transcription termination factor 1 (TTF1)

Transcription termination factor 1 (TTF1) is a critical nucleolar DNA-binding protein that mediates **site-specific termination of RNA polymerase I transcription** in eukaryotic cells[1][5]. TTF1 recognizes and binds to the "Sal box" terminator motifs flanking the rDNA coding region, ensuring precise cessation of rRNA synthesis and preventing collisions between transcription and replication forks[1][5]. The protein has a multi-domain structure: an N-terminal regulatory domain responsible for oligomerization and auto-inhibition, a central (trans-activation) domain involved in chromatin-specific functions and transcription termination, and a C-terminal DNA-binding domain (Myb/SANT type), homologous to the DNA-binding domains of c-Myb and yeast Reb1p[5]. Besides transcription termination, TTF1 is involved in **transcription initiation**, **chromatin looping and remodeling**, **DNA damage repair**, and **replication fork arrest**. It regulates ribosomal gene activity by promoting nucleosome repositioning, facilitating both gene activation and promoter silencing (via interactions with chromatin remodelers and noncoding RNAs)[2][5]. TTF1's function is essential for ribosomal biogenesis and genomic stability. There is no evidence for direct clinical targeting of TTF1 or its use as a biomarker in human disease outside basic research[4][5]. **Key molecular characteristics:** - Structure: Modular, three-domain protein; C-terminal Myb/SANT domain for DNA binding, central domain for transcription termination. - DNA motif recognition: Binds "Sal box" (11- to 18-bp sequence) upstream and downstream of rDNA units to facilitate precise transcription regulation[1][5]. - No direct links to common drug therapies or biomarker panels. **Notes on ambiguity:** TTF1 is also the commonly used abbreviation for "Thyroid transcription factor 1" (NKX2-1), a homeobox protein used as a lung cancer biomarker. The information here pertains strictly to "Transcription termination factor 1", **RNA polymerase I termination factor**, and not NKX2-1.

Other names

Transcription termination factor 1TTF1TTF-1TTF-IRNA polymerase I termination factorTranscription termination factor ITranscription termination factor

Not applicable, as there are no drugs reported to act via TTF1.